1201-1400 Flashcards
1
Q
What G protein is stimulated by activated rhodopsin?
A
Gt (transducin), which decreases cyclic guanosine monophosphate (cGMP) and closes the Na+ channels, causing nerve transmission
2
Q
What are the vitamin K-dependent clotting factors?
A
2, 7, 9, and 10
3
Q
What vitamin is connected to selenium (Se) metabolism?
A
Vitamin E
4
Q
What is the activated form of vitamin E?
A
Alpha-tocopherol
5
Q
What elements make up a nucleoside?
A
A base and a sugar
6
Q
What is the most common methylated base?
A
Cytosine
7
Q
DNA is replicated at what phase of the cell cycle?
A
S phase
8
Q
At which end of DNA are new bases added?
A
3’ end
9
Q
What keeps single-strand DNA (ssDNA) from re-annealing during DNA replication?
A
Single-strand (ss) binding protein
10
Q
What enzyme is responsible for producing a single-strand (ss) cut in the DNA to relieve the coil tension?
A
Topoisomerase I (relaxase)
11
Q
What two amino acids are found in high concentrations in the nucleosome?
A
- Arginine 2. Lysine
12
Q
What three bases are pyrimidines?
A
- Cytosine 2. Uracil (only in RNA) 3. Thymidine
13
Q
What enzyme creates a short sequence of RNA to start DNA replication?
A
Primase
14
Q
What type of enzyme is reverse transcriptase?
A
RNA-dependent DNA polymerise
15
Q
What is the direction of transcription?
A
5’ to 3’ direction
16
Q
Where is the TATA box in located eukaryotes?
A
25 bases downstream (-25)(promoter)
17
Q
What causes transcription to stop in eukaryotes?
A
The poly(A) site on the DNA
18
Q
What protein binds to the promoter region in eukaryotes to initiate transcription?
A
TF II D (transcription factor)
19
Q
What part of the 30S ribosome binds to the Shine-Dalgarno sequence?
A
16S subunit
20
Q
What is the start codon for translation?
A
AUG
21
Q
What is the enzyme that activates the amino acids for the tRNA?
A
Aminoacyl-tRNA synthetase
22
Q
What is needed to direct enzymes to a lysosome?
A
Phosphorylation of mannose residues
23
Q
What cofactor is needed for lysyl oxidase?
A
Cu2+
24
Q
What part of the 50S and 60S ribosomal subunit is needed for elongation?
A
Peptidyl transferase
25
In the lac operon: At which site is the repressor gene encoded?
I gene
26
To which site does the repressor protein bind in order to inhibit transcription?
Operator
27
What amplification technique is used to generate a larger amount of DNA?
Polymerase chain reaction (PCR)
28
What test is used to determine whether a gene is expressed?
Northern blotting
29
At what organ in the body is urea produced?
Liver
30
What regulatory proteins work during fetal development to ensure that cells become a specific cell type (If there is a defect here, there can be profound structural mutations.)?
Homeobox genes
31
What is the mode of inheritance in which a trait is seen in every generation and is passed on only by females?
Mitochondrial inheritance
32
What is the name for the process of going from mRNA to proteins?
Translation
33
What are the components of a nucleotide?
A base, a sugar, and a phosphate
34
What enzymes hydrolyze 3'-5' phosphodiesterase bonds from the outside of the strand in?
Exonucleases
35
What type of organisms have monocistronic mRNA?
Eukaryotes
36
In collagen, every third amino acid is this amino acid.
Glycine
37
What form of continuous DNA, used in cloning, has no introns or regulatory elements?
c-DNA, when it is made from mRNA
38
What proteins stimulate a cell to enter the S phase?
Growth factors
39
At what pH is there no net charge on the structure?
pI (isoelectric point)
40
What complex of the ETC contains Cue+?
Complex 4
41
What two shuttles are needed to keep NAD+ in the reduced state?
Malate/aspartate and glycerol-3-phosphate shuttles
42
What vitamin is required for y-carboxylation of many Cat+-binding proteins?
Vitamin K
43
From where is the energy for gluconeogenesis derived?
Ã-Oxidation of fatty acids
44
What amino acid is broken down into N20, causing an increase in eGMP of smooth muscle resulting in vasodilatation?
Arginine
45
What hormone phosphorylates enzymes to decrease their activity?
Glucagon
46
Lack of what enzyme can lead to Wernicke-Korsakoff syndrome through lack of activity in the HMP shunt?
Thiamine pyrophospate (TPP)
47
What enzyme found in the liver catalyzes glycerol to glycerol-3-phosphate?
Glycerol kinase
48
Which shuttle is used to bring fatty acyl CoA from the cytoplasm for ketogenesis?
Carnitine acyl CoA transferase II
49
Which enzyme is deficient in phenylketonuria (PKU)?
Phenylalanine hydroxylase
50
After approximately how many days of a prolonged fast does death occur in humans?
60 days
51
What is the cause of death?
The breakdown of the essential proteins of the heart and brain
52
All the carbons in a fatty acid are derived from what source?
Cytoplasmic acetyl CoA that left the mitochondria as citrate
53
What enzyme is deficient in alcaptonuria?
Homogentisic acid
54
In a diabetic patient, glucose is converted by aldose reductase to what?
Sorbitol (resulting in cataracts)
55
What glycolytic intermediate can be used to synthesize triglycerides and phospholipids?
DHAP
56
What glycolytic enzyme has a high Vmax high Km and low affinity for glucose?
Glucokinase
57
What is the main inhibitor of pyrnvate dehydrogenase?
Acetyl CoA (pyruvate to acetyl CoA)
58
What are the two substrate-level phosphorylations in glycolysis?
1. Pyruvate kinase 2. Phosphoglycerate kinase
59
What are the eight liver-specific enzymes?
1. Fructokinase 2. Glucokinase 3. Glycerol kinase 4. PEPCK 5. Pyruvate carboxylase 6. Galactokinase 7. Fructose-1,6-biphosphate 8. Glucose-6-phosphate
60
In what cycle does glucose go to the muscle, where it is converted to pyruvate and then into alanine before being taken back to the liver?
Alanine cycle
61
In what cycle does glucose go to the muscle, where it is converted to lactate, and then returned to the liver?
Cori cycle
62
What four substances increase the rate of gluconeogenesis?
1. Glucagon 2. NADH 3. Acetyl CoA 4. ATP
63
What enzyme is deficient in a patient who presents with: Liver damage and severe hypoglycemia?
Aldolase B (hereditary fructose intolerance)
64
Jaundice, vomiting, lethargy, cat, galactosemia, and galactosuria?
Galactose 1-phosphate uridyltransferase
65
What three substances stimulate glycogenolysis?
1. Cat+:calmodulin ratio 2. Epinephrine 3. Glucagon
66
What are the two inhibitors of complex I of the ETC?
1. Rotenone 2. Amytai (barbiturates)
67
What are the five factors that constitute the pyruvate dehydrogenase complex?
1. TPP 2. Lipoic acid 3. CoASH 4. FAD 5. NAD
68
What attaches to protons and allows them to enter into the mitochondria without going through the ATP-generating system?
24-Dinitrophenol
69
What are the two decarboxylation steps of the TCA cycle?
1. Isocitrate dehydrogenase 2. a-Ketoglutarate dehydrogenase
70
What are the three inhibitors of complex IV of the ETC?
1. Cyanide 2. CO 3. Azide
71
What three steps of the TCA cycle generate NADH?
1. Malate dehydrogenase 2. Isocitrate dehydrogenase 3. a-Ketoglutarate dehydrogenase
72
What disease presents with weakness and cramps on exercise without an increase in blood lactate levels?
McArdle's disease (muscle glycogen phosphorylase deficiency)
73
NADPH generated from the HMP shunt is used for what?
Fatty acid synthesis, nucleotide synthesis, and glutathione reductase
74
Is linolenic acid an omega-3 or -6 fatty acid?
Omega-3; linoleic is omega-6
75
Is the oxidative reaction of the HMP shunt reversible or irreversible?
Irreversible (G-6-PD and 6-phosphogluconate dehydrogenase)
76
What disease presents with an enlarged liver and kidneys, dwarfism, hypoglycemia, acidosis, and hyperlipidemia?
Von Gierke's disease (glucose 6-phosphatase deficiency)
77
At what three sites can the HMP shunt enter into glycolysis?
1. Fructose-6-phosphate 2. Glucose-6-phosphate 3. Glyceraldehyde-3-phosphate 1
78
Deficiency in the liver glycogen phosphorylase enzyme is known as what?
Hers disease
79
What causes the lysis of red blood cells by oxidizing agents in a glucose-6- phosphate dehydrogenase deficiency?
The lack of glutathione peroxidase activity results in a decrease in NADPH production, leaving glutathione in the reduced state.
80
What disease presents with hepatomegaly and a normal EKG?
Glycogen storage disease, type III (Forbes disease, Cori disease)
81
What apoprotein is on the surface of LDL?
Apoprotein B-100
82
What carries cholesterol from the tissues back to the liver?
HDLs
83
What apoprotein mediates the uptake of remnants by the liver?
Apoprotein E
84
What is the complex needed for acetyl CoA carboxylase?
Biotin, ATP, and G02 (acetyl CoA to malonyl CoA)
85
What are the three tissues where TAGS are produced?
1. Liver 2. Muscle 3. Adipose tissue
86
What delivers cholesterol to the tissues?
LDLs
87
What apoprotein is produced by the intestinal epithelium?
Apoprotein B-48
88
What carries TAGS to the peripheral tissues?
VLDLs
89
How many NADPHs are used per addition of each of acetyl CoA into a fatty acid chain?
2 NADPHs/acetyl CoA
90
What apoprotein activates lipoprotein lipase in the capillary epithelium to hydrolyze TAGS?
Apoprotein C-II
91
What apoproteins are on the surface of IDL?
Apoproteins B-100 and E
92
From which two substances are phospholipids made?
1. DAGs 2. Phosphatidic acid
93
What apoproteins are on the surface of HDL?
Apoprotein A-I, C-II, and E
94
What is needed to produce a double bond in a fatty acid chain in the endoplasmic reticulum?
NADPH, O2, and cytochrome b5
95
What apoprotein activates lecithin cholesterol acyl transferase to esterify cholesterol from tissue?
Apoprotein A-I
96
What apoproteins are on the surface of VLDL?
Apoproteins B-100, C-II, and E
97
At the end of each round of Ã-oxidation, what is released?
Acetyl CoA, FADH, and NADH
98
What two enzymes are vitamin B12 dependent?
1. Homocysteine methyl transferase 2. Methylmalonyl CoA transferase
99
What enzyme is blocked by disulfiram?
Aldehyde dehydrogenase
100
What hormone hydrolyzes TAGS to free fatty acids and glycerol?
Hormone-sensitive lipase
101
What enzyme is deficient in a patient 2 years of age or younger who presents with vomiting, lethargy, coma, hypoketosis, and hypoglycemia following a fast of more than 12 hours?
Medium-chain acyl dehydrogenase
102
What form of alcohol did the patient drink if he became blind as a result?
Methanol (wood alcohol)
103
What regulates the rate of ketone body formation?
The rate of Ã-oxidation
104
What intermediate enables propionyl CoA to enter into the TCA cycle?
Succinyl CoA
105
What sphingolipid is formed by the union of serine and palmitoyl CoA?
Sphingosine
106
What intermediate of cholesterol synthesis anchors proteins in the membranes and forms CoQ?
Farnesyl pyrophosphate (FPP)
107
What is the complex needed for propionyl CoA carboxylase?
Biotin, ATP, and C02
108
What are the three ketone bodies?
1. Acetoacetate 2. Acetone 3. Ã-hydroxybutyrate
109
What type of damage to the kidneys is caused by drinking ethylene glycol (antifreeze)?
Nephrotoxic oxylate stones
110
What is the only sphingolipid that contains choline and p04?
Sphingomyelin (lecithin also, but it is not a sphingolipid)
111
What is the order of fuel utilization in a prolonged fast?
1. Glucose from liver glycogen 2. Glucose from gluconeogenesis 3. Body protein 4. Body fat
112
Sialic acid and amino sugars are needed to produce what sphingolipid?
Ganglioside
113
What vitamin is needed as a cofactor for decarboxylation and transaminase reactions?
Vitamin B6
114
What are the two ways that nitrogen can enter into the urea cycle?
1. Aspartate 2. Carbomoyl PO4
115
What is the only enzyme in the body that uses N5 methyl folate?
Homocysteine methyl transferase
116
What enzyme deficiency will result in an increase in blood ammonia and an increase in uracil and orotate concentrations in both the blood and urine?
Ornithine transcarbamoylase (OTC) deficiency-also called ornithine carbamoyltransverase (OCT) deficiency
117
What amino acid is a precursor of the following substances: Serotonin?
Tryptophan
118
What amino acid is a precursor of the following substances: GABA?
Glutamate
119
What amino acid is a precursor of the following substances: Histamine?
Histidine
120
What amino acid is a precursor of the following substances: Creatine?
Glycine/arginine
121
What amino acid is a precursor of the following substances: NAD?
Tryptophan
122
What amino acid is a precursor of the following substances: N20?
Arginine
123
What enzyme deficiency will result in an increase in blood ammonia, but no increase in uracil concentrations?
Carbamoyl-phosphate synthetase
124
What are the glucogenic and ketogenic amino acids?
Phenylalanine, Tyrosine, Tryptophan, Isoleucine, Threonine
125
What are the three diseases of sphingolipids?
1. Niemann-Pick disease 2. Gaucher's disease 3. Tay-Sachs disease
126
What type of jaundice is seen in Rotor's syndrome?
Conjugated (direct) hyperbilirubinemia
127
What is the pyrimidine intermediate that joins PRPP?
Orotic acid
128
What three amino acids are used to synthesize the purine ring?
1. Glycine 2. Aspartate 3. Glutamine
129
What enzyme is blocked by hydroxyurea?
Ribonucleotide reductase
130
What is the primary end product of purine synthesis?
IMP
131
What enzyme is deficient in hereditary protoporphyria?
Ferrochelatase
132
What are the two precursors of heme?
1. Glycine 2. Succinyl-CoA
133
What enzyme is blocked by 5-FU?
Thymidylate synthetase
134
What disease has a genetically low level of UDPglucuronate transferase, resulting in elevated free unconjugated bilirubin?
Gilbert's syndrome
135
What form of bilirubin can cross the blood-brain barrier?
Unconjugated free bilirubin
136
What substrates are needed to produce carbamoyl P04 (de novo pyrimidine synthesis)?
Glutamine, CO2, and ATP via carbamoyl PO4 synthetase II
137
What enzyme is blocked by methotrexate/trimethoprim?
Dihydrofolate reductase
138
What type of jaundice is seen in Dubin-Johnson syndrome?
Conjugated (direct) hyperbilirubinemia (It is a transport defect.)
139
What form of bilirubin is carried on albumin?
Unconjugated (indirect)
140
In what disease is there a genetic absence of UDPglucuronate transferase, resulting in an increase in free unconjugated bilirubin?
Crigler-Najjar syndrome
141
What enzyme is deficient in acute intermittent porphyria?
Uroporphyrinogen I synthetase
142
What enzyme is deficient in congenital erythropoietic porphyria?
Uroporphyrinogen III cosynthase
143
What amino acid has a pKa of 13?
Arginine
144
What two amino acids have a pKa of 10?
1. Lysine 2. Tyrosine
145
What two amino acids have a pKa of 4?
1. Aspartic acid 2. Glutamic acid
146
What disease has a genetic deficiency in adenosine deaminase?
Severe combined immunodeficiency (SCID)
147
What type of charge does the molecule have if the pH is greater than the pI (isoelectric point)?
A net negative charge
148
In what disease is there a deficiency in hypoxanthine guanine phosphoribosyl transferase (HGPRT)?
Lesch-Nyhan syndrome
149
What is the end product of purine catabolism?
Uric acid
150
What enzyme is deficient in selective T cell immunodeficiency?
Purine nucleoside phosphorylase
151
What substrate builds up in Tay-Sachs disease?
Ganglioside GM2
152
On a Lineweaver-Burke plot, what type of binding has both plots crossing the y-axis in the same spot?
Competitive, reversible inhibition (Vmax is the same, increase Km)
153
What toxin ADP-ribosylates via GS protein to increase CAMP?
Cholera toxin
154
What vitamin derivatives are used for growth and differentiation of epithelium for reproductive and embryonic development?
Vitamin A
155
Light causes isomerization of what in the eyes?
11-cis-retinal to traps-retinal (activated rhodopsin)
156
What are the two actions of calcitonin?
1. Increases Ca2+ excretion from the kidney 2. Increases bone mineralization
157
What causes an increase in bone mineralization and Cat+, as well as P04 absorption from the GI tract and kidney tubules?
Vitamin D
158
On the Lineweaver-Burke plot, what type of binding has both plots crossing the x-axis in the same spot?
Noncompetitive, reversible binding (decrease in Vmax; Km is same)
159
What is the maximum rate possible with a given amount of enzyme?
Vmax
160
To what are intracellular glucose levels inversely related?
cAMP levels
161
Does a saturated fatty acid have double bonds?
No; unsaturated fatty acids have double bonds
162
What two factors cause PTH to be secreted?
1. A decrease in blood Ca2+ 2. A decrease in PO4 concentrations
163
What in the human genome differs in each individual that can serve as an identification marker?
RFLP-restriction fragment length polymorphism
164
What test is used to identify HIV-positive patients?
ELISA-enzyme-linked immunosorbent assay
165
What toxin ADP-ribosylates via G to increase cAMP?
Pertussis toxin
166
What vitamin is essential for normal Ca2+ and P04 metabolism?
Vitamin D
167
What vitamin is deficient in a person who has impaired taste, night blindness, and increased risk for having an abortion?
Vitamin A
168
What bond does an endonuclease cleave?
3', 5' internal phosphodiesterase bond
169
What protein separates base pairs and unwinds the DNA at the replication fork?
Helicase (It is an ATP-dependent enzyme.)
170
What vitamin deficiency would cause liver necrosis and red blood cell fragility?
Vitamin E deficiency
171
What protein catalyzes the formation of the last phosphodiester bond (PDE) between the Okazaki fragments to produce a continuous strand?
DNA ligase
172
What is the hypochromic effect?
Increased absorption as DNA goes from double stranded to single stranded
173
What technique uses DNA for analysis?
Southern blotting
174
In what direction is a new DNA strand made?
5' to 3'
175
What enzyme has a 5' to 3' synthesis activity and a 3' exonuclease activity?
DNA polymerase III
176
What enzyme makes a double-stranded cut through DNA, needs ATP, and introduces negative supercoiling?
Topoisomerase II
177
What eukaryotic DNA polymerase is used for: DNA replication?
a- and delta-polymerase
178
What eukaryotic DNA polymerase is used for: Replication in mitochondria?
gamma-Polymerase
179
What eukaryotic DNA polymerase is used for: DNA repair?
Ã-Polymerase
180
What is the orientation of the gene sequence strand?
5' to 3' (same as RNA)
181
What is the location of the TATA box in procaryotes?
10 bases downstream
182
What binds to the promoter region in procaryotes?
Sigma factor
183
What enzyme has a 5' to 3' synthesis of the Okazaki fragments, 3' exonuclease activity, and 5' exonuclease activity?
DNA polymerase I
184
What type of mutation has the same amino acid coded for, but with a different codonsequence?
Silent mutation
185
At what position of the anticodon does the "wobble" hypothesis occur?
Position 1 of the anticodon (the 5' end)- which is the same as position 3 of the codon (the 3' end)
186
What are the three "stop" codons?
1. UAA 2. UAG 3. UGA
187
What stops transcription in procaryotes?
Rho factor or a hairpin loop
188
What are the three post-transcriptional modifications?
1. 7-methyl guanine cap on the 5' end 2. Addition of the poly(A) tail to the 3' end 3. Removal of introns
189
In what type of mutation is a different codon added, resulting in formation of a different amino acid?
Missense mutation
190
What amino acid is attached to the 3' end of the tRNA in eukaryotes?
Methionine
191
What enzyme makes tRNA and the SsRNA?
RNA polymerase III
192
What structure of a protein describes the interaction among subunits?
Quaternary structure
193
What two amino acids require vitamin C for hydroxylation?
1. Proline 2. Lysine
194
What is determined by the secondary structure of an amino acid?
The folding of an amino acid chain
195
Which mutation has a stop codon put in place of the previous codon?
Nonsense mutation
196
What amino acid is attached to the 3' end of the tRNA in prokaryotes?
f-Methionine
197
What enzyme makes rRNA (barring the 5s subunit)?
RNA polymerase I
198
What is the site of action of cycloheximide?
Peptidyl transferase (60S)
199
What translation factor is blocked by erythromycin?
Elongation factore G (EF-G)
200
What is the charge of the molecule if the pH is less than the pI (isoelectric point)?
A net positive charge
