Class Two Flashcards
1
Q
what is a monosaccharide
A
single carbohydrate molecule aka simple sugar
2
Q
monosaccharide general formula
A
CnH2nOn
3
Q
bond between two sugar molecules
A
glycosidic linkage
4
Q
glucose + fructose
A
sucrose
5
Q
galactose + glucose
A
lactose
6
Q
characteristics of a glycosidic linkage
A
covalent bond
formed in a dehydration reaction (requires enzymatic catalysis)
7
Q
difference between alpha and beta glycosidic linkages
A
alpha: anomeric C is pointing down (below the plane)
beta: anomeric C is pointing up (above the plane)
8
Q
what is glycogen
A
polysaccharide
energy storage for animals, thousands of glucose units joined together
9
Q
what is starch
A
same as glycogen but for plants
10
Q
what is cellulose
A
polymer of cellobiose
11
Q
how to turn polysaccharides → monosaccharides? is it favoured?
A
hydrolysis
thermodynamically favoured
12
Q
why is hydrolysis of polysaccharides important?
A
allows for the monosaccharides to enter metabolic pathways & be used for energy by the cell
13
Q
mammalian enzymes can’t hydrolyze…? and what is the exception?
A
B-glycosidic linkages
can digest lactose with lactase
14
Q
lactose malabsorbers
A
people without lactase (most people naturally stop making this enzyme after breast feeding)
their lactose ends up in the colon → causes gas + diarrhea
15
Q
why is the high activation energy of polysaccharide hydrolysis relevant
A
use enzymes as gatekeepers - when we need it, we use it
if the Ea was very low, the polysaccharides would hydrolyze spontaneously - very unstable
16
Q
the oxidation of glucose is accompanied by..
A
the reduction of high energy-electron carriers
17
Q
what is NAD+
A
nicotinamide adenine dinucleotide
18
Q
what is FAD
A
flavin adenine dinucleotide
19
Q
how do NAD+ and FAD work
A
they accept high-energy electrons during redox reactions (forming NADH and FADH2)
they are later oxidized when they deliver the electrons to the ETC
20
Q
main function of NAD+ and FAD
A
generation of the proton gradient that is used to generate ATP
21
Q
glucose is oxidized to produced CO2 and ATP in a 4 step process..
A
glycolysis, pyruvate dehydrogenase complex, Krebs cycle & electron transport/oxidative phosphorylation
22
Q
what happens in glycolysis
A
glucose molecule is oxidized + split into 2 pyruvate molecules
23
Q
net surplus from glycolysis
A
2 ATP (ADP + Pi) and 2 NADH (NDH+ + H+)
24
Q
first step of glycolysis
A
phosphorylation of glucose (ATP → ADP: phosphate goes to glucose)
25
enzyme required for the first step of glycolysis
hexokinase
26
2nd & 3rd steps of glycolysis
isomerization of G6P → F6P
phosphorylated again (ATP → ADP) to F1,6bP
27
enzyme required for the 3rd step of glycolysis
phosphofructokinase
28
how much energy for each glucose molecule in glycolysis
4 ATP and 2 NADH
| (half for each pyruvate molecule)
29
what do you NEED to start glycolysis
a bit of ATP
30
what catalyses the first step of glycolysis & how is it inhibited?
hexokinase (phosphorylation of glucose → G6P)
G6P feedback inhibits hexokinase
31
when is NADH produced & how many steps? (glycolysis)
aldehyde is oxidized to a COOH
only happens in one step!
32
when is ATP converted to ADP in glycolysis
everytime a phosphate is added to a substrate
33
when is ADP made into ATP in glycolysis
every time a phosphate comes off a substrat
34
why is the step with PFK important
transfer of the phosphate group is thermodynamically favourable so its basically irreversible
once you get to this step, you're committed to glycolysis
F1,6bP is only used in glycolysis
35
what is the biochemical valve of glycolysis
PFK
36
what is the committed step of glycolysis
conversion of F6P → F1,6bP (with PFK)
37
what happens to F1,6bP
split into 3 carbon molecules that is converted to pyruvate with the production of NADH and ATP
38
PFK and ATP relationship
ATP is an allosteric regulator of PFK
high levels of ATP → slowed glycolysis
too little ATP (or none) → no glycolysis (it is still a reactant)
39
limited NAD+ stimulate or inhibit glycolysis
inhibition - need NAD+ as a substrate to produce NADH
40
anaerobic conditions & NAD+
all the NAD+ gets converted to NADH
41
importance of fermentation
regenerates NAD+ in anaerobic conditions - allows glycolysis to continue in the absence of oxygen
42
how does fermentation work
use of pyruvate as the acceptor of the high energy electrons form NADH
43
examples of NADH as the high energy electron acceptor
reduction of pyruvate to ethanol (beer making)
reduction of pyruvate to lactate in muscle cells
44
why is there a limit to anaerobic respiration
the ethanol and lactate produced builds up + acts like a poison
45
how does liver deal with lactate from muscle
exported from muscle cell to liver
when oxygen becomes available, liver converts lactate back to pyruvate (makes NADH)
excess NADH is used to make ATP in oxidative phosphorylation
46
where does glycolysis occur
in the cytoplasm
47
where does the PDC occur
innermost compartment of the mitochondria - the matric
48
where does the Krebs cycle occur
innermost compartment of the mitochondria - the matrix
49
oxidative decarboxylation
molecule is oxidized to release CO2 and produce NADH
50
pyruvate → activated acetyl unit
activated = not free floating, attached to coenzyme A
51
CoA-SH bond
the bond between sulfur and the acetyl group is high energy → makes it easy for it to transfer the acetyl fragment into the Krebs cycle
52
how is acetyl-CoA formed
pyruvate + coenzyme A → oxidized → acetyl-CoA
53
what is a prosthetic group
a cofactor that is tightly bound to an enzyme
54
prosthetic group in PDC
thiamine pyrophosphate (TPP) - at one of its active sites
55
what is the thiamine in thiamine pyrophosphate
vitamin B1
56
what happens if the PDC and Krebs cycle is shut down
glycolysis would increase to try to maintain ATP levels
57
what would happens in thiamine deficiency
PDC and Krebs cycle = shut down
58
overview of Krebs cycle
takes the 2 carbon unit from acetyl-CoA, combines it with oxaloacetate to release 2 CO2, NADH & FADH2
59
acetate fragment of acetyl-CoA + oxaloacetate →
citrate (2 + 4 → 6 carbon)
60
where is OAA derived from
previous round of Krebs cycle (recycled)
61
first stage of Krebs cycle
oxaloacetate + acetyl CoA + H20 → citric acid + CoA-SH + H+
62
second stage of Krebs cycle
citrate is further oxidized to release CO2 and produced NADH with each oxidative decarboxylation
63
product of stage 2 of Krebs cycle
succinyl-CoA
64
what happens in the third stage of Krebs
succinyl-CoA is turned into OAA so the cycle can continue
65
what does GTP do in the third stage of Krebs
a high energy phosphate bond is produced directly as GTP
66
what does GTP eventually do
transfer its high energy phosphate bond to ADP to make ATP
67
FADH2 vs NADH
similar but FADH2 produces less ATP
68
after the Krebs cycle, what are the remaining products
glycolysis: 2 ATP and 2 NADH per glucose (net)
PDC: 2 NADH per glucose
Krebs: 6 NADH, 2FADH2 and 2 GTP per glucose
69
characteristics of the outer membrane of mitochondrion
smooth + contains large pores formed by porin proteins
70
characteristics of the inner membrane of mitochondrion
impermeable even to small molecules (H+)
densely folded into cristae
71
where are the enzymes of PDC/Krebs cycle located
matrix
72
where are the enzymes of the ETC and oxidative phosphorylation found
bond to the inner mitochondrial membrane
73
2 main goals of ETC/OP
deoxidize all the electron carriers reduced in the previous steps
store energy in the form of ATP
74
where are the NADH from glycolysis found and where do they have to go
found in the cytoplasm, need to go to the matrix so they can donate electrons to the ETC
75
how is the proton gradient set up in prokaryotes
by membrane bound ATPase
76
differences between OP in eukaryotes vs prokaryotes
eukaryotes use their inner mitochondrial membrane for OP
prokaryotes don't have mitochondria - they use their cell membrane
77
what is oxidative phosphorylation
oxidation of high energy electron carriers (NADH & FADH2) coupled to the phosphorylation of ADP → ATP
78
what is an ETC
group of 5 electron carriers
79
what are cytochromes
3/5 of the electron carriers on the ETC
large, embedded din the inner membrane & have heme groups
80
NADH dehydrogenase
first carrier in the ETC, receives electrons from NADH (which is oxidized to NAD+)
81
NADH dehydrogenase aka..
coenzyme Q reductase
82
ubiquinone
receives electrons from NADH dehydrogenase
small + mobile
83
ubiquinone aka..
coenzyme Q
84
cytochrome C reductase
receives electrons from ubiquinone
aka B
one of the big ones
85
cytochrome C
receives electrons from cytochrome C reductase
86
cytochrome C oxidase
aka C
last member of the ETC
87
what do the large membrane bound proteins in the ETC do
pump protons out of the matrix into the intermembrane space
88
each molecule of NADH provides the energy to produce __ ATP molecules
2.5
10 protons for 4 ATP
89
each molecule of FADH provides the energy for __ ATP
1.5
90
what does the glycerol phosphate shuttle do
brings the NADH from glycolysis in the cytoplasm → mitochondria
91
where is the NADH shuttled
directly to ubiquinone (like FADH2)
92
cytosolic NADH vs matrix NADH ATP
cytosolic: makes 1.5 molecules
matrix: makes 2.5
93
why do prokaryotes make more ATP from each glucose
they don't have to transport their cytosolic NADH (takes up energy)
94
ATP yield from eukaryotes vs prokaryotes
eukaryotes = 36 ATP/glucose
prokaryotes = 38 ATP/glucose
95
why does gluconeogenesis occur
dietary sources of glucose are unavailable & no glycogen or glucose from the liver
96
first step of gluconeogenesis
CO2 + pyruvate → pyruvate carboxylase → oxaloacetate
\*need ATP hydrolysis for this process
97
2nd step of gluconeogenesis
oxaloacetate is decarboxylated & phosphorylated to form PEP
\*this process needs PEP carboxykinase (PEPCK)
98
what does fructose-1,6-biphosphatase do
catalyzes the removal of a phosphate group
fru-1,6-bisP → fru-6-P
99
what does glucose-6-phosphatase do
glu-6-P → glucose
irreversible process
100
why is the dephosphorylation of glucose-6-P required
so glucose can be released from the liver
phosphorylated glucose is charged and cannot cross the cell membrane
101
what does gluconeogenesis
4 ATP, 2 GTP and 2 NADH
102
what is reciprocal control
the same molecule regulating 2 enzymes in opposite ways
seen in glycolysis and gluconeogenesis
103
heavily regulated enzymes in glycolysis/gluconeogenesis
PFK and F-1,6-BPase
104
how are PFK and F-1,6-BPase regulated
allosterically regulated by glycolytic intermediates that activate one enzyme while inhibiting the other
105
examples of enzymes that exert reciprocal control
AMP and F-2,6-BP
106
how does F-2,6-BP work
stimulates PFK (which stimulates glycolysis)
inhibits fru-1,6-bisPase (inhibits gluconeogenesis)
107
insulin effects on F-2,6-bP
stimulates it → stimulates PFK → stimulates glycolysis
108
glucagon effects on F-2,6-bP
inhibits it → inhibits fru-1,6-bisPase → inhibits gluconeogenesis
109
how is glycogen made
glucose-6-P → phosphoglucomutase → glucose-1-P
glu-1-P is activated with UTP to form UDP-glucose which is added to the growing glycogen polymer by glycogen synthase
110
why does skeletal muscle lack glucose-6-P
keeps the glucose phosphorylated and unable to leave the muscle cell
111
insulin simulates..
glycolysis and glycogenesis
112
purpose of the pentose phosphate pathway
diverts glucose-6-phosphate from glycolysis to form NADPH, ribose-5-P and glycolytic intermediates
113
what is formed during the oxidative phase of PPP
NADPH and ribose-5-P
114
what is formed during the non-oxidative phase
glycolic intermediates
115
G6PDH in the PPP
primary point of regulation
the product (NADPH) acts via negative feedback to inhibit the enzyme
116
deficiency of G6PDH
limits the ability of RBCs to eliminate ROS → cell death & renal/hepatic complications
117
3 roles of lipids
in adipose cells, triglycerides store energy
in cellular membranes, phospholipids constitute a barrier between intracellular & extracellular environments
cholesterol is the building block for hydrophobic steroid hormones
118
soaps are..
the sodium salts of fatty acids
amphipathic (hydrophobic & hydrophilic regions)
119
what is saponification
soap is produced by base-catalyzed hydrolysis of triglycerides from animal fat into fatty acid salts (soaps)
120
why do fat molecules have more energy content than carbohydrates
fats are much more reduced → oxidizing them releases more energy
121
most common phospholipids in eukaryotic cells
phosphatidylcholine and phosphatidylethanolamine
122
role of phosphatidylcholine
lipid component of lung surfactant → reduces surface tension
123
role of phosphatidylinositol
signal transmission across cell membranes
124
what is squalene and why is it important
triterpene (6 isoprene units)
utilized in the manufacture of steroids & earwax
125
example of a terpenoid
Vitamin A
126
example of a polycyclic amphipath
cholesterol
127
where are the receptors for steroid hormones found
located within cells
128
what is a sphinolipid
structured the same as phospholipids but the backbone is sphingosine instead of a glycerol
129
significant sphingolipid in humans
sphingomyelin - component of the myelin sheath around neurons
130
what is a wax
long chain fats esterified to long chain alcohols
extremely hydrophobic, form waterproof barriers
131
what are fat soluble vitamins
absorbed with dietary fat and stored in adipose/liver
132
what are the 4 fat soluble vitamins
A D E K
133
characteristic of the 4 fat soluble vitamins
ring structures
134
vitamin A
terpenoid, essential for vision/growth
135
vitamin D
derived from cholesterol, regulates calcium and phosphate
136
vitamin E
group of compounds (tocopherols, methylated phenols)
antioxidant
137
most active vitamin E
alpha-tocopherol
138
vitamin K
coenzyme for the activation of clotting proteins
139
characteristics of prostaglandins
belong to the group of molecules known as eicosanoids
have a 5 membered ring
140
roles of prostaglandins
regulate SM contraction, BV diameter
decrease acid secretion and increase mucus secretion
141
how are fatty acids activated
fatty acid + ATP → acyl adenylate
acyl adenylate + HS-CoA → acyl CoA + AMP
142
end result of fatty acid (beta) oxidation
acetyl-CoA
143
why does ketogenesis occur
generation of ketone bodies
when glycogen stores are exhausted and blood glucose falls a lot
144
what are ketone bodies generated from
acetyl-CoA
145
when can ketogenesis occur when there IS enough glucose
if the glucose is present but cannot enter the cell (type 1 diabetic with no insulin shots)
146
diabetic ketoacidosis
acidic ketone bodies
fatigue, confusion and fruity breath
147
what is the committed step of fatty acid synthesis
activation of acetyl CoA in a carboxylation reaction
148
what can individual AAs be broken down into
an amine and a carbon skeleton
149
what can come from an amine (broken down from AA)
urea and nitrogen containing compounds (nucleotide bases)
150
what can come from a carbon skeleton (broken down from AA)
glucose and acetyl CoA
151
how are fatty acids activated
addition of coenzyme A (need 2 ATP)
152
fatty acid oxidation - acetyl CoA
breaks off the fatty acid and goes to the Krebs cycle
153
how many times does a fat go through the beta oxidation cycle
1 less than the number of 2-carbon units
154
what happens if there is a double bond (fatty acid oxidation)
isomerase shifts the double bond to the right place
155
why do unsaturated fats give off less energy
no FADH2 created since a double bond isn't created
156
where does fatty acid synthesis take place
cytosol of liver cells
157
how to turn acetyl CoA to malonyl CoA
add HCO3- (just need another C)
process takes 1 ATP
158
first step of fatty acid synthesis
acetyl CoA attaches to ACP subunit of fatty acid synthase → acetyl ACP & CoA
malonyl CoA + ACP → malonyl ACP + CoA
159
maximum length of fatty acid during synthesis
16 Cs
160
where does fatty acid oxidation occur
mitochondrial matrix
161
linked to __ in fatty acid oxidation
CoA
162
linked to __ in fatty acid synthesis
ACP
163
coenzymes involved with fatty acid oxidation
NAD+ and FAD
164
coenzymes involved with fatty acid synthesis
NADPH
165
fatty acid oxidation goal
generate ATP
166
fatty acid synthesis energy
requires ATP
167
formation of ketone bodies
acetyl CoA → acetoacetate → hydroxybutyrate and acetone
\*all three are ketone bodies
168
basic amino acids have a ___ charge
+1
169
acidic amino acids have a ____ charge
-1
170
side chain of asparate contains..
a carboxylate group
171
GTP is in the family of..
nucleotides
172
actin is a \_\_\_\_
microfilament
173
what cleaves peptide bonds
proteases
174
DNA mutation that results in a change to the nucleotide sequence but no change to amino acid primary structure
silent
175
chromosomes are proofread and repaired following duplication in which stage of the cell cycle
G2
