Biochem Flashcards
1
Q
What is indirect assay
A
Uses a labeled secondary antibody
2
Q
What is direct assay?
A
Uses a labeled primary antibody
3
Q
What is competitive assay?
A
Used when the target antigen is small and has only one epitope. Consists of labeling purified antigen instead of the antibody
4
Q
What is capture assay?
A
Analyte is bound between two antibodies, the capture antibody and the detection antibody
5
Q
Higher NAD+/NADH ratio
A
Drives catabolism because having more of the oxidized form in the cell signals an energy need
6
Q
Lower NAD+/NADH ratio
A
Drive fatty acid synthesis because having more of the reduced form in the cell can eventually provide the ATP required for synthesis
7
Q
Lower NADH/NAD+ ratio
A
Drives catabolism because having more of the oxidized form in the cell signals an energy need
8
Q
Higher FADH2/FAD ratio
A
Drive processes that result in energy storage
9
Q
What is the absolute configuration of selenocysteine?
A
S
10
Q
What is the absolute configuration of cysteine?
A
S
11
Q
What is the equivalent RNA sequence of the DNA coding for 3’-ACT-5’?
A
5’-UGA-3’
12
Q
What codon is the result of 3’-ACT-5’?
A
Stop codon
13
Q
What amino acid has two atoms in its side chain?
A
Cysteine
14
Q
How are the pyrimidines cytosine and uracil metabolized?
A
Cytosine and uracil are converted into beta-alanine and later to malonyl-CoA which is needed for fatty acid synthesis
15
Q
How is glycogen involved in aerobic respiration?
A
Glycogen can be broken down into glucose, which can directly enter glycolysis
16
Q
How are fatty acids like 3-ketoacyl-CoA involved in aerobic respiration?
A
Fatty acids like 3-ketoacyl-CoA can be broken down via beta-oxidation to produce two carbon units which are then fed into the citric acid cycle via acetyl-CoA
17
Q
How is glycogen involved in aerobic respiration?
A
Glycogen can be broken down into glucose, which can directly enter glycolysis
18
Q
What molecules are commonly used in detection or visualization of the antigen of interest in immunoassays that require labeling or conjugation with the antibodies?
A
Fluorophores, enzymes, radioisotopes, or biotin
19
Q
Transmembrane proteins generally consist of a _______ portion within the lipid bilayer and two _______ portions that face the cytosol and extracellular space
A
hydrophobic; hydrophilic
20
Q
What are the two primary determiners of protein tertiary structure?
A
Interactions between charged amino acid side chains and accumulation of hydrophobic side chains towards the inside of a globular protein, away from the charged solvent (water)
21
Q
What are the two main effects of the activation of histone deacetylase?
A
Decreased rate of transcription of the affected DNA and DNA-histone attractions will become stronger
22
Q
Insulin is a ______ hormone that promotes a _______ in blood glucose levels.
A
peptide; decrease
23
Q
Peptide hormones are ________, ________, and ________.
A
short-acting; promote second-messenger cascades; and are soluble in water.
24
Q
Steroid hormones ________, ________, and ________.
A
Bind to its receptor in the nucleus; impact transcription; share cholesterol’s fused-ring hydrocarbon structure
25
What enzyme catalyzes an irreversible step in glycolysis?
pyruvate kinase
26
What happens to a person's fuel storage after fasting for several hours and then consuming a large meal?
Liver glycogen stores increase
27
The levels of what hormone peaks just prior to ovulation?
LH
28
Chymotrypsin is an intestinal enzyme that is synthesized as a ________, which is activated by other digestive enzymes in the presence of food
zymogen
29
What helps drive lymph through the lymphatic vessels?
one-way valves that prevent fluid backflow
30
What does the endosymbiotic hypothesis state?
Mitochondria began as small, independent prokaryotic organisms that entered into a symbiotic relationship with a eukaryotic cell
31
Mitchondria have a separate set of DNA, that unlike nuclear DNA, is inherited ________.
maternally
32
Mitochondria are able to replicate in a fashion that is _________ of cell replication
independent
33
In gluconeogenesis, the reverse of step 3 of glycolysis is catalyzed by what enzyme?
fructose 1,6-bisphosphatase
34
What protein structure is intricately involved in chromosome pairing, synapsis, and recombination?
Synaptonemal complex
35
What is glycogenolysis?
The breakdown of glycogen, a polymer of glucose that is stored by the body for future energy needs
36
Glycogenolysis occurs when
one has not eaten recently or exists in a state of increased ATP demand
37
Low blood glucose levels will increase the rate of what two pathways that make glucose in the body?
Glycogenolysis and gluconeogenesis
38
What is the reason why sodium ions are able maintain a more tightly-coordinated sphere of hydration?
they have a smaller atomic radius
39
Mitosis must be arrested during what phase as a result of the replicated chromosomes being retained within the original nucleus?
prophase
40
Both leucine and isoleucine are _______ molecules
chiral
41
glycine is an ______ molecule
achiral
42
What enzyme must be present within the viral capsid of a (-) RNA virus for successful infection and replication to take place?
RNA-dependent RNA polymerase
43
What must occur for eukaryotic cells to have direct contact with viral DNA?
Viral DNA must enter the nucleus
44
What do leucine and valine have in common?
They are both neutral and nonpolar amino acids
45
________ single-stranded RNA viruses need RNA replicase to create _________ RNA strands that can be translated using host cellular machinery
negative-sense; positive-sense
46
What microbe can only replicate inside cells?
Viruses
47
How are viral proteins synthesized?
They are synthesized using host ribosomes, which are found in the rough endoplasmic reticulum
48
Viral envelopes are mainly comprised of ________ and _______ that contribute to recognition and interactions with cell receptors.
phospholipids; glycoproteins
49
Microfilaments aid what process during mitosis?
cytokinesis
50
What are two possible ways to reduce membrane fluidity?
reducing temperature and adding more saturated phospholipids
51
What organelle is involved in the catabolism of proteins?
lysosomes
52
Peroxisomes perform functions related to the ____________ and the ___________
pentose phosphate pathway; neutralization of reactive oxygen species
53
What are the two ribosomal subunits of a bacteria?
30S ribosome and 50S ribosome
54
The volume known during quiet breathing is known as what?
tidal volume
55
The volume left in the lungs after a maximal exhalation is known as what?
residual volume
56
What concept refers to the maximum amount of air we can have in our lungs?
total lung capacity
57
What is gluconeogenesis?
Generation of glucose from non-carbohydrate carbon substrates such as pyruvate, lactate, glycerol, and glucogenic amino acids like alanine and glutamine
58
What is the role of epinephrine in gluconeogenesis?
Epinephrine acts to increase the rate of substrate flux in liver cells through the gluconeogenic pathway and away from the glycolytic pathway by simulating a cAMP-regulated kinase, protein kinase A
59
What is the function of protein kinase A?
To phosphorylate and inactivate the phosphofructokinase-2 domain of the bi-functional enzyme responsible for the formation of fructose-2,6-bisphosphate
60
What enzyme is responsible for the hydrolysis of glucose-6-phosphatase to free glucose in the final step of gluconeogenesis and is required for export of glucose, via glucose transporter membrane proteins, from the renal cortex?
Glucose-6-phosphatase
61
What happens when there is an increased concentration of circulating blood glucose?
The osmotic pressure of the extracellular fluid rises, causing water to leave the cell
62
The juxtoglomerular cells in the kidney, small intestine muscle, and large intestine muscle are what kinds of muscle cells?
Smooth muscle cells
63
Membrane potential is always measured in terms of the ________ relative to the extracellular fluid
inside of the cell
64
What is the result of the change in amino acid from a glutamic acid into an aspartic acid?
Loss of a methylene group
65
Vasoconstriction _________ TPR whereas vasodilation _________ TPR
increases; decreases
66
How does the body shunt blood to working muscles to supply them with oxygen during excercise?
Through vasodilation in working muscles
67
In what blood vessel is blood pressure likely to be highest?
Aorta
68
An _______ in TPR would lead to _______ arteriole constriction restraining blood from entering the peripheral vascular system. The _______ arteriole constriction would therefore lead to a _______ cardiac output
increase; increase; increase; decrease
69
If TPR is known to _______ venous return, there would be a _______ in the amount of blood returning to the heart from the periphery via the ______ ______. This ________ in venous return would therefore lead to a _______ in ______ ______ _______.
decrease; decrease; right atrium; decrease; decrease; right atrial pressure
70
What is orthostatic hypertension?
Drop in pressure due to delayed constriction of lower body blood vessels, which is needed to maintain an adequate blood pressure when changing position from supine to standing
71
How does orthostatic hypertension cause reduced delivery of blood to the head?
Blood pools in the blood vessels of the lower extremities for a longer period, and less is returned to the heart
72
Cytochrome P450 belongs to what class of enzymes?
oxidoreductases
73
The turnover number is also known as ___________
kcat
74
What is kcat?
the time it takes one enzyme to turnover a maximum amount of substrate molecules per unit time
75
What is the equation for kcat?
kcat = Vmax / [Et]
76
If the turnover rate increases but the binding affinity (Km) remains the same, then it’s likely that the substitutions ________ entry of substrate into the active site without altering the site itself
increased
77
A heme group is classified as a ________, a ________, and a ________
cofactor; coenzyme; prosthetic group
78
What are zymogens?
inactive precursors of enzymes that require proteolytic cleavage prior to becoming active
79
What is positive cooperativity?
binding at one position or active site causes binding to take place more easily at the remaining active sites
80
A Hill coefficient greater than 1 reflects ________ _________
positive cooperativity
81
a graph of saturation versus substrate concentration for an enzyme that displays positive cooperativity would be _________
sigmoidal
82
Magnesium cations are classified as what?
cofactors
83
An uncompetitive inhibitor is an inhibitor of the _______ _______
enzyme-substrate complex
84
What enzyme is responsible for transferring a high-energy phosphate group from a donor molecule (typically ATP) to the substrate?
Kinase
85
What enzyme removes phosphate groups from their substrates?
phosphatase
86
What enzyme is responsible for binding together two smaller components?
ligase
87
What enzyme transfers functional groups from one molecule to another?
transferase
88
Many metabolic pathways, feedback loops, and cell growth and division rely on _______ _______
allosteric regulation
89
What is allosteric regulation?
a ubiquitous phenomenon in the physiology of multicellular eukaryotic organisms
90
The amino acids most likely to become phosphorylated are those which contain an ___ _____ on their side chains
OH group
91
What amino acids have an OH group on their side chains?
serine (S), threonine (T), and tyrosine (Y)
92
What is the function of SDS?
serves to disrupt the molecular forces which allow proteins to take their native conformation
93
Edman degradation _______ size of polypeptide
shrinks
94
treatment with an eluant of increasing ionic strength and pH could disrupt [statement]
the ionic bonding between polypeptide and column anions by influencing the charge state of the polypeptides, decreasing their likelihood of existing in the charged, cationic state
95
If polypeptide unfolding proceeds via a unimolecular mechanism, the rate law for the reaction must be _____ order with respect to only the polypeptide
first
96
What happens in an addition reaction?
the number of pi bonds declines, while the number of sigma bonds increases
97
Under _______ conditions, interactions between polypeptides is disrupted
reducing
98
glutamic acid is an _______ residue
acidic
99
Acidic side chains have ___ pKa values
low
100
Lysine is a ______ and [positively charged or negatively charged] residue
basic; positively charged
101
SDS applies a uniform _______ charge along the protein
negative
102
SDS is used to allow separation by ____ or _____
size; mass
103
What method uses antibody-protein affinity to retain the desired substrate on the solid-phase matrix?
immunoaffinity
104
"Salting in" refers to what?
the addition of a salt to a solution that does not yet contain very high salt concentrations
105
"Salting out" refers to what?
when salt concentrations are already high, addition of more salt decreases protein solubility
106
in cation-exchange chromatography, the stationary phase is designed to attract _______
cations
107
A protein rich in lysine (a basic amino acid) will have a [higher or lower] isoelectric point (pI) than a protein largely formed from hydrophobic residues
higher
108
A ______ pI means the protein will tend to be more ______ charged and will thus move closer to the ______ end of the gel
higher; positively; negative
109
In an electrolytic cell, the anode is _______ and the cathode is _______
positive; negative
110
in isoelectric focusing, a protein or amino acid always becomes ________ when it has reached the portion of the gel corresponding to its isoelectric point
stationary
111
What is mannitol?
a sugar alcohol that can be formed by reducing the C=O group in mannose
112
What occurs when adding bonds to oxygen?
Oxidation
113
True or False: α- and β-anomers of glucose interconvert under cellular conditions
True
114
What is Tollens’ reagent used for?
test for reducing sugars
115
Reducing sugars have free ________ groups that can be oxidized to ________ _____, with concomitant reduction of Tollens’ reagent
aldehyde; carboxylic acids
116
Tollens’ reagent contains what and is reduced to what?
an oxidized silver compound, which is reduced to elemental silver.
117
Fructose is what kind of sugar?
reducing
118
Specific rotation is an _________ value
experimental
119
Enantiomers have _____ but ________ specific rotation values
equal; opposite
120
Racemic solutions have a specific rotation of what?
0°
121
What makes L-glucose unique from D-glucose?
L-glucose does not exist in nature, and virtually no naturally-occurring enzymes are able to metabolize it unlike D-glucose
122
What happens to glucose prior to it being regulated to glycolytic or glycogenic metabolic pathways?
glucose is imported into the cell by GLUTs and trapped in the cell via hexokinase phosphorylation
123
Rate of production of G6P will [increase or decrease] with an increased accumulation of the enzyme hexokinase
increase
124
What is substrate-level phosphorylation?
the process by which a phosphate group is transferred from a phosphorylated compound to ADP or GDP, producing ATP or GTP
125
When does substrate-level phosphorylation occur?
During anaerobic glycolysis when ATP is produced from the breakdown of 1,3-BPG and PEP
126
Glycolysis involves what?
the oxidation (catabolism) of glucose to form two molecules of pyruvate, among other products
127
The investment phase refers to the first ____ steps of _________
five; glycolysis
128
_______ has been converted into two three-carbon _________ _-_________ molecules by the end of the first five steps of glycolysis
glucose; glyceraldhyde-3-phosphate
129
ATP is not produced until what phase of glycolysis?
payoff phase
130
The payoff phase refers to the last ____ steps of the overall pathway
five
131
What is the single most crucial reason for the use of anaerobic respiration?
it is capable of producing ATP at a significantly faster rate than oxidative phosphorylation
132
What does the cell do when tissue requires more ATP than aerobic respiration can produce?
turns to anaerobic methods
133
Lactic acid is a product of what?
fermentation
134
A facultative aerobe can undergo what metabolic process(es) and survive in what kind of environment?
can use oxygen as an electron acceptor in the presence of oxygen, but it can also survive in an anaerobic environment by deriving energy solely from glycolysis and subsequent fermentation
135
an _______ _________ would not be able to survive in the presence of oxygen, while an _______ _______ would require oxygen to survive
obligate anaerobe; obligate aerobe
136
Glucose 6-phosphate isomerase is involved in both __________ & ______________
glycolysis; gluconeogenesis
137
What is the function of glucose 6-phosphate isomerase?
interconverts glucose 6-phosphate and fructose 6-phosphate
138
Branch points in glycogen consist of what kinds of linkages?
α (1→6) linkages
139
α (1→6) linkages in branch points in glycogen are broken by what kind of enzyme?
glycogen debranching enzyme
140
Straight-chain glycogen is held together by what kinds of linkages?
α (1→4) linkages
141
α (1→4) linkages are broken through the action of what enzyme?
glycogen phosphorylase
142
What is the rate-limiting step of glycolysis?
phosphorylation of fructose 6-phosphate by the enzyme phosphofructokinase-1
143
Hexokinase transports ______ into the cell and is inhibited by high levels of its own product – ___.
glucose; G6P
144
when blood sugar is low, ________ is slowed, and when blood sugar is high, ________ as catalyzed by ________ occurs more rapidly
glycolysis; glycolysis; glucokinase
145
Peptidoglycan is specific to what kinds of organisms?
prokaryotes
146
What is a Gram stain?
a common biochemical technique in which a crystal violet dye is retained by a peptidoglycan (a sugar and amino acid polymer) cell wall
147
Cis-aconitate is a precursor of what molecule?
isocitrate
148
Activation of enzyme citrate synthase would cause an [increase or decrease] in the production of TCA intermediate citrate
increase
149
NADH is an inhibitor of what enzyme?
citrate synthase
150
ADP is an activator of what enzyme?
citrate synthase
151
What is the name of the enzyme that converts citrate to cis-aconitate?
aconitase
152
During gluconeogenesis, ___________ in the mitochondria is converted to ______ for export from the mitochondria
oxaloacetate; malate
153
Cytosolic malate is then re-oxidized to ___________ and converted to ___________________
oxaloacetate; phosphoenolpyruvate
154
The step in which cytosolic malate is re-oxidized to oxaloacetate and converted to phosphoenolpyruvate is the _____ ________ step in gluconeogenesis
rate-limiting
155
What is the function of Complex I?
removes 2 electrons from NADH which are then transferred to ubiquinone, or coenzyme Q. Complex I then translocates 4 protons across the inner mitochondrial membrane
156
One turn of citric acid cycle yields what?
1 GTP, 3 NADH, 1 FADH₂, and 2 CO₂
157
What is the irreversible, rate-limiting step of the citric acid cycle?
Decarboxylation of isocitrate, forming α-ketoglutarate
158
What enzyme catalyzes the decarboxylation of isocitrate, forming the five-carbon molecule α-ketoglutarate
isocitrate dehydrogenase
159
True or False: Complex II directly contributes to the gradient
False, Complex II does not directly contribute to the gradient
160
Complex IV removes how many protons from the mitochondrial matrix? How many of these protons are given to molecular oxygen along with four electrons to form water? How many of these protons are translocated across the membrane and contribute to the gradient?
8 protons; 4 protons; 4 protons
161
What is the name of the enzyme that catalyzes the rate-limiting step of glycolysis?
phosphofructokinase
162
Cytochrome c is a ___________
hemeprotein
163
Because cytochrome c contains a heme group, it also contains what metal atom?
Fe
164
Amides are [more or less] reactive than carboxylic acid derivatives
less
165
Ethoxide & NaOH are highly reactive _____ ______ & are conjugates of extremely ____ _____
strong bases; weak acids
166
Hormone-sensitive lipase is highly expressed in what two types of tissues?
adipose tissues and steroidogenic tissues
167
What is the function of hormone-sensitive lipase in adipocytes?
catalyzes the breakdown of triacylglycerols to fatty acids and glycerol through hydrolysis of ester linkages
168
Where does beta-oxidation occur?
the matrix of the mitochondrion
169
What is fatty acid oxidation?
process by which fatty acids are broken down
170
Where does fatty acid oxidation occur?
the mitochondria
171
Ketone bodies enter where after being converted to acetyl-CoA?
the TCA cycle directly
172
Prostaglandins & steroids are __________ molecules
signaling
173
Biological waxes are composed of what?
long-chain fatty acids esterified to long-chain alcohols
174
A phospholipid molecule generally consists of what?
a glycerol backbone covalently bound to two fatty acids and a phosphate group
175
The third glycerol hydroxyl group is bound to what?
a single phosphate group
176
What is required to permit phospholipids to move between the inner and outer leaflets?
enzymatic activity
177
Enzymatic promiscuity refers to what?
the case in which a single enzyme can exercise catalytic effects on a wide variety of structurally diverse substrates
178
What is the major transporter of cholesterol to the tissues of the body?
LDL
179
What transports cholesterol to the liver?
HDL
180
What two molecules primarily transport triglycerides?
Chylomicrons and VLDL
181
What is Chargraff's rule?
a rule stating that the ratio of purine nucleotides to pyrimidine nucleotides in DNA is 1-to-1
182
The following picture is a structure of what nucleobase?
adenine
183
Phosphodiester bonds connect individual _________ monomers to form _______ ____ polymers
nucleotide; nucleic acid
184
Polypeptides are composed of ______ _____ joined by _______ bonds
amino acids; peptide
185
polysaccharides are composed of _____________ monomers joined by ___________ ________
monosaccharide; glycosidic linkages
186
What is the primary function of DNA?
transmitting genetic information
187
True or False: RNA is capable of a greater diversity of functions than DNA
True
188
Compared to ribose, deoxyribose lacks an OH group on what carbon?
2'
189
What is a pentose?
a structure that has 5 carbons
190
What is a furanose?
a five-membered ring where four atoms of the ring are carbon and one is oxygen
191
What is the template for PCR?
DNA
192
What is the template for RT-PCR?
RNA
193
What are lipid rafts?
regions of the plasma membrane that are very rich in cholesterol
194
What is required for Ca²⁺ ions to be transported across the hydrophobic cell membrane?
sodium-calcium exchanger
195
What is the sodium-calcium exchanger and what form of transport does it use?
an antiporter and it uses secondary active transport
196
There is [high or low] fluidity in plasma membrane at 20℃
low
197
What is the role of cholesterol at low temperatures?
acts to prevent stacking or clustering of the fatty acyl chains in the membrane’s interior, maintaining a normal amount of fluidity
198
The lumen of the lysosome has a pH of what?
about 4.5
199
Antiporters typically utilize what form of transport as a means of transporting molecules against their concentration gradients?
active transport
200
What does the fluid mosaic model state?
transmembrane proteins are able to freely diffuse within the membrane
201
Proteins generally [do or do not] spontaneously reverse their orientation within the membrane
do not
202
Electrostatic interactions involve [charged or uncharged] amino acids
charged
203
glutamate and lysine are examples of [charged or neutral] amino acids
charged
204
alanine is an example of a [charged or neutral] amino acid
neutral
205
At high temperatures, cholesterol increases membrane ________ through attractive ___ ___ _____ interactions with neighboring lipids preventing the membrane from becoming excessively fluid
stability; van der Waals
206
At low temperatures, the steric bulk of cholesterol increases membrane ________ by preventing tight packing of phospholipid tails
fluidity
207
Potassium channels contain a _______ ______ filled with water
central cavity
208
The local polar environment of potassium channels has what effect?
reduces the energetic penalty incurred by passage through the membrane core
209
What form of transport does GLUT2 use for transport of glucose?
facilitated diffusion
210
Small, polar molecules like urea and fructose generally cross the cell membrane through what kinds of proteins?
transmembrane proteins
211
How is insulin internalized for degradation by its target cells?
through endocytosis of insulin and its receptor
212
The following picture is a structure of what amino acid?
serine
213
True or False: Serine is an amino acid that can be phosphorylated
True
214
What amino acid has a negatively charged R group and is very hydrophilic?
aspartate
215
When are peptide bonds formed?
when the carboxylic acid of one amino acid reacts with the amine group of another amino acid
216
NADPH is an example of a _____ _______ _____
strong reducing agent
217
What is 2-mercaptoethanol?
a reducing agent that is commonly used to denature proteins for SDS-PAGE analysis
218
How does 2-mercaptoethanol break disulfide bonds?
acts as an electron donor to reduce the sulfur-sulfur bond to two sulfhydryl groups disrupting quaternary structure
219
What is an apoenzyme?
an inactive enzyme that lacks a necessary cofactor
220
What are coenzymes?
small organic molecules that bind to coenzyme-dependent enzymes
221
What is Km?
the substrate concentration required to achieve Vmax/2
222
Enzymes [do or do not] affect the rate of reactions but [do or do not] affect their spontaneity
do; do not
223
What are hydrolases?
a class of enzymes that catalyze the breaking of bonds through addition of a water molecule
224
What kind of reaction is used to convert an unsaturated fatty acid into a saturated fatty acid?
hydrogenation
225
What is the isoelectric point?
the pH at which a protein or amino acid has no net charge
226
What is pepsin?
an enzyme released in stomach that catabolizes proteins to smaller peptides & amino acids
227
What is amylase?
an enzyme that catalyzes the hydrolysis of starches to sugars and is produced by the salivary glands and pancreas
228
What is hexokinase?
an enzyme that catalyzes the phosphorylation of sugars
229
What is lactase?
an enzyme that catalyzes the hydrolysis of lactose to glucose & galactose
230
Denaturation of proteins involves the disruption and destruction of what two types of protein structures?
secondary and tertiary structures
231
What is supersaturation?
a state where a solution contains more of the dissolved material than could be dissolved by the solvent under normal circumstances
232
What happens when a supersaturated system is perturbed?
the excess solute will crystallize out of solution
233
Le Chȃtelier's principle states that the abundance of a substrate will cause the [forward or reverse] reaction to be favored
forward
234
Le Chȃtelier's principle states that the abundance of a substrate will cause the [forward or reverse] reaction to be favored
forward
235
What amino acid is negatively charged and can draw away the separate hydrogen atom that is already connected to an oxygen in the OH group?
glutamic acid
236
What is the one letter code for glutamic acid?
E
237
What amino acid is very similar to threonine except that it lacks the extra methyl group that threonine has?
serine
238
True or False: CO₂ can bind hemoglobin and can dissolve to some degree in the plasma
True
239
True or False: Both kcat and the turnover number refer to the same thing
True
240
What is the formula for calculating the turnover number?
kcat=Vmax/[Et]
241
What is the turnover number defined as?
the maximum number of chemical conversions of substrate molecules per second that a single catalytic site will execute for a given enzyme concentration
242
[Et] refers to what?
the total enzyme concentration
243
Vmax refers to what?
the maximum reaction rate
244
Which carbon is the anomeric carbon for D-glucose?
C1
245
What is one key difference between the ɑ-anomer and ꞵ-anomer of D-glucose?
the ꞵ-anomer has the hydroxyl group in the equatorial position, while the ɑ-anomer has the hydroxyl group in the axial position
246
What is the one letter code for aspartic acid?
D
247
Is aspartic acid a neutral, positively charged, or negatively charged amino acid?
a negatively charged amino acid
248
What amino acid contains a methyl side chain, which is not considered a branched alkane?
alanine
249
When does the influx of Na⁺ across motor end plate occur?
Na⁺ ion channels bind the ligand acetylcholine
250
A Southern blot uses what to differentiate between mutant and wild-type alleles?
a restriction digest
251
What is required in a mutation for a Southern blot to be useful?
the mutation should either create or eliminate a restriction site, most of which are palindromes and 4 to 6 base pairs long
252
AAGCTT is a _______ sequence and is the recognition sequence for ______
palindromic; HindIII
253
Insulin promotes ___ storage because cells experiencing an insulin-mediated influx of glucose can obtain energy from that glucose
fat
254
What is driving force behind protein folding?
increased entropy made possible by the sequestration of hydrophobic residues in the protein core
255
Ribosomes in conjunction with peptidyl transferase are responsible for the synthesis of what macromolecules?
proteins
256
The reaction catalyzed by phosphofructokinase is [reversible or irreversible] under cellular conditions
irreversible
257
The reverse reaction catalyzed by phosphofructokinase during gluconeogenesis is bypassed by what enzyme?
fructose 1,6-bisphosphatase
258
What is the change in free energy of a reaction?
a thermodynamic value that depends only on the chemical identity of the reactants and products
259
True or False: Enzymes can only alter reaction kinetics, not thermodynamics
True
260
Which complex catalyzes the oxidation of NADH (formed during the TCA cycle) to NAD+ with the concomitant translocation of protons across the inner mitochondrial membrane?
Complex I
261
The movement of protons back into the matrix is coupled with what?
ATP production
262
Elevated [AMP] and low [ATP] indicate what?
inadequate ATP production
263
What is one mechanism to correct an ATP shortage?
upregulation of glycolytic activity
264
What is the principal product of glycolysis?
pyruvic acid
265
What is the function of G6P?
an allosteric inhibitor of hexokinase in order to prevent unchecked glucose phosphorylation
266
Hemoglobin has the characteristics of what type of enzyme?
allosteric enzyme
267
allosteric enzymes [do or do not] exhibit classical Michaelis-Menten kinetics
do not
268
True or False: the structure of threonine contains rings
False, the structure of threonine does not contain any rings
269
What are aromatic compounds?
compounds that contain planar, conjugated rings and follow Hückel's rule (system possesses 4n + 2 π electrons)
270
Increased expression of protease enzymes would further [increase or decrease] SREBP levels in the cell
increase
271
How does the synthesis of LDL receptors allow the cell to import cholesterol?
by binding circulating LDL and taking it in via endocytosis
272
For a water-permeable cell to lose water via osmosis, its contents must be [hypotonic, isotonic, or hypertonic] relative to its environment
hypotonic
273
What molecule cannot be directly incorporated into gluconeogenesis?
Acetyl-CoA
274
Describe the process of endocytosis
external molecules/pathogens first engulfed in a vesicle → vesicles deliver their contents to early endosomes → contents then progress to late endosomes
275
In an oxygen-poor environment, the ______ ____ _____ will slow while ___________ is activated further
citric acid cycle; glycolysis
276
Glycolysis utilizes ___, ___, & ______ to form ___ & ____
ADP; NAD⁺; glucose; ATP; NADH
277
What are the reactants and products of glycolysis?
reactants: one glucose, two NAD⁺, two H⁺, and two ATP molecules
products: two pyruvate, four ATP, and four NADH
278
How is Acetyl-CoA formed?
from the pyruvate dehydrogenase before the citric acid cycle
279
An eight-carbon fatty acid chain would require how many acetyl-CoA molecules?
four acetyl-CoA molecules
280
Each glucose molecule yields how many acetyl-CoA units?
two acetyl-CoA units
281
Which two amino acids have a carboxylic acid side chain?
aspartic and glutamic acid
282
What is melting temperature?
a measure of DNA stability
283
When fewer hydrogen bonds connecting the two DNA strands are present, the melting temperature of the DNA [increases or decreases]
decreases
284
The __ end of ssDNA often loops back onto itself due to complementary base pairing, which serves as a ______ for DNA polymerase I, providing a free __ __ _____ necessary for enzyme to initiate synthesis
3'; primer; 3' OH group
285
This picture is the structure of what amino acid?
L-alanine
286
Transamination of L-glutamate & pyruvate results in the formation of what two products?
ɑ-ketoglutarate and alanine
287
Transamination of L-glutamate & pyruvate is catalyzed by what enzyme?
alanine amino transferase
288
When does transamination occur?
when an amino group is transferred from one species to another, often to form new amino acids
289
What is one key difference between saturated and unsaturated fats?
unsaturated fats have C=C bonds whereas saturated fats have no C=C bonds
290
Why are unsaturated fats more flexible and fluid than saturated fats?
their C=C double bonds introduce a kink into the hydrocarbon tail
291
Cholesterol stabilizes membranes by making [more or less] fluid at low temperature & [more or less] fluid at high temperature
more; less
292
What is beta oxidation?
the process by which long hydrocarbons are oxidized to acetyl-CoA by enzymes in the mitochondria
293
What is the critical concentration?
the point at which no net polymerization or depolymerization occurs
294
What enzyme is responsible for catalyzing the reaction to form glyceraldehyde 3-phosphate and fructose-6-phosphate?
transketolase
295
Both glyceraldehyde-3-phosphate and fructose-6-phosphate are part of what process?
glycolysis
296
Is arginine a basic, neutral, or acidic amino acid?
basic
297
Is glutamate a basic, neutral or acidic amino acid?
acidic
298
What is produced in the final step of beta-oxidation?
acetyl-CoA
299
How can the number of acetyl-CoA molecules produced from a complete reaction of a fatty acid be determined?
divide the number of carbons by 2
300
Denaturation via SDS & mercaptoethanol effectively removes all forces that hold together what kinds of protein structures?
secondary, tertiary, & quaternary structures
301
Only [L or D] amino acids are produced in cells and used to form protein
L amino acids
302
The tertiary structure of a protein is driven by what?
the tendency of hydrophobic residues to bury themselves inside the molecule, away from water, as well as interactions between side chains
303
Extended cardiac arrest leads to a decrease in what in the cells of vital organs?
ATP concentration
304
It is extremely [easy or difficult] for an organism to alter the temperature of a specific subcellular component
difficult
305
Gluconeogenesis and the pentose phosphate pathway both share the molecule, ______________, a glycolytic intermediate
glucose-6-phosphate
306
The pentose phosphate pathway begins with the production of __________________, which can be fed into the ______ _____ _____ and the _______ ______ _____
glyceraldehyde-3-phosphate; citric acid cycle; electron transport chain
307
____________ is important in the production of nucleic acids
ribose-5-phosphate
308
The formation of a polypeptide takes place via what kind of reaction?
dehydration reaction
309
Pinocytosis is a specific form of what?
endocytosis
310
Endocytosis requires large amounts of ___ and is classified as ______ ________
ATP; active transport
311
To proceed, gluconeogenesis must overcome the _____ ____________ _____ that occur during glycolysis
three irreversible steps
312
Step 10 of gluconeogenesis indicates the conversion of ________________ to ________
phosphoenolpyruvate; pyruvate
313
The reverse of the conversion of phosphoenolpyruvate to pyruvate requires catalysis by what two enzymes?
PEP carboxykinase; pyruvate carboxylase
314
_________ must undergo further modification before entering into glycolysis, D-_______ can enter into that series of reactions right away
galactose; glucose
315
In the electron transport chain, what is reduced to form water?
O₂
316
Protein is generally [more or less] dense than cholesterol?
more
317
Protein is generally [more or less] dense than cholesterol
more
318
HDL molecules would have relatively more ______ than LDL molecules
protein
319
What is the one letter code of asparagine?
N
320
The residue of asparagine contains an extra nitrogen atom in the form of an _____ functionality
amide
321
Amides are overall [acidic, neutral, or basic]
neutral
322
What happens when a G protein-coupled receptor (GPCR) binds a ligand?
Associated protein's ɑ subunit exchanges a bound GDP molecule for GTP, thus transitioning to an active conformation
323
Sucrose disaccharide is made up of what monomers?
one D-glucose and one D-fructose unit
324
Yes or No: Will both D-glucose and D-fructose be able to enter into the glycolytic cycle once they are phosphorylated?
Yes
325
The rate of the reaction is dependent on what two factors?
concentration of the reactants and the rate constant
326
As the pyruvate dehydrogenase complex is created and bound with substrate, the amount of unbound enzyme and substrate [increases or decreases]
decreases
327
The pushing of protons from the mitochondrial matrix into the intermembrane space can only be seen during what?
the establishment of the proton gradient
328
During regeneration of ATP, H⁺ ions will instead flow from the _____________ _____ back to the _____________ _____ through ATP synthase
intermembrane space; mitochondrial matrix
329
This picture is a structure of what amino acid?
proline
330
This picture is a structure of what amino acid?
tryptophan
331
How can proline be identified?
the amino terminal that is directly attached to its side chain in the form of a heterocyclic ring causing proline to promote "kinks"
332
NAD is an example of a what?
a coenzyme
333
What are coenzymes?
a subset of cofactors that tend to bind loosely to their associated enzymes
334
Coenzymes are known for what?
transferring functional groups between species
335
NAD donates its hydrogen to what complex in the ETC?
Complex I
336
What is the primary function of the pentose phosphate pathway?
To produce NADPH
337
What is the first molecule that is involved in the pentose phosphate pathway?
glucose-6-phosphate
338
The formation of a disulfide bond involves ________, so it can be coupled with a ________ reaction
oxidation; reduction
339
What is the name of the molecule depicted?
acetaldehyde
340
What is the oxidized form of ethanol called?
acetaldehyde
341
All amino acids have a ______ and an ______ group, corresponding to pKa values of about _ and _-___, respectively
carboxyl; amino; 2; 9-10.5
342
What is the function of carnitine?
to transport fatty acids into the mitochondria
343
Fatty acids are utilized to create what for the citric acid cycle?
acetyl-CoA
344
Fatty acids are utilized to create what for the citric acid cycle?
acetyl-CoA
345
The Na⁺/K⁺ pump brings _ potassium ions into the cell for every _ sodium ions it expels
2; 3
346
The act of coupling [would or would not] change the activation energy of a process
would not
347
What is the goal of reaction coupling?
to make the total of the two reactions exergonic in nature
348
Which three complexes in the ETC pump protons from the mitochondrial matrix into the intermembrane space?
Complexes I, III, and IV
349
What is SDS?
a denaturant and a charged molecule with a long hydrophobic tail
350
What is the purpose of SDS having a charged molecule with a long hydrophobic tail?
to coat proteins with a uniform charge density
351
What is the purpose of SDS being a denaturant?
to prevent proteins from running through the gel according to their cross-sectional profiles rather than their masses
352
A typical enzyme-catalyzed reaction at low substrate concentration is _____ order with regard to substrate. However, as [S] increases and the reaction velocity reaches Vmax, it undergoes a shift to become ____ order
first; zeroth
353
The plasma membrane is a lipid bilayer made of phospholipids w/ _____ "heads" & ________ "tails"
polar; nonpolar
354
Nitrogen gas is extremely [reactive or unreactive]
unreactive
355
Insulin allows a patient to take in ______ and produce ___ through glycolysis, while also stimulating the citric acid cycle and the electron transport chain
glucose; ATP
356
Pyruvate is a product of what process?
glycolysis
357
Increased levels of ATP correlates with a [rise or drop] in AMP concentration
drop
358
Regulation of _____ ____ ___________ occurs once nutrients have been taken up into the bloodstream and cells
fatty acid digestion
359
Enzyme evidently binds its substrate more effectively when ATP levels are [high or low]
low
360
acetyl-CoA is a product that is exclusive to _______ __________
aerobic respiration
361
___ is a product of both anaerobic & aerobic respiration through glycolysis
CO₂
362
Aerobically, _ pyruvates & _ molecules of CO₂ will be generated
2; 2
363
Anaerobically, in yeast fermentation, _ molecules of ethanol & _ molecules of CO₂ will be generated
2; 2
364
In anaerobic lactic acid fermentation, no ___ is produced
CO₂
365
Complex IV adds ___ protons to the intermembrane space per oxygen-reducing reaction
two
366
Complex III pumps ____ protons
four
367
A typical rate vs. pH curve is _________ in shape
parabolic
368
What macromolecules are typically inserted in cytosolic leaflet of ER after synthesis?
lipids
369
What is the name of the proteins positioned between the two leaflets that move lipids into the inner leaflet?
flippases
370
What organelle is continuous with the ER?
nuclear membrane
371
__________ occurs in all cells, while ______________ only occurs in the liver and cortex of the kidney
glycolysis; gluconeogenesis
372
Cysteine is a _____ amino acid with the ability to participate in __________ _______
polar; disulfide bridges
373
Glycine is a ________, _______ residue that lacks ______
nonpolar; neutral; sulfur
374
Glycine is a ________, _______ residue that lacks ______
nonpolar; neutral; sulfur
375
The rigidity of the proline ring disrupts the formation of what?
alpha helices and beta sheets
376
For lysine to bind to Na⁺ and not to Cl⁻, it must contain only __________ charged groups and no __________ ones
negatively; positive
377
The electron transport chain is present on the _____ ____________ _______ and pumps protons from the ______ into the ____________ _______
inner mitochondrial membrane; matrix; intermembrane space
378
What is DNP?
an uncoupling agent which allows proteins to leak back across the inner mitochondrial membrane, therefore destroying the gradient
379
Le Chȃtelier's principle states that, with a decrease in product concentration, the system will shift [left or right] to reestablish equilibrium
right
380
Reaction quotient Q is calculated as what?
[products]/[reactants]
381
Q＜Keq corresponds to an [increase or decrease] in ΔG
decrease
382
Q＜Keq corresponds to an [increase or decrease] in ΔG
decrease
383
During gluconeogenesis, the conversion of glucose to glucose-6-phosphate is bypassed by what enzyme?
glucose-6-phosphatase
384
During gluconeogenesis, the conversion of glucose to glucose-6-phosphate is bypassed by what enzyme?
glucose-6-phosphatase
385
By reducing the activation energy, the rates of the forward & reverse reaction [increase or decrease]
increase
386
Secondary hyperparathyroidism can be caused by what three factors?
elevated blood phosphate levels, chronic kidney disease, and decreased dietary calcium intake
387
Extracellular calcium is required for what?
neurotransmitter release
388
Extracellular calcium is involved in the mechanism of what?
contraction of the cells of all muscle types
389
PTH levels [increase or decrease] in response to low blood calcium concentrations
increase
390
What are the thyroid hormone (T₃) and its prohormone (T₄)?
modified amino-acid hormones that behave much like steroid hormones in their global regulation of metabolism
391
ACTH is a [peptide or steroid] hormone
peptide
392
Peptidoglycan is formed from amino acids and sugar and is thus [hydrophilic or hydrophobic]
hydrophilic
393
Methyl violet 10B is [hydrophilic or hydrophobic] because it is charged
hydrophilic
394
Destruction of reactive oxygen species is a form of __________ __________
antioxidant protection
395
What is one function of osteoclasts?
bone resorption
396
What is bone resorption?
the destruction of bone to release its component minerals and ions into the blood
397
Downstream means _______ ____ the body
farther down
398
The three parts of the small intestine are ordered _______ → _______ → _____
duodenum → jejunum → ileum
399
The three parts of the large intestine are ordered _____→ _______ → _____
cecum → colon → rectum
400
Glutamate decarboxylase is an enzyme that catalyzes the removal of a __________ _____ from glutamate
carboxylate group
401
This picture is a structure of what molecule?
glutamate
402
This picture is a structure of what molecule?
GABA
403
Totipotent stem cells are typically found in ________ tissue
zygotic
404
Pluripotent stem cells are typically found in ___________ tissue
embryonic
405
MSCs are _____ stem cells
adult
406
Adult stem cells give rise to one of several cell types and are thus ___________
multipotent
407
What is a negative control group?
a control that does not provide a treatment response
408
What is a negative control group?
a control that does not provide a treatment response
409
G1 phase is characterized by what?
cell growth
410
By passing the G1/S checkpoint the cell commits to _______, check that it is [large or small] enough, and that ___ is not damaged
dividing; large; DNA
411
This picture is the structure of what amino acid?
threonine
412
____ is oxidized by Complex I while ____ is oxidized later by Complex II
NADH; FADH₂
413
If a mutation rendered NAD+ coenzyme nonfunctional, if a mutation rendered NAD+ coenzyme nonfunctional, ____ still provides e- needed to facilitate oxidative phosphorylation; just that the process slows down
FADH₂
414
Changing amount of enzyme affects what?
how fast the reaction can occur
415
What is a mixed inhibitor?
one that has effects that are a mix of both competitive and noncompetitive effects affecting both Vmax & Km
416
Antibodies of different isotypes differ in their [constant or variable] region
constant
417
Antibodies of different isotypes differ in their [constant or variable] region
constant
418
Cells will [swell or shrink] as water flows down its concentration gradient from low to high solute
swell
419
Each unique order of amino acids represents a distinct __________
tripeptide
420
What are disulfide linkages?
those that form between two free -SH groups, yielding S-S bonds
421
What can be used to break disulfide linkages?
a reducing agent
422
What can be used to break disulfide linkages?
a reducing agent
423
Disulfide linkages form between two ________ residues
cysteine
424
Which complex does not contribute to the proton gradient and instead oxidizes FADH₂ and reduces ubiquinone?
Complex II
425
What two amino acids contain aromatic rings?
tyrosine and phenylalanine
426
What two amino acids contain aromatic rings?
tyrosine and phenylalanine
427
What is the one letter code for tryptophan?
W
428
What is the one letter code for tyrosine?
Y
429
What is the one letter code for phenylalanine?
F
430
What enzyme mediates the first step in glycolysis?
hexokinase
431
What enzyme mediates the first step in glycolysis?
hexokinase
432
What enzyme mediates the first step in glycolysis?
hexokinase
433
How does hexokinase mediate the first step in glycolysis?
adds a phosphate group to the sixth carbon to trap glucose within the cell
434
What is glucokinase?
an isoenzyme of hexokinase that is used in liver and pancreatic beta cells
435
Acetyl-CoA is fed into the Krebs cycle to produce what?
three NADH, one FADH₂, and one GTP molecule
436
Acetyl-CoA is fed into the Krebs cycle to produce what?
three NADH, one FADH₂, and one GTP molecule
437
One NADH is used to produce how many ATP molecules?
3
438
One FADH₂ is used to produce how many ATP molecules?
2
439
How many molecules of ATP are produced in total from one molecule of acetyl-CoA?
12
440
How many molecules of ATP are produced in total from one molecule of acetyl-CoA?
12
441
What is the Michaelis-Menten equation?
442
What is the Michaelis-Menten equation?
443
NADH is _______ during the ETC
oxidized
444
As the final electron acceptor in the ETC, oxygen is reduced to form what?
water
445
What four enzymes used for gluconeogenesis to overcome the three irreversible steps that occur during glycolysis?
glucose-6-phosphatase, fructose 1-6-bisphosphatase, PEP carboxykinase, and pyruvate carboxylase
446
AMP is a main effector of what enzyme?
phosphofructokinase
447
AMP is a main effector of what enzyme?
phosphofructokinase
448
Type II diabetes is marked by what?
an acquired resistance to insulin
449
Cells not responding to insulin despite high blood sugar levels and unimpeded insulin production results in the systemic appearance of _____________
hyperglycemia
450
What is the primary function of the pentose phosphate pathway?
to produce NADPH and five-carbon sugars, or pentoses
451
What is NADPH used for?
fatty acid synthesis
452
Fatty acid formation from carbohydrates occurs predominantly in where?
the liver
453
An increase in glucose concentration generally results from [high or low] blood sugar levels
low
454
An increase in glucose concentration generally results from [high or low] blood sugar levels
low
455
True or False: It is possible for a reaction to be spontaneous yet also proceed slowly
True
456
Catalysts change the activation energy necessary to accomplish the reaction by altering the _________
mechanism
457
Multiple proteins of distinct molecular weights were present in sample would result in what?
multiple well-defined bands
458
What is the result of partial degradation breaking the protein?
a very large number of lighter-colored bands forming
459
What are the three enzymes that catalyze the three irreversible steps of glycolysis?
hexokinase, phosphofructokinase, and pyruvate kinase
460
Branching of glycogen [increases or decreases] its solubility
increases
461
Why does the branching of glycogen increase its solubility?
it arranges its many OH groups in such a way that surrounding water molecules can easily dehydrate them
462
Enzymes used in glycogen degradation can only work on the ___-________ ends of glucose
non-reducing
463
What is the one letter code for phenylalanine?
F
464
What is the one letter code for phenylalanine?
F
465
Phenylalanine is a [polar or nonpolar] amino acid
nonpolar
466
___________ requires anaerobic conditions to become active
fermentation
467
What two processes can proceed in the presence and absence of oxygen?
glycolysis and gluconeogenesis
468
Regulation of blood pH involves what?
the interconversion between water and carbon dioxide, carbonic acid, and bicarbonate
469
Oleic acid has __ carbons, a single _____ double bond, and the double bond is on its __ carbon from the non-COOH end
18; trans; 9th
470
Oleic acid has __ carbons, a single _____ double bond, and the double bond is on its __ carbon from the non-COOH end
18; trans; 9th
471
Linoleic acid has _ carbons and _ double bonds
18; 2
472
A dynein "walks" down its microtubule towards the [plus or minus] end
minus
473
What is retrograde transport?
the act of traveling inward from the cell membrane
474
Charged residues [increase or decrease] solubility
increase
475
As nonpolar molecules, steroids generally pass directly through the ______ ________ and bind _______ ___________ ________
plasma membrane; soluble cytoplasmic receptors
476
If the enzyme stabilized the substrate, this would [increase or decrease] the driving force of the reaction and [increase or decrease] the ΔG.
decrease; increase
477
Enzymes [do or do not] have high affinity for products
do not
478
As covalent bonds, peptides [do or do not] easily break
do not
479
True or False: Allosteric activators will increase the initial rate of the reaction
True, allosteric activators will increase the initial rate of the reaction
480
True or False: Allosteric activators will increase the Vmax
False, allosteric activators will not increase the Vmax
481
Hydrolysis of ATP is an [exergonic or endergonic] reaction that generates energy to power [favorable or unfavorable] processes.
exergonic; unfavorable
482
By coupling the hydrolysis of ATP to another reaction, the net sum of the energies of the two reactions will be [exergonic or endergonic] overall
exergonic
483
What is FISH (fluorescence in situ hybridization) used for?
detection of DNA sequences
484
FISH (fluorescence in situ hybridization) specifically involves
probes that bind to complementary regions of the chromosome
485
Gluconeogenesis occurs in what two organs?
liver and kidneys
486
A ΔG° of 0 corresponds to a Keq of _
1
487
A ΔG° of 0 corresponds to a Keq of _
1
488
What is the function of nucleoside-diphosphate kinase?
takes a phosphate group from ATP and places it on a GDP molecule to make GTP
489
Every enzyme has a specific ___________ and __ at which it functions most effectively
temperature; pH
490
The following picture is a structure of what molecule?
deoxyadenosine triphosphate
491
Deoxyadenosine triphosphate is a __________
nucleotide
492
How are compounds separated in ion-exchange chromatography?
net charge
493
What is the net reaction for the Krebs cycle with the correct stoichiometric ratios?
Acetyl-CoA + 3 NAD⁺ + FAD⁺ + GDP + Pᵢ + 2H₂O ! 2CO₂ + 3 NADH + FADH₂ + GTP + 2H⁺ + CoA
494
Xylulose 5-phosphate is an ____________ in the pentose phosphate pathway and is produced during the ______ step of the non-oxidative
intermediate; second
495
Both myoglobin and hemoglobin contain ____, which allows them to carry oxygen
heme
496
What is the name of the catecholamine that relies on vesicular transport, the breakdown of which causes conditions like Parkinson's disease?
dopamine
497
Vitamin C and the B complex vitamins are the two groups of vitamin that are [water or fat]-soluble
water
498
Vitamin C, also known as ascorbic acid, can function as an ___________ and as a ________
antioxidant; cofactor
499
The many different vitamin B members can function either as __________ ______ or as ________
prosthetic groups; coenzymes
500
Treadmilling can occur when the polymer is able to grow at the [+ or -] but shrinks at the [+ or -] end
+; -
501
What is the one letter code for proline?
P
502
What is the one letter code for phenylalanine?
F
503
The reaction quotient (Q) is measured as what?
the relative concentrations of the products divided by that of the reactants
504
In size-exclusion chromatography, the beads in the column are permeated by _____ _____
small pores
505
In size-exclusion chromatography, [larger or smaller] proteins tend to elute relatively quickly
larger
506
In size-exclusion chromatography, [larger or smaller] proteins tend to elute relatively quickly
larger
507
For every molecule of glucose, ___ three-carbon G3P intermediates may be produced, which then result in ___ pyruvate molecules as products
two; two
508
Hemoglobin is what type of enzyme?
allosteric enzyme
509
Hemoglobin will exhibit what type of curve?
sigmoidal kinetic curve
510
This hyperbolic curve is a characteristic of what type of kinetics?
Michaelis-Menten kinetics
511
True or False: FAD has a role in glycolysis
False, FAD has no role in glycolysis
512
What is the net reaction for glycolysis?
glucose + 2 NAD⁺ + 2 ADP --> 2 pyruvate + 2 NADH + 2 ATP
513
1 glucose molecule yields how many ethanol and CO₂ molecules?
2 ethanol and 2 CO₂ molecules
514
What are the two amino acids that contain sulfur?
methionine and cysteine
515
Tryptophan is a [acidic, neutral, or basic] amino acid that has a [positively or negatively] charged carboxyl group and a [positively or negatively] charged amino group
neutral; negatively; positively
516
At pH 1, the amino group (pKa~9.2) on tyrosine is [protonated or deprotonated] and [positively or negatively] charged.
protonated; positively
517
At pH 1, the carboxylic acid group (pKa ~ 2.2) is also [protonated or deprotonated], making it neutral & the overall charge of tyrosine _
protonated; +1
518
Hexokinase is the first enzyme to catalyze a step of __________, which occurs in the _________
glycolysis; cytoplasm
519
What is arachidonic acid?
a lipid without a phosphate moiety
520
What are the two ways competitive inhibitors block the substrate from binding at the enzyme's active site?
stimulating the substrate itself or by stimulating the transition state
521
Enzymes have a particularly strong affinity for the ___________ ______ of their associated reaction
transition states
522
What is the role of cholesterol in the membrane?
to provide fluidity within the otherwise rigid phospholipid structure
523
Succinate dehydrogenase utilizes ___ as its oxidizing agent
FAD
524
Nicotinic receptor is highly specific for what neurotransmitter?
acetylcholine
525
Histidine has an _________ ____
imidazole ring
526
Arginine contains a ________ group
guanidine
527
Azide groups are composed of what?
three consecutive nitrogen atoms
528
kcat is used to describe what?
the rate-limiting step of catalysis under saturating conditions of substrate
529
Traditional Michaelis–Menten kinetics describes a ___________ dependence of V₀ on substrate concentration
hyperbolic
530
________ ________ bind to anion-exchange columns
anionic peptides
531
The strength of the binding to anion-exchange columns depends on the overall ______ of the peptide
charge
532
Stimulation of vascular smooth muscle will result in [vasodilation or vasoconstriction]
vasoconstriction
533
Aspirin can inhibit the [dilation or constriction] of blood vessels
constriction
534
True or False: Glycolysis requires the proper functioning of ATP synthase
False, glycolysis does not require the proper functioning of ATP synthase
535
Transferase will take a segment of the branched chain that is one unit away from the branch site and relocate it to the parent chain, creating a new ________________
ɑ-1,4 linkage
536
In an ɑ-helix, the amino acid residues are directed [inward or outward], [toward or away from] the long axis of the helix.
outward; away from
537
A molecule being hydrophilic permits the formation of what between neighboring residues?
salt bridges
538
_________ ______ are tightly bound to their parent compounds
prosthetic groups
539
Fe is able to shift while binding oxygen describing a phenomenon known as what?
cooperative binding
540
Iron is part of the heme group, which is a ________ of hemoglobin
cofactor
541
__________________ is the product of Step 1
glucose-6-phosphate
542
True or False: AMP does allosterically activate step 3 of glycolysis and inhibits the final step
False, AMP does allosterically activate step 3 of glycolysis but does not inhibit the final step
543
What types of proteins bind hormones and other ligands to activate signal transduction pathways?
transmembrane proteins
544
Activation of signal transduction pathways results in a change in what?
gene expression
545
Such proteins may form channels that allow [charged or uncharged] molecules to pass
charged
546
ATP synthase spans inner mitochondrial membrane and is thus a _____________ _______
transmembrane protein
547
Glycolysis is a [anabolic or catabolic] process with a [positive or negative] net change in free energy.
catabolic; negative
548
Reversible glycolytic steps refer to what?
those reactions that do not serve as committed steps because they do not represent a large free energy
549
An increase in CO₂ yields a(n) [increased or decreased] plasma pH through the action of the blood buffer system
decreased
550
Allosteric regulation is achieved through what?
the binding of a molecule at a site other than the active site
551
Catalysis of a reaction is the main function of an _____ and occurs at the ______ ____
enzyme; active site
552
The formula, C₅H₁₁O₂, is the chemical formula of what amino acid?
methionine
553
Methionine is a residue that contains a _________ functionality as part of its side chain and so [does or does not] possess a free -SH group
thioester; does not
554
Glucose-6-phosphate and fructose-6-phosphate are _______
isomers
555
During synthesis of malate, fumarate experiences the addition of water across its double bond resulting in what?
the replacement of this bond with an OH group on one carbon and a hydrogen atom on the other
556
The replacement of a C=C bond with an OH group on one carbon and a hydrogen atom on the other is an example of what?
classic hydration reaction
557
What three molecules are the regulators of the final step of glycolysis?
ATP, acetyl-CoA, and fructose-1,6-bisphosphate
558
____________ is regenerated after every Krebs cycle
oxaloacetate
559
Two high-energy molecules like nucleotide triphosphates will release a molecule of _____________ & that this species will likely be hydrolyzed into _________ ________
pyrophosphate; inorganic phosphate
560
Stearic acid has __ carbons and _ carbon-carbon double bonds
18; 0
561
________ is formed in the citric acid cycle because it is formed downstream of the step catalyzed by phosphofructokinase
citrate
562
Glucose-6-phosphate is [upstream or downstream] of the third step
upstream
563
____ _____ is transferred from acetyl-CoA to the enzyme _________ _______________ , which then carries that group across the membrane via a transmembrane protein
acyl group; carnitine acyltransferase
564
How are polypeptides formed?
dehydration synthesis reactions that link amino acids with peptide bonds
565
Glutamate, the conjugate base of glutamic acid, has a _____ functionality as part of its side chain & as such, it possesses an added _________ _________in comparison to other species
-COO-; resonance structure
566
What are "kinases?"
enzymes that can phosphorylate or dephosphorylate molecules
567
Pyruvate kinase is responsible for what?
converting PEP into pyruvate
568
What is a glycopeptide?
a peptide with an attached carbohydrate moiety
569
What is a sphingolipid?
a specific category of lipid molecule that contains a sphingoid backbone
570
Phosphorylation can denature some ________, while others require phosphorylation to ________ __ ___
proteins; function at all
571
Most enzymes are sensitive to ______ and the addition of P groups can denature or renature them through alteration of the ______ ___________ of the enzyme
charge; charge distribution
572
Lactate can be reincorporated into a glucose molecule through _____________
gluconeogenesis
573
Entropic penalties are incurred when amino acids are exposed to an environment in which they are [poorly or richly] soluble
poorly
574
Leucine, valine, and phenylalanine are all ___________ amino acids
hydrophobic
575
What are the three products of the TCA cycle?
ATP, citrate, and NADH
576
What is the name of the enzyme used in gluconeogenesis that converts pyruvate to oxaloacetate?
pyruvate carboxylase
577
What is the name of the enzyme used for conversion of pyruvate to acetyl-CoA and is therefore inhibited in times of high acetyl-CoA?
pyruvate dehydrogenase
578
Isoelectric focusing separates proteins based on their isoelectric point (the pH at which the net charge of the protein is zero) and ion exchange chromatography separates proteins based on their what?
net charge
579
SDS-PAGE separates proteins based on their
mass
580
Affinity chromatography separates proteins based on
their interactions with specific ligands
581
During conversion of α-ketoglutarate to oxaloacetate in the citric acid cycle, how many molecules of NADH and FADH2 are generated?
2 molecules of NADH and one molecule of FADH2 are generated
582
What enzyme catalyzes the final step of both gluconeogenesis and glycogenolysis?
glucose 6-phosphatase
583
The efficiency of an enzyme is measured by what?
kcat/kₘ ratio
584
Which amino acid has the one letter code D?
aspartate
585
What amino acid can form an ion pair with aspartate?
arginine
586
What is the one letter code for aspartate?
D
587
What three enzymes are used during cDNA cloning?
DNA polymerase, DNA ligase, and reverse transcriptase
588
When tryptophan is replaced with leucine, what is the reason for the stability of the PRR–prorenin complex decreasing?
it is due to the elimination of a π-stacking interaction with the side chain of tryptophan
589
Galactose is a C-4 epimer of glucose, which means that it is a what?
six-carbon aldose
590
What is Kₘ?
the substrate concentration necessary to reach 1/2 Vmax
591
Adenine contains _ donor and _ acceptor
1; 1
592
Thymine contains _ donor and _ acceptor
1; 1
593
Guanine contains _ donors and _ acceptor
2; 1
594
Cytosine contains _ donor and _ acceptors
1; 2
595
How can the lysine side chain form isopeptide bonds (Hint: same way that peptide bonds are formed)?
by reacting with a carboxylic acid group
596
Maltose contains an __________ bond, which means that the carbons involved are the C1 and C4 of the respective monosaccharides
ɑ-1,4 glycosidic
597
C1 is the anomeric carbon and a disaccharide that has a C1 carbon that is not involved in a glycosidic bond is said to have a __________ end, which is the requirement of a ________ _____
hemiacetal; reducing sugar
598
At low pH, the [protonation or deprotonation] of functional groups is the most likely cause of decreased activity and at high pH, [protonation or deprotonation] of functional groups is the most likely cause of decreased activity
protonation; deprotonation
599
This is the structure of what amino acid?
histidine
600
This is the structure of what amino acid?
lysine
601
Fasting leads to ________ _________ and _______________, then continued fasting leads to the production of ketone bodies by sustained fatty acid oxidation
glycogen breakdown; gluconeogenesis; sustained fatty acid oxidation
602
Phosphoglucose isomerase is an enzyme that is involved in what process?
glycolysis
603
Succinate dehydrogenase is also known as what in the electron transport chain?
Complex II
604
Overexpression of succinyl-CoA synthetase results in what?
increased production of succinate
605
What is the name of the enzyme that catalyzes the rate-limiting step in glycogen breakdown (glycogenolysis)?
glycogen phosphorylase
606
The glucose polymer in liver (glycogen) is formed by glycosidic bonds between glucose molecules through ___________ linearly and _________ linkage at branch point
ɑ-1,4 linkage; ɑ-1,6 linkage
607
What three compounds are gluconeogenic precursors?
lactate, oxaloacetate and glycerol
608
Phosphogluconate is involved in what pathway?
pentose phosphate pathway
609
Increased activity of succinyl–CoA synthetase will result in greater levels of what two reaction products?
succinate and GTP
610
Succinyl–CoA is the substrate of the reaction and its levels will likely [increase or decrease] with increased succinyl–CoA function
decrease
611
What is lipoic acid?
a cofactor for the enzyme pyruvate dehydrogenase
612
What is the function of the enzyme pyruvate dehydrogenase?
catalyzes the conversion of pyruvate to acetyl-CoA
613
The electron transport chain uses the free energy from redox reactions to pump protons from ____________ ______ to the_____________ _____ thereby generating an electrochemical gradient across the inner mitochondrial membrane
mitochondrial matrix; the intermembrane space
614
What is the intermediate compound between succinate and malate in the citric acid cycle?
fumarate
615
What enzyme catalyzes the conversion of glucose 6-phosphate to 6-phosphogluconolactone in the pentose phosphate pathway?
glucose 6-phosphate dehydrogenase
616
The side chain of tyrosine contains what?
a phenol
617
The side chain of threonine contains what?
a secondary alcohol with a stereogenic center
618
The side chain of lysine contains what?
a four carbon chain with an ε-amino group
619
The side chain of tryptophan contains what?
a CH2 attached to an indole ring
620
Only [L isomers or D isomers] of amino acids are used for protein synthesis
L isomers
621
What are three properties of glutamine (Gln)?
glutamine (Gln) possesses two nitrogen atoms in its formula, is zwitterionic at pH 7, and is neutral because its side chain is neither acidic nor basic at pH 7
622
Arginine (Arg) possesses how many nitrogen atoms in its formula?
four nitrogen atoms
623
Arginine contains a [positively or negatively] charged amino acid side chain
positively
624
What do tyrosine, serine, and threonine have in common?
they can all be phosphorylated
625
What amino acid cannot be phosphorylated?
alanine
626
Histidine is a _____ amino acid and can be [positively or negatively] charged
basic; positively
627
What is the Michaelis-Menten equation?
V₀ = (Vmax [S])/(Km + [S])
628
What does the Michaelis-Menten equation describe?
the velocity (v₀) of any enzyme-catalyzed reaction as a function of substrate concentration [S]
629
In gel electrophoresis, [large or small] molecules migrate more slowly
large
630
What dNMP is the largest dNMP?
purine deoxyguanosine monophosphate (dGMP)
631
Energy input from the hydrolysis of ATP is only required for what type of transport?
active transport
632
In active transport, in which ions travel [down or against] their concentration gradient
against
633
What is phosphorylation?
a common post-translational modification that is facilitated by protein kinase enzymes
634
Phosphorylation can occur at residues that contain a _______ _____ on their side chains
hydroxyl group
635
What are the names of the three amino acids that contain a hydroxyl group on their side chains?
serine, threonine, & tyrosine
636
How do proteases degrade proteins?
by hydrolyzing the peptide bonds that link amino acids in the polypeptide chain
637
[Smaller or Larger] proteins or protein fragments travel through the gel matrix toward the positive anode faster than larger proteins
Smaller
638
Glucagon [increases or decreases] the rate of glycolysis and [increases or decreases] the rate of gluconeogenesis
decreases; increases
639
Leptin resistance refers to what?
an inability to increase fatty acid oxidation in a cell despite adequate leptin production and normal binding of leptin to cell surface receptors
640
How do allosteric effectors regulate enzymatic activity?
by binding at sites other than the active sites, causing conformational changes in the enzyme
641
How many Da are in 1 amino acid?
110 Da
642
What is succinate-ubiquinone reductase?
an oxidoreductase found in the inner membrane of the mitochondria in eukaryotes
643
What is the name of the small mobile electron carrier that accepts electrons from the iron-sulfur centers, becoming reduced to ubiquinol?
ubiquinone
644
What does the wobble hypothesis state?
the first two nucleotides on the mRNA codon require traditional (Watson-Crick) base pairing with their complementary nucleotides on the tRNA codon but the third nucleotide on the codon may undergo less stringent base pairing in a non-Watson-Crick manner
645
What is the citric acid cycle?
a metabolic process that combines oxaloacetate with acetyl-CoA to make citrate
646
True or False: Threonine is converted to succinyl-CoA
True
647
The reactions that convert succinyl-CoA to malate are part of what cycle?
the citric acid cycle
648
Where does the citric acid cycle occur?
mitochondria
649
Where does gluconeogenesis occur?
in the cytosol
650
What is name of the liver enzyme that controls gluconeogenesis?
fructose-1,6-bisphosphatase
651
Malate must first become what to become phosphoenolpyruvate?
oxaloacetate
652
Oxaloacetate must react with what to become citrate?
acetyl-CoA
653
Apoenzymes and holoenzymes are ___ _____ of the same enzyme
two forms
654
What are zymogens?
enzymes that are initially synthesized in an inactive form to prevent them from acting on potential substrates in the wrong cellular component
655
When are zymogens activated?
when a portion of their polypeptide chain is cleaved
656
When does covalent catalysis occur?
when an enzyme temporarily forms one or more covalent bonds with its substrate
657
What is an amino acid residue?
an amino acid from which H₂O has been removed upon incorporation into a peptide
658
Enzymes are often part of larger groups that all catalyze [similar or different] reactions by [similar or different] mechanisms
similar; similar
659
Does alternative splicing increase protein diversity or genetic variation?
protein diversity
660
ɑ-helices and β-strands are stabilized by hydrogen bonds between ________ _____ ______, where the ___ group of one amide interacts with the ___ group of another amide
backbone amide groups; N-H; C=O
661
What are the two amino acids known to disrupt ɑ-helices?
glycine and proline
662
What is a ternary complex?
a group of three molecules bound together, generally with at least one of the molecules being a protein
663
Name the two mechanisms ternary complexes may form and describe what they are
ordered, in which the ligands must bind in a specific sequence and random, in which the order of binding does not matter
664
Native PAGE takes place in a polyacrylamide gel in the [presence or absence] of any detergents or reducing agents
absence
665
SDS-PAGE is a PAGE performed in the [presence or absence] of sodium dodecyl sulfate (SDS), a detergent that causes the protein to denature and coats it with a [positive or negative] charge
presence; negative
666
The nucleotide subunits in DNA consist of a deoxyribose sugar linked to a ________ ____ at the __ carbon and _________ ______ at the __ and __ carbons
nitrogen base; 1'; phosphate groups; 3'; 5'
667
The ribose sugar has how many carbons?
5
668
What is the deoxyribose in DNA?
a derivative of ribose in which the hydroxyl group at the 2' carbon has been replaced by a hydrogen atom
669
How do desmosomes provide tensile strength to epithelial cells?
by anchoring the cytoskeletons, specifically the intermediate filaments, of two cells together
670
What are gap junctions?
cell-cell junctions that mediate communication between cells
671
What are tight junctions?
cell-cell junctions that prevent water and solutes from diffusing between cells and across the epithelial cell layer
672
Where does ketogenesis occur and what does it play a critical role in?
in the liver and plays a critical role in energy metabolism when glycogen stores are depleted and blood glucose levels become low
673
Osmotic pressure within capillaries is due to what?
the presence of plasma proteins that cannot easily cross the capillary membrane
674
Digestive proteolytic enzymes are synthesized and secreted from where?
the pancreas, stomach, and small intestine
675
Stereospecific reactions produce what?
chiral molecules in a specific rearrangement
676
What are the two intermediates produced by the citric acid cycle?
D-isocitrate and L-malate
677
What is the first reaction in the citric acid cycle?
the conversion of citrate to isocitrate by the aconitase enzyme through an intermediate called cis-aconitrate
678
True or False: Isocitrate contains two new chiral centers after it is converted from citrate
True, isocitrate contains two new chiral centers after it is converted from citrate
679
Insulin stimulates what?
glycolysis
680
The well-fed state is characterized by what?
the release of insulin in response to high levels of glucose in the blood
681
What are the two ways to inhibit gluconeogenesis?
allosterically activate phosphofructokinase-1 and allosterically inhibit the catalytic activity of the gluconeogenesis enzyme fructose-1,6-bisphosphatase
682
________ _________ can be passed on to offspring during sexual reproduction because parental gametic cells combine to form a zygote
Germline mutations
683
_______ _________ are not passed on to offspring because somatic cells are not directly involved in zygote formation
Somatic mutations
684
An enzyme's turnover number kcat represents what?
the number of substrate molecules converted to product per second by each enzyme in solution under saturating conditions
685
What is the formula for the maximum velocity Vmax of an enzyme-catalyzed reaction?
kcat multiplied by the enzyme concentration [E]
686
A decrease in Kₘ corresponds to what?
a left-shift in the x-intercept
687
The slope of a Lineweaver-Burk plot is equal to what?
the Kₘ/Vmax ratio
688
___________ __________ only bind to the free enzyme
Competitive inhibitors
689
_____________ __________ only bind to the enzyme-substrate complex
Uncompetitive inhibitors
690
_____ __________ bind to both the enzyme and the enzyme-substrate complex
Mixed inhibitors
691
_____________ __________ have equal binding affinities for the free enzyme and the enzyme-substrate complex
Noncompetitive inhibitors
692
What must be done to convert the potential energy of fatty acids into the metabolic currency used by cells?
Free fatty acids are first converted to fatty acyl-coenzyme A molecules
693
Each round of fatty acid shortening produces what?
acetyl-CoA and the cofactors NADH and FADH₂
694
True or False: Lipolysis is part of fat oxidation
False, lipolysis is not part of fat oxidation
695
What happens during the first step in oxidative degradation?
Amino acids undergo a transamination reaction that separates the amino group from the carbon skeleton
696
The amino group is subsequently converted to the end product urea in a series of reactions known as what?
ureagenesis
697
Mitochondrial ATP synthesis is carried out by what?
mitochondrial ATP synthase (complex V)
698
What is mitochondrial ATP synthase?
a protein complex embedded in the mitochondrial inner membrane
699
Mitochondrial ATP synthesis contains a subunit that can exist in what three states?
empty, bound to ADP and Pi, and bound to ATP
700
What happens when [S] increases?
V₀ increases hyperbolically, approaching a plateau at Vmax
701
What is the formula for Michaelis constant Kₘ?
Kₘ = (k₋₁ + kcat)/kₘ
702
A high Kₘ indicates a [low or high] binding affinity
low
703
The stability of a protein can be measured by what?
its ability to remain folded as ambient temperature increases
704
What is the melting temperature (Tₘ)?
the temperature at which 50% of the proteins in solution become denatured
705
A higher Tₘ indicates a [more or less] stable protein
more
706
The pentose phosphate pathway consumes glucose-6-phosphate to make what?
ribose-6-phosphate and NADPH
707
How do oxidoreductases interconvert NAD⁺ and NADH, NADP⁺ and NADPH, or FAD and FADH₂?
by transferring hydride ions or hydrogen atoms
708
Name the two oxidoreductases in the pentose phosphate pathway
glucose 6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase
709
How do antibodies bind to their epitopes?
through noncovalent interactions
710
True or False: Both an antibody and its target are proteins
True
711
What is the net charge of a peptide or protein?
a sum of the charges of its side chains and the charges of the N- and C-termini
712
At physiological pH, the N-terminus is [positively charged or negatively charged] and the C-terminus is [positively charged or negatively charged]
positively charged; negatively charged
713
Genetic leakage may occur if...
hybrid offspring successfully mates with members of either parental species
714
What is genetic leakage?
the transfer of genetic information between different species
715
In X-linked recessive disorders, females express the recessive phenotype only when what?
both X chromosomes inherited from their mother and father have the recessive allele
716
The three assumptions of the Michaelis-Menten equation hold true only during when?
the initial phase of the reaction
717
The free ligand approximation states what?
that substrate concentration [S] is constant during the reaction
718
The steady state assumption states what?
that the concentration of ES remains constant over the course of the reaction
719
The irreversibility assumption states what?
that the reaction proceeds only in the forward direction, and product does not get converted back to substrate
720
The enzymes required for fatty acid oxidation are found where?
in the mitochondria
721
The enzymes for fatty acid synthesis are located where?
in the cytosol
722
What are the names of the amino acids with an alkyl side chain?
alanine, proline, leucine, isoleucine, and valine
723
What are the names of the branched amino acids with an alkyl side chain?
leucine, isoleucine, and valine
724
What are transcription factors?
proteins that alter gene expression through binding DNA upstream from promoter regions
725
What must be found to determine the nucleotide sequence of the molecule from which the cDNA is generated?
the mRNA strand complementary to the given cDNA primer
726
Arachidonic acid is modified by cyclooxygenase and a series of other enzymes to form various 20-carbon, nonhydrolyzable lipids called what?
prostaglandins
727
Prostaglandins act as _________ and _________ signals
autocrine; paracrine
728
Because they act only on nearby cells, prostaglandins produce what?
a localized inflammatory response
729
This picture is the structure of what molecule?
citrate
730
What is citrate?
a six-carbon molecule that is synthesized in the first step of the citric acid cycle when acetyl Co-A combines with oxaloacetate
731
This picture is the structure of what molecule?
pyruvate
732
What is pyruvate?
a three-carbon molecule produced in the cytosol after the final step of glycolysis
733
This picture is the structure of what molecule?
oxaloacetate
734
What is oxaloacetate?
a four-carbon molecule that forms in the last step of the citric acid cycle when malate is oxidized
735
This picture is the structure of what molecule?
ɑ-ketoglutarate
736
What is ɑ-ketoglutarate?
a five-carbon molecule that forms in the citric acid cycle when isocitrate releases CO₂
737
The electron carriers of the ETC normally exist in what state?
steady state
738
Complexes I and II pass electrons from NADH and FADH₂ to ubiquinone (UQ), producing what?
ubiquinol (UQH₂)
739
In complex III, UQH₂ passes the electrons to oxidized cytochrome C, yielding what?
reduced cytochrome c and regenerating UQ
740
The proton concentration is normally higher [inside or outside] the mitochondrial matrix than [inside or outside] it
outside; inside
741
What is decoupling?
when protons are transported across the membrane by means that bypass ATP synthase, the energy released in the process cannot be used to produce ATP
742
What are ligand-gated ion channels?
membrane proteins that facilitate the movement of ions across the membrane
743
Sodium rushes down its _______________ _______, whereas the flow of potassium out of the cell is slowed by the ________ ________ _________
electrochemical gradient; negative membrane potential
744
The influx of sodium causes _____ ______________ of the membrane which, if sufficient in magnitude, crosses the threshold to activate _______-_____ sodium channels and propagate the electric signal
local depolarization; voltage-gated
745
What are positive regulators?
molecules that increase the activity or function of a protein
746
Cysteine (C) residues in proteins and peptides can react with each other to form what?
disulfide bonds
747
Disulfide bonds are commonly present in ______ and _________
dimers; multimers
748
The formation of a disulfide bond occurs through what kind of reaction?
an oxidation-reduction reaction
749
What are microtubules?
structural cytoplasmic filaments composed of tubulin subunits
750
Kinesin moves what?
intracellular cargo along microtubules in anterograde axonal transport
751
Dynein participates in what?
retrograde axonal transport of intracellular cargo
752
True or False: Both sperms and oocytes are haploid cells and contribute the same number of nuclear chromosomes to a zygoteq
True
753
What is oogenesis?
the process by which females produce sex cells called eggs
754
Fertilization becomes possible after what happens?
after the released secondary oocyte has been drawn into the fallopian tube
755
What are fallopian cilia?
small hair-like structures that help propel the fertilized oocyte toward the uterus for implantation
756
What is the citric acid cycle?
the set of reactions that converts citrate to oxaloacetate, which then reacts with acetyl-CoA to regenerate citrate
757
What are the final two steps in the cycle prior to formation of oxaloacetate?
the conversion of succinate to fumarate and the conversion of fumarate to malate
758
What is glycogenolysis?
the degradation of glycogen into individual glucose-6-phosphate units
759
The first step in glycogenolysis produces ____________________, which is then converted to G6P through the enzyme _________________
glucose-1-phosphate; phosphoglucomutase
760
G6P is an intermediate of glycolysis that proceeds through the rest of the pathway, which involves conversion of ______________ to _____________ by the enzyme ______________ ______
3-phosphoglycerate; 2-phosphoglycerate; phosphoglycerate mutase
761
The side chain of histidine is derived from what molecule?
imidazole
762
What is imidazole?
a five-member aromatic ring that contains two nitrogen atoms separated by one carbon atom
763
For a peptide of known composition, in which each amino acid is different from every other amino acid, the number of possible arrangements is what?
n!
764
A lower p-value indicates what?
a lower probability of random chance, and therefore a higher probability that the observed difference is real
765
What is the Michaelis-Menten constant Kₘ?
the substrate concentration at which half of the reaction's maximum velocity is achieved
766
A small Kₘ indicates what?
a strong ES complex because only a small amount of substrate is required to achieve a large amount of complex formation
767
A large Kₘ indicates what?
a weak ES complex that does not readily form
768
The catalytic turnover refers to what?
the rate at which an enzyme-bound substrate is converted to product
769
On a Michaelis-Menten plot, catalytic turnover is reflected in what?
the height of the pleateau that occurs at high substrate concentrations
770
Catalytic efficiency is defined by what and is a measure of what?
the ratio kcat/Kₘ and is a measure of enzyme specificity
771
When substrate concentration [S] is significantly higher than Kₘ, the enzyme essentially operates at what?
maximum velocity Vmax
772
Vmax is [directly or indirectly] proportional to kcat
directly
773
Vmax is [directly or indirectly] proportional to the concentration of enzyme [E]
directly
774
Prokaryotic organisms can be in either what two domains?
the Bacteria or the Archaea domain
775
What four traits do archaea share with bacteria?
they are both unicellular, have a circular chromosome, have no membrane-bound organelles or nucleus, and reproduce asexually via binary fission
776
Why is proline unique among the standard amino acids?
because its R group forms a ring that includes the backbone amino group
777
Because of proline's unique feature, the amino group of the proline backbone has two bonds to carbon, making it a _________ _____
secondary amine
778
What is glycolysis?
a catabolic process that degrades glucose to pyruvate
779
Gluconeogenesis is an ________ process
anabolic
780
Pentose phosphate pathway converts what molecules to what product?
converts glucose and glycolysis intermediates to ribose-5-phosphate
781
The rate of glycolysis is largely controlled by the activity of what enzyme?
PFK-1
782
What activators tightly regulate ATP?
ADP, AMP, and F2,6BP
783
What inhibitors tightly regulate PFK-1?
ATP and citrate
784
For portions of proteins exposed to aqueous environments, [hydrophilic or hydrophobic] side chains interact with polar water molecules through hydrogen bonding and electrostatic interaction
hydrophilic
785
[Hydrophilic or Hydrophobic] residues interact poorly with water
Hydrophobic
786
Phenylalanine has a ________ ____
hydrogen atom
787
Tyrosine has a _______ _____
hydroxyl group
788
On a titration curve, the region near a pKₐ is __________ ____ because the addition of base changes the pH by only a small amount
relatively flat
789
All amino acids have ionizable _______ ___ _____ ______ with pKₐ values near 2 and 9.5, respectively
carboxyl and amino groups
790
What is a molecule that allosterically activates Krebs cycle enzymes to meet the demand for energy?
Acetyl-CoA
791
What is a molecule that allosterically inhibits Krebs cycle enzymes?
NADH
792
A thermodynamically [stable or unstable] bond is a bond that forms during a spontaneous reaction, in which no energy input is needed
stable
793
A thermodynamically [stable or unstable] bond forms during nonspontaneous reactions, which require energy input from another source to proceed
unstable
794
In biological systems, the energy used to form thermodynamically unable bonds often comes in the form of what?
ATP or GTP hydrolysis
795
Bonds that break in slow reactions are said to be ___________ ______
kinetically stable
796
How are nucleotides linked to one another?
by phosphodiester bonds between a hydroxyl group of the sugar base of the nucleotide at the 5′ end and the phosphate group of the adjacent nucleotide at the 3′ end
797
The direction in which a chemical reaction tends to proceed depends on the net free energy change between reactants and products is referred to as what?
the Gibbs free energy change ΔG
798
Why do favorable reactions have negative net free energy changes (-ΔG)?
because the products have decreased free energy relative to the reactants and they proceed spontaneously
799
Unfavorable reactions have [positive or negative] free energy changes and form [more or less] stable products
positive; less
800
Why are reactions with a large free energy change between the products and reactants typically unidirectional?
because the reverse reaction is so unfavorable that it essentially never occurs
801
Competitive inhibitors only bind to what?
free enzyme
802
Uncompetitive inhibitors bind only to what?
the enzyme-substrate (ES) complex
803
Mixed inhibitors bind to what?
both free enzymes and the ES complex
804
Mixed inhibitors that have equal affinity for free enzymes and the ES complex represent a special case called what?
noncompetitive inhibition
805
What is the maximum velocity Vmax the product of?
the product of the number of active sites (total enzyme concentration [Etot]) and the rate at which each site converts substrate to product (turnover number kcat)
806
What is the maximum velocity Vmax the product of?
the number of active sites (total enzyme concentration [Etot]) and the rate at which each site converts substrate to product (turnover number kcat)
807
What is catalytic efficiency?
the ratio of the kcat to the Michaelis constant Kₘ.
808
Where do the majority of cellular catabolic reactions occur?
in the mitochondria
809
Fatty acids are degraded to acetyl-CoA by what process in the mitochondria?
β-oxidation
810
What is the formula for the Michaelis-Menten equation?
V₀ = (Vmax [S])/(Kₘ + [S])
811
Na⁺ is reabsorbed from the filtrate moving through the nephron in what structure?
loop of Henle
812
What does Chargraff's rules state?
for any double-stranded DNA sample, a 1:1 nucleotide ratio of pyrimidines to purines must exist
813
What is the molecular weights of dNMPs in decreasing order?
deoxyguanosine (dGMP), deoxyadenosine (dAMP), deoxythymidine (dTMP), and deoxycytidine (dCMP)
814
Steroid hormones are derived from what?
cholesterol
815
Cholesterol has a characteristic four-ring backbone, which is synthesized from five-carbon subunits called what?
isoprenes
816
Two isoprenes join together to form what?
a monoterpene
817
Six isoprenes can join to form a triterpene called what?
squalene
818
After several steps, squalene cyclizes and forms what?
cholesterol
819
What are triacylglycerols?
a class of lipids that function as energy storage lipids
820
Triacylglycerols can be catabolized to produce what?
ATP
821
The esterification of a cholesterol removes the hydrophilic hydroxyl group and replaces it with what?
a hydrophobic acyl tail
822
The replacement of a hydrophilic hydroxyl group with a hydrophobic acyl tail changes the molecule from an amphipathic cholesterol to what?
a hydrophobic cholesteryl ester
823
The rate of an enzymatic reaction is [directly or indirectly] proportional to the concentration of enzyme present in the reaction
directly
824
Wen the active sites on an enzyme are saturated, an increase in [enzyme or substrate] concentration will change the reaction rate
enzyme
825
Enzymes facilitate chemical reactions [with or without] being altered by them
without
826
True or False: Enzymes do not appear on either side of the balanced equation
True
827
The rate of an enzymatic reaction at any given substrate concentration is described by what?
the Michaelis-Menten equation
828
Maximum velocity Vmax equals what?
the product of kcat and enzyme concentration [E]
829
When the substrate concentration equals the Michaelis constant Kₘ, the reaction proceeds at what?
1/2Vmax
830
What is primary structure?
the sequence of amino acids linked together by peptide bonds
831
Secondary structure consists of what?
local structures such as ɑ-helices and β-sheets stabilized by backbone hydrogen bonds
832
Tertiary and quaternary structures describe what?
the three-dimensional form of a protein, mediated by hydrophobic, ionic, and hydrogen bond interactions
833
In isoelectric focusing, an electric field causes proteins to migrate through what?
a pH gradient
834
The low-pH end of the gradient is placed near the [anode or cathode]
anode
835
The high-pH end of the gradient is placed near the [anode or cathode]
cathode
836
As proteins migrate from low pH to high pH, they [gain or lose] protons and become [more or less] positively charged
lose; less
837
What is the major driving force behind protein folding?
the hydrophobic effect
838
The hydrophobic effect causes what?
hydrophobic residues to be buried on the interior of proteins, preventing water from forming solvation layers
839
What is the isoelectric point (pI) of a protein?
the pH at which the protein is neutrally charged overall and does not migrate in an electric field
840
What happens when the pH is lower than the pI?
the protein becomes protonated and is positively charged
841
What happens when the pH exceeds the pI?
the protein loses protons and becomes negatively charged
842
What is chemical denaturation caused by?
the disruption of hydrophobic interactions in the interior of the protein
843
Cytochrome P450 acts as what?
monooxygenases
844
What are monooxygenases?
where an oxygen atom is inserted into a substrate (the drug of interest), thereby resulting in the oxidation of the substrate
845
What is the function of the enzyme carboxylase?
converts acetyl-CoA to malonyl-CoA through the addition of a carboxyl group to acetyl-CoA
846
True or False: Alanine can be phosphorylated
False, alanine cannot be phosphorylated
847
During prolonged exercise, anaerobic respiration would [increase or decrease] the plasma pH
decrease
848
Adding a negative charge to pilin [increases or decreases] its isoelectric point
decreases
849
True or False: Serine can be modified by a phosphotransferase
True
850
Complex II of the ETC is a flavoprotein that is also known as what?
succinate dehydrogenase
851
Complex II of ETC oxidizes succinate to reduce what?
FAD to FADH₂
852
Fatty acids with an even number of carbons produce ____ as many acetyl-CoA molecules as they have carbons
half
853
Fatty acids with an odd number of carbons produce what in addition to acetyl-CoA?
propionyl-CoA
854
Fatty acids can be oxidized to form what?
acetyl-CoA
855
Unsaturated fatty acids require what to convert cis-bonds to trans-bonds?
isomerization reactions
856
True or False: Saturated fatty acids do require isomerization reactions
False, saturated fatty acids do not require isomerization reactions
857
Nuclear localization sequences serve what function?
signal for the transport of proteins such as transcription factors to the nucleus
858
Polyubiquitin tags serve what function?
target defective or unnecessary proteins for destruction by the proteasome
859
Where are N-linked carbohydrates added?
added to certain asparagine residues of proteins in the endoplasmic reticulum
860
Apoptosis can be caused by what?
certain developmental events, DNA damage, or reactive oxygen species
861
When is apoptosis induced?
when cytochrome C is allowed to leave the mitochondria
862
The cytosol is where cytochrome c activates what?
caspase
863
Primary structure is maintained by what?
peptide bonds
864
Secondary structure is maintained by what?
hydrogen bonds
865
Tertiary structure and quaternary structure are maintained by what intermolecular forces and bonds?
van der Waals forces, hydrogen bonds, ionic bonds, and disulfide bonds
866
Complete denaturation disrupts bonding in all other levels of protein structure except what level of structure?
primary structure
867
Entry into the mitochondrial matrix is tightly regulated by what?
transport proteins in the inner mitochondrial membrane
868
Fatty acids must be activated with ________ _ followed by _________ to enter the mitochondrial matrix
coenzyme A; carnitine
869
Activation requires what?
ATP hydrolysis
870
All viruses contain a protective protein coat called what?
the capsid
871
Viruses that contain only a capsid as an outer layer and are able to survive in harsh conditions are known as what?
non-enveloped or naked viruses
872
Viruses with a phospholipid bilayer surrounding the viral capsid are referred to as what?
enveloped viruses
873
True or False: Enveloped viruses are more susceptible to changes in environmental conditions
True
874
What are retroviruses?
enveloped, positive-sense, single-stranded RNA viruses that convert their RNA genomes into double-stranded DNA using the enzyme reverse transcriptase
875
What do retroviruses do in their lysogenic cycles?
they enter the nucleus and integrate their reversed transcribed DNA with the host genome
876
Why are assays with purified proteins useful?
because they can isolate variables
877
Binding affinity can be measured by what?
the dissociation constant Kd
878
A low Kd corresponds to what?
higher binding affinity
879
In western blot analysis, a thick, dense band indicates what?
more protein and higher affinity
880
Binding interactions [absorb or release] heat
release
881
What happens as a protein becomes saturated with ligand?
additional ligand is unable to induce more binding
882
Changes in the binding properties of a protein can alter what?
the Kₘ value
883
What is shown on a Lineweaver-Burk plot?
Kₘ is the negative reciprocal of the x-intercept and Vmax is the reciprocal of the y-intercept
884
Enzymatic reactions typically behave as what kinds of reactions?
zero-order or first-order reactions
885
What does the null hypothesis (H₀) theorize?
there is no difference between 2 groups
886
How does the alternative hypothesis (Hₐ) rival the null?
by supposing that a difference does exist
887
When do disulfide bonds form in proteins?
when two cysteine residues are oxidized to form cystine
888
Enzymes that catalyze oxidation-reduction reactions are collectively known as what?
oxidoreductases
889
Some proteins require what in order to function?
cofactors
890
Tightly bound cofactors are called what?
prosthetic groups
891
A curve with a sigmoidal shape is indicative of what?
a cooperative process
892
What types of cells are typically highly proliferative?
epithelial cells that line the gastrointestinal tract
893
True or False: Methionine has a sulfhydryl group
False, methionine does not have a sulfhydryl group
894
True or False: Cysteine has a sulfhydryl group
True
895
What would be the major pathway that is activated if the electron transport chain is shut down?
glycolysis
896
True or False: The reactions catalyzed by complexes I-IV are coupled to one another
True
897
ATP, the end product of glycolysis, downregulates through ________ ____________ of the activity of phosphofructokinase-1
feedback inhibition
898
In order to maintain a higher concentration of chlorine ions inside the cell, the ions must be moved into the cell [along or against] their concentration gradient, which [does require energy or does not require energy]
against; does require energy
899
What happens if potassium ion channels are blocked?
the membrane would fail to repolarize, extending the length of the action potential and simulating excessive muscle contractions
900
Ubiquitination targets what?
a protein for degradation by a proteasome
901
Disulfide bonds implicate what?
the thiol groups of cysteine residues
902
Posttranslational modification of proteins such as histone acetylation is analyzed by what?
Western blotting
903
Vasopressin regulates the fusion of aquaporins with the apical membranes of what?
collecting duct epithelial cells
904
What are the myelin-forming cells in the peripheral nervous system?
Schwann cells
905
What are the myelin-forming cells in the central nervous system?
oligodendrocytes
906
Phosphoenolpyruvate is a product of what?
glycolysis
907
The central nervous system which includes the brain, is derived from what germ layer?
ectoderm
908
The heart, kidney, and skeletal muscle are derived from what germ layer?
mesoderm
909
Competitive inhibition can be determined through rate experiments by applying the principles of what equation?
the Michaelis–Menten equation
910
What can be determined by keeping enzyme concentration constant, varying substrate concentration, and either including or excluding the inhibitor?
the effect of the inhibitor on the Vmax and apparent Kₘ of the reaction
911
What is the one letter code for aspartate?
D
912
Both glutamate and aspartate have what?
a negatively charged side chain
913
What is necessary to confirm that a small molecule induces the formation of integrase tetramers from integrase dimers?
visualize the proteins in their native state
914
Use of a denaturing agent will disrupt what?
the interactions between monomers
915
Use of a reducing agent only will disrupt what?
any disulfide bonds
916
What amino acid contains a side chain with an amide group?
glutamine
917
A deamidation reaction releases what?
NH₃
918
What is the name of the molecule depicted?
GTP
919
During an action potential, what determines the state of membrane polarization and propagation of the action potential?
the opening and closing of voltage-gated channels
920
If voltage-gated K⁺ channels are downregulated, repolarization would occur more [slowly or quickly], resulting in neuron [hypoexcitability or hyperexcitability]
slowly; hyperexcitability
921
What are telomeres?
highly repetitive stretches of noncoding DNA sequences at the ends of a chromosome
922
True or False: Telomeres do encode gene products
False, telomeres do not encode gene products
923
Certain biomolecules such as vitamins and the essential amino and fatty acids cannot be synthesized in the human body and must be obtained through what?
the diet
924
Where are water-soluble vitamins excreted?
in the urine
925
Where are fat-soluble vitamins stored in?
adipose and other fatty tissues
926
DNA replication is a ________________ process that results in each double helix containing one parental strand and one newly synthesized daughter strand
semiconservative
927
DNA polymerase synthesizes each new daughter strand by using what as a template?
a parental strand
928
At or near physiological pH, amino acid backbones predominantly exist as what?
zwitterions
929
Nucleophilic amino acids contain side chains with atoms that donate electrons when they are [protonated or deprotonated]
deprotonated
930
How do phosphatases catalyze the dephosphorylation of their substrates?
by hydrolysis, producing inorganic phosphate
931
How do kinases catalyze the phosphorylation of their substrates?
by transferring organic phosphate from a donor molecule
932
How do kinases and phosphatases often regulate biological processes?
by counteracting each others' effects
933
What does the turnover number kcat of an enzyme-substrate system represent?
the number of reactions catalyzed per second per enzyme under saturating conditions
934
How can the turnover number kcat be calculated?
by dividing Vmax by the total enzyme concentration [E]
935
Restriction enzymes cleave DNA molecules at specific sites known as what?
restriction sites
936
Each enzyme has a unique restriction site and may cut the DNA such that what is left on the end of the strand?
overhang or sticky end
937
What is Northern blotting?
a technique used to detect and measure the concentration of a specific RNA sequence in a cell or tissue sample
938
Proteins are often purified on what?
chromatography columns
939
Ion-exchange columns separate molecules by what?
charge
940
Size-exclusion columns separate molecules by what?
size
941
Affinity columns isolate what?
molecules that bind a particular ligand
942
What are the key principles of the cell theory?
cells comprise the structures of all living organisms and are individual units of life, cells reproduce by dividing themselves, and cell genomes are composed of DNA that can be passed from parent cells to daughter cells
943
What is ribose?
a five-carbon sugar that must adopt the furanose form to be incorporated into the nucleotide triphosphates
944
Full reduction of water requires what?
four electrons
945
How many copies of a two-electron carrier NADH would be required to fully reduce oxygen?
two copies
946
How many copies of a one-electron carrier reduced cytochrome c would be required to fully reduce oxygen?
four copies
947
The citric acid cycle includes how many oxidative steps?
four oxidative steps
948
Each oxidative step of the citric acid cycle is coupled to what?
the reduction of an electron carrier
949
What is the function of allosteric effectors?
they bind proteins at one site and induce a conformational change at another site
950
What are post-translational modifications?
covalent additions of non-amino acid groups to proteins
951
Phosphorylation occurs almost exclusively at what?
the hydroxyl groups of serine, threonine, and tyrosine residues
952
What are oncogenes?
mutated forms of genes involved in cell cycle progression that transform normal cells into cancer cells
953
Tumor suppressor genes regulate, pause, and inhibit cell cycle progression to ensure what?
damaged DNA is repaired
954
In cancerous cells, mutations [activate or inactivate] tumor suppressor genes and [activate or inactivate] oncogenes
inactivate; activate
955
What are the three parameters that influence the thermodynamic stability of the DNA duplex?
DNA length, pH, and salt concentration
956
High salt concentration of the solution [increases or decreases] double helix stability
increases
957
Decreased salt concentration of the solution [increases or decreases] double helix stability
decreases
958
What are enantiomers?
molecules with identical molecular formulae that differ in the configuration of every stereocenter
959
What is the enantiomer of a D-sugar?
the L-form of the same sugar
960
What is a glycosidic bond?
a bond between the anomeric carbon of a carbohydrate and any other biomolecule
961
How can a single carbohydrate participate in many glycosidic bonds?
by linking to the anomeric carbons of other carbohydrates, allowing a high level of diversity among carbohydrate chains
962
The fluidity of a cell membrane is largely dependent on what?
the lengths of the fatty acyl tails in the bilayer and on the number of double bonds in each tail
963
Why do short chains with double bonds yield the highest fluidity?
because they participate in the fewest intermolecular interactions with neighboring lipids
964
Nucleotide bases can be identified by what?
by their ring structure and by the number of Watson-Crick hydrogen bond donors and acceptors
965
Adenine and guanine are [purines or pyrimidines], whereas thymine and cytosine are [purines or pyrimidines]
purines; pyrimidines
966
Adenine and thymine have how many donors and acceptors?
one donor and one acceptor each
967
Guanine has how many acceptors and donors?
one acceptor and two donors
968
Cytosine has how many acceptors and donors?
two acceptors and one donor
969
How can the total number of nucleotides in an mRNA molecule be calculated?
by multiplying the number of amino acids in the protein by the number of nucleotides in a codon
970
What is the p-value?
the probability of observing a result due to chance alone, assuming that the null hypothesis is true
971
What value of p is considered statistically significant?
≤ 0.05
972
What value of p is not considered statistically significant?
p > 0.05
973
What is Vmax?
the maximum possible rate of an enzymatic reaction when a given concentration of enzyme is present
974
In a Michaelis-Menten graph, [S] is significantly [smaller or larger] than [E] at every [S] measured
larger
975
Vmax occurs only when what?
when the concentration of substrate [S] is high enough that all enzyme active sites are bound
976
Anabolic processes require energy input, which is typically provided by what?
by cleaving phosphodiester bonds in nucleotide triphosphates
977
What is the result of the cleavage of phosphodiester bonds?
they either release the γ- and β-phosphates as pyrophosphate while the ɑ-phosphate remains attached to the NTP
978
True or False: Alanine is similar in size to serine
True
979
What would be the best control against the variable of enzyme autophosphorylation?
the enzymes alone without substrate
980
True or False: Alanine participates in α helices and β sheets extensively
True
981
True or False: Alanine has a potential site for hydrogen bonding
False, alanine does not have a potential site for hydrogen bonding
982
The kcat is used to describe what?
the rate-limiting step of catalysis under saturating conditions of substrate
983
Traditional Michaelis–Menten kinetics describes what kind of dependence of V₀ on substrate concentration?
a hyperbolic dependence
984
The strength of the binding depends on what?
the overall charge of the peptide
985
Peptides with a lower net charge would elute at a [lower or higher] salt concentration than peptides with a higher net charge
lower
986
Na⁺K⁺ ATPase is an example of what kind of transport?
primary active transport
987
How does primary active transport work?
it uses a chemical energy source like ATP to move solutes against their concentration gradient
988
How does secondary active transport work?
it uses one electrochemical gradient to move different molecules against their own concentration gradients
989
This picture is the structure of what amino acid?
lysine
990
Fasting leads to what?
glycogen breakdown and gluconeogenesis
991
Continued fasting leads to what?
the production of ketone bodies by sustained fatty acid oxidation
992
βOHB is a component of what?
ketone bodies
993
Reducing SDS gels separate multimer subunits by what?
size
994
Identical subunits migrate the [same or different] distance and form [a single band or multiple separate bands]
same; a single band
995
Distinct subunits migrate the [same or different] distance and form [a single band or multiple separate bands]
different; multiple separate bands
996
What are protein domains?
distinct, independently folding regions of polypeptide chains that generally carry out distinct functions
997
Ligand binding by a protein domain is measured by what?
the dissociation constant Kd
998
A high value of Kd corresponds to [low or high] affinity for the ligand
low
999
True or False: Different molecules can enter the citric acid cycle at different points
True
1000
The number of electron carriers produced depends on what?
the number of oxidative steps remaining in the cycle from the point of entry
1001
Oncogenes are mutated or expressed at abnormally [low or high] levels
high
1002
How do oncogenes contribute to cancer development?
by promoting cell growth/proliferation or suppressing apoptosis
1003
Tumor suppressor genes which induce programmed cell death are [activated or inhibited] in cancerous cells
inhibited
1004
DNA polymerase I proofreads DNA and normally has exonuclease activity in the 5'-3' as well as the 3'-5' direction that allows it to perform what function?
to remove primers and damaged or incorrect bases at the ends of the strand
1005
Base excision repair and nucleotide excision enzymes have [endonuclease or exonuclease] activity to remove damaged bases and mismatched nucleotides from the [middle or end] of a DNA strand, respectively
endonuclease; middle
1006
Almost all carbohydrates found in nature are in what configuration?
the D configuration
1007
Almost all amino acids found in nature are in what configuration?
the L configuration
1008
In their linear form, monosaccharides contain what functional groups and how many of them?
multiple alcohol groups and one carbonyl group
1009
For aldoses, the carbonyl is [an aldehyde or a ketone] whereas for ketoses, the carbonyl is [an aldehyde or a ketone]
an aldehyde; a ketone
1010
True or False: All monosaccharides contain at least one primary alcohol
True
1011
True or False: Most monosaccharides contain at least one secondary alcohol
True
1012
Glycosidic bonds serve what purpose?
they link the anomeric carbon of a carbohydrate to another molecule, such as a lipid, protein, a nitrogen base, or another carbohydrate
1013
The anomeric carbon has how many bonds to oxygen?
two bonds to oxygen
1014
For aldoses, the anomeric carbon is always on what carbon?
carbon 1
1015
For ketoses, the anomeric carbon is always on what carbon?
carbon 2
1016
What is the complementary color to yellow?
purple
1017
What is the wavelength of the color purple?
360 nm
1018
Protonation of the oxygen atom in glucose makes this substance a [better leaving group or worse leaving group]
better leaving group
1019
True or False: The SDS-PAGE conditions denature the protein and eliminate quaternary structure
True
1020
This picture shows the structure of what molecule?
cytosine that has been methylated at the C5 position
1021
The use of histine tagging and a nickel column is a form of what type of chromatography?
affinity chromatography
1022
The protein with the smallest mass is the one that has the [least or greatest] electrophoretic mobility in SDS-PAGE under non-reducing conditions
greatest
1023
Each mole of [NADH or NAD⁺] can reduce a mole of disulfide bonds
NADH
1024
Largest negative net charge implies what?
the presence of a large quantity of negatively charged amino acids
1025
A reducing agent is used during SDS-PAGE for what purpose?
to cleave disulfide bonds
1026
Phosphodiester bonds serve what purpose?
they link adjacent nucleotides in DNA
1027
True or False: Phosphodiester bonds contribute to the stabilization of protein structure
False, phosphodiester bonds do not contribute to the stabilization of protein structure
1028
The slope of the Lineweaver–Burk plot is equal to what?
Kₘ/Vmax
1029
True or False: Uncompetitive inhibitors do not alter the slope of the Lineweaver–Burk plot
True
1030
Uncompetitive inhibitors bind their target enzymes only when what occurs?
when the substrate is first bound to the enzyme
1031
At higher substrate concentrations, the uncompetitive inhibitor will work most effectively when the substrate concentration is the [lowest or highest]
highest
1032
An increase in the inhibitor concentration results in [increased or decreased] enzyme binding and inhibition
increased
1033
What are signal sequence domains?
protein domains required for proteins that are directed toward secretory pathways
1034
What are the only elements that vary in different cells?
nuclear factors
1035
Nuclear factors can confer what?
both temporal and spatial regulation of their target genes
1036
Glutamine and asparagine are [polar or nonpolar] amino acids
polar
1037
Polar and charged amino acids most likely interact with what?
water molecules in cytosol
1038
True or False: Polar and charged amino acids are involved in protein-protein interactions
False, polar and charged amino acids are not involved in protein-protein interactions
1039
Hydrophobic amino acids contribute to the formation of what?
protein oligomers
1040
Different isoforms of proteins are expressed from single genes through what process?
alternative splicing of exons of the primary transcript
1041
Hydrophilic amino acids are typically found on the [inside or outside] of proteins
outside
1042
Hydrophobic amino acids exist in the [interior or exterior] of proteins
interior
1043
When polar or charged amino acids are exposed to water, they preferentially form hydrogen bonds with what types of molecules?
water molecules
1044
ɑ-helices have how many amino acids per turn?
3.6 amino acids per turn
1045
ɑ-helices are stabilized by what?
hydrogen bonds between carbonyl and amide groups
1046
Where is proline most often found?
in linker regions or at sharp turns due to its structural rigidity
1047
Glycine tends to disrupt helices due to what?
its excessive flexibility
1048
The standard Gibbs free energy, ΔG°, describes what?
whether a reaction favors products or reactants
1049
A negative ΔG° indicates what?
that products are favored
1050
A positive ΔG° indicates what?
that reactants are favored
1051
The equilibrium of a process such as protein folding may be shifted by denaturing agents such that the reaction shifts from what?
favoring folded proteins to favoring unfolded proteins
1052
Cells take up their surrounding environment via what process?
endocytosis
1053
What are the three mechanisms of endocytosis?
phagocytosis, pinocytosis, and receptor-mediated endocytosis
1054
Enveloped viruses can also enter cells by doing what?
by fusing their membrane with the membrane of the cell
1055
Uncompetitive inhibitors bind only to what?
the enzyme-substrate complex
1056
How do uncompetitive inhibitors affect an enzymatic reaction?
by decreasing both the Vmax and Kₘ by the same factor, resulting in an unchanged Vmax/Kₘ ratio
1057
An increase in y-intercept on a Lineweaver-Burk plot corresponds to [an increase or a decrease] in Vmax
a decrease
1058
If enzyme concentration is constant in all experiments, then Vmax corresponds to what?
the turnover number kcat
1059
The activity of an enzyme is greatest at the _______ __ of that enzyme
optimal pH
1060
The activity of an enzyme [increases or decreases] at pH values that are significantly lower or higher
decreases
1061
What are proenzymes or zymogens?
the inactive forms of enzymes that require post-translational modifications to become activated
1062
What is proteolytic cleavage?
a post-translational modification that involves the breakdown of proteins into shorter polypeptides or amino acids by enzymes known as proteases
1063
What is the Hill coefficient?
a quantitative measure of cooperativity
1064
Enzymes in which n﹥1 display what?
positive cooperativity and have sigmoidal dependence on substrate concentration
1065
Enzymes where n = 1 or n﹤1 exhibit what?
no cooperativity or negative cooperativity and exhibit hyperbolic kinetics
1066
What is a reflex?
an involuntary response to a stimulus that does not require input from the brain
1067
Reflexes are mediated by what?
reflex arcs
1068
What are reflex arcs?
neuronal pathways that include a sensory neuron, an effector neuron, and possibly an interneuron
1069
What are the reactants needed to generate fatty acid chains during lipid synthesis?
acetyl-CoA, NADPH, and ATP
1070
What pathway generates the NADPH needed to reduce the carbonyl groups from each molecule of acetyl-CoA that is added to a fatty acid chain?
the pentose phosphate pathway
1071
What happens during β-oxidation?
long-chain fatty acids are activated with coenzyme A and shuttled by enzymes from the cytoplasm to the mitochondrial matrix
1072
What is the rate-limiting step of fatty acid oxidation?
the conversion of fatty acyl-CoA molecules to fatty acylcarnitine by carnitine palmitoyltransferase I
1073
The pyruvate dehydrogenase complex catalyzes what reaction?
he decarboxylation reaction that converts pyruvate to acetyl-CoA
1074
How does insulin stimulate lipid synthesis?
by activating the major enzymes involved in fatty acid production: pyruvate dehydrogenase complex, acetyl-CoA carboxylase, and fatty acid synthase
1075
Pyruvate dehydrogenase converts what?
pyruvate produced from glucose to acetyl-CoA
1076
Where is acetyl-CoA transported for fatty acid synthesis?
to the cytoplasm
1077
Protein catabolism refers to what?
the breakdown of polypeptide chains and proteins into individual amino acids to produce ATP, glucose, or new proteins
1078
How do transamination reactions generate ɑ-keto acids from amino acids?
by transferring -NH₃⁺ group to ɑ-ketoglutarate, which is converted to glutamate
1079
What are glucogenic amino acids?
amino acids that can enter gluconeogenesis
1080
Ketogenic amino acids are converted directly to what?
acetyl-CoA
1081
Acetyl-CoA that enters the citric acid cycle or be used to form what?
ketone bodies
1082
What happens to pyruvate in the absence of oxygen?
it is reduced to lactate to regenerate NAD⁺
1083
What is the Lineweaver-Burk equation?
a rearrangement of the Michaelis-Menten equation that converts enzyme kinetic plots into linear plots
1084
What is the slope of the Lineweaver-Burk equation?
Kₘ/Vmax
1085
What is the y-intercept of the Lineweaver-Burk equation?
1/Vmax
1086
Inhibitors that bind free enzyme E exclusively are [competitive or uncompetitive] inhibitors and cause an [increased or decreased] Kₘ
competitive; increased
1087
Inhibitors that bind enzyme-substrate ES complex exclusively are [competitive or uncompetitive] and cause a [increased or decreased] Kₘ
uncompetitive; decreased
1088
What are mixed inhibitors?
they have characteristics of both uncompetitive and competitive inhibitors and may cause an increase, decrease, or no change in Kₘ, depending on whether they favor binding to E or ES
1089
Pyruvate is reduced to what?
lactate
1090
Longer DNA strands are held together by [more or less] hydrogen bonds, meaning that [more or less] energy is required to denature the double-stranded DNA
more; more
1091
Guanine has a [higher or lower] molecular weight than adenine
higher
1092
The lysine side chain can form isopeptide bonds by reacting with what?
a carboxylic acid group
1093
During conversion of α-ketoglutarate to oxaloacetate in the citric acid cycle, how many molecules of NADH and FADH₂ are generated?
2 molecules of NADH and one molecule of FADH₂ are generated
1094
What enzyme catalyzes the final step of both gluconeogenesis and glycogenolysis?
glucose 6-phosphatase
1095
True or False: RNA polymerase is used in cDNA cloning
False, RNA polymerase is not used in cDNA cloning
1096
What are the starting materials in gluconeogenesis?
lactate, oxaloacetate, and α-ketoglutarate
1097
Activation of the G protein promotes what?
the dissociation of bound GDP and its exchange for GTP on the α subunit
1098
Glycogen is formed by glycosidic bonds between glucose molecules through what?
α(1→4) linkage linearly and α(1→6) linkage at branch point
