Biochem 2 Flashcards
1
Q
what are the enzymes involved in the 3 irreversible steps in glycolysis in order
A
hexokinase
phosphofructokinase
pyruvate kinase
2
Q
what converts glucose into glucose-6-phosphate
A
hexokinase
Mg2+
ATP
3
Q
what converts fructose-6-phosphate into fructose-1,6-biphosphate
A
phosphofructokinase
ATP
4
Q
function of pyruvate kinase
A
converts phosphoenolpyruvate into pyruvate
ADP into ATP
5
Q
in terms of Gibbs why does glycolysis have 3 irreversible steps
A
each reaction has a very large negative delta gibbs
6
Q
difference between a cofactor and a coenzyme
A
a cofactor is any non-protein component on an enzyme
a coenzyme is an organic cofactor
7
Q
why is the 2834KJ/mol of free energy from the oxidation of glucose not all converted into heat
A
biological systems cannot utilise heat energy
no single step requires that much energy release
the energy is released in steps
8
Q
where does glycolysis occur
A
cytosol
9
Q
products of glycolysis
A
2 pyruvate
2 NADH + 2H
2ATP
10
Q
name the coenzymes involved in glycolysis
A
ATP/ADP
NADH/NAD
11
Q
what is glycerol converted into in glycolysis
A
intermediate - dihydroxyacetone phosphate
then may be converted into pyruvate
12
Q
what is dihydroxyacetone converted into in gluconeogenesis
A
glucose-6-phosphate
13
Q
difference between a kinase and a phosphatase
A
kinase - phosphorylate
phosphatase - dephosphorylate
14
Q
what transport protein carries glucose across a membrane
A
GLUT2
15
Q
what converts glucose-6-phosphate into fructose-6-phosphate
A
phosphoglucose isomerase
16
Q
function of aldolase and what step is it involved in
A
cleaves fructose-1,6-biphosphate into
dihydroxyacetone phosphate (DHAP)
glyceraldehyde-3-phosphate (GAP)
reversible reaction - step 4 of glycolysis
17
Q
what is step 5 of glycolysis
A
triosephosphate isomerase
converts DHAP (dihydroxyacetone phosphate) into GAP (glyceraldehyde-3-phosphate)
reversible reaction
18
Q
outline step 6 of glycolysis
A
GAP dehydrogenase
converts GAP (glyceraldehyde-3-phosphate) into 1,3-biphosphoglycerate
reversible
19
Q
outline step 7 of glycolysis
A
phosphoglycerate kinase
converts 1,3-phosphoglycerate into 3-phosphoglycerate
reversible
20
Q
step 8 of glycolysis
A
phosphoglycerate mutase
3-phosphoglycerate into 2-phosphoglycerate
reversible
21
Q
what step in glycolysis is enolase involved in and what is its function
A
step 9
converts 2-phosphoglycerate into phosphoenol-pyruvate
reversible
H2O by-product
22
Q
under anaerobic conditions how many ATP is produced for every molecule of glucose converted to lactate/alcohol
A
2 ATP
23
Q
where does the electron transport chain occur in prokaryotic organisms
A
cell membrane
24
Q
how does pyruvate reach the matrix
A
porins from the cytoplasm into the intermembrane space
mitochondrial pyruvate carrier (MPC) through the inner membrane into the matrix
25
what happens to pyruvate in the mitochondrial matrix, and what does it
is converted into acetyl CoA
| pyruvate dehydrogenase
26
what happens when there is an excess of glucose in the presence of co-enzyme A
used for the synthesis of fatty acids in the cytosol
27
what converts pyruvate into acetyl-CoA
pyruvate dehydrogenase complex
28
in the bridge between glycolysis and the TCA cycle what enzyme is used in E1 and what is its prosthetic group and what does it do
pyruvate dehydrogenase
thiamine pyrophosphate
converts lipoamide into lipoate
29
in the bridge between glycolysis and the TCA cycle, what enzyme and prosthetic group is used in E2, and what happens
dihydrolipoyl transacetylase
lipoamide and Coenzyme-A (CoA -SH)
converts CoA-SH into acetyl-CoA
30
enzyme and prosthetic group of E3, and what happens
dihydrolipoyl dehydrogenase
FAD/NAD
FAD carries H+ from reduced lipoamide to NAD+ to convert it into NADH
31
step 1 of the TCA cycle, reactants, enzyme and product
acetyl-CoA and oxaloacetate
citrate synthase
citrate
32
TCA step 2
the tertiary alcohol in citrate is coverted into a secondary alcohol forming isocitrate
enzyme - aconitase
33
TCA step 3
isocitrate dehydrogenase converts isocitrate into oxalosuccinate
isocitrate dehydrogenase converts oxalosuccinate into alpha-ketoglutarate
34
TCA step 4
alpha-ketoglutarate
alpha-ketoglutarate dehydrogenase#
succinyl-CoA
35
TCA step 5
succinyl-CoA
succinyl-CoA synthetase
succinate
36
TCA step 6
succinate
succinate dehydrogenase
fumarate
37
TCA step 7
fumarate
fumarase
malate
38
TCA step 8
malate
malate dehydrogenase
oxaloacetate
39
how much ATP is produced from glycolysis and 2 pyruvate entering the Krebb's cycle
glycolysis - 8
| TCA cycle - 30
40
what enzymes are involved in converting malate into aspartate and what is the purpose of this
malate dehydrogenase converts into oxaloacetate
transaminase converts oxaloacetate into aspartate
reduces NAD+ into NADH
41
what is the purpose of converting aspartate into malate
oxidises NADH into NAD+
42
how many ATP are produced per NADH produced by the malate-aspartate shuttle
3
43
where does the malate-aspartate shuttle generally occur and give an example
tissues that have relatively low energy requirements
| liver
44
in the glycerol-phosphate shuttle, what causes the oxidation and reduction of NAD/FAD
conversion of glycerol-3-phosphate into dihydroxyacetone phosphate reduces FAD+ into FADH2
the opposite reaction oxidises NADH into NAD+
45
where is the glycerol-phosphate shuttle used
metabolically active tissues
| neurons, muscles
46
how many ATP is produced per NADH in the glycerol-phosphate shuttle and why
2 ATP
| one less ATP ensures the reaction does not reverse
47
where is FADH2 produced
inner membrane
48
function of complex I
```
oxidises NADH
transfers electrons to ubiquinone
becomes ubiquinol (QH2), transfers electrons to complex III
pumps 4 into the intermembrane space
```
49
function of complex III
transfers electron from one mobile electron carrier to the other
receives electron from ubiquinol and transfers it to
2 cytochrome-c, 1 electron each
pumps 4 protons into intermembrane space
50
function of complex IV
transfers the electrons from the cytochrome-c proteins into the matrix
pumps 2 protons into the intermembrane space
reduces O2 into H2O, O2 final electron acceptor
51
function of complex II
converts succinate to fumarate
| oxidises FADH2 into FAD+
52
in glycogen how often does a branch occur
8-12 glucose
53
how many glucose in a glycogen and its diameter
120,000
| 10-40nm
54
function of phosphorylase and its prosthetic group
```
breaks bonds via phosphorylating them
pyridoxal phosphate (PLP)
```
55
what can phosphorylase not phosphorylate on a glycogen
1-6 glycosidic bonds
| 1-4 bonds that are within 4 glucoses of a branch point
56
how is a branch in glycogen hydrolysed
phosphorylase trims the branch to 4 glucose
transferase transports 3 glucose from the branch onto the main chain
1,6-glucosidase hydrolyses the last 1-6 glycosidic bond
57
enzymes involved in glycogen into glucose
glycogen phosphorylase into phosphorylated glucose
| phosphoglucomutase converts Pi-G into glucose
58
if the glycogen phosphorylase reaction is reversible, why doesn't it for glycogen anabolism
because the concentration of Pi is much larger than
| G-1-P
59
how is glycogenesis achieved
phosphoglucomutase - converts G-6-P into G-1-P
UDP-glucose phosphorylase - converts G-1-P into UDP-glucose using UTP
glycogen synthase - converts UDP-glucose into glycogen
60
function of glycogen synthase
creates 1-4 bonds onto existing chains
can't create a chain
can't create 1-6 bonds
61
function of glycogenin
creates 8 unit primer chain
| is extended by glycogen synthase
62
function of branching enzyme
binds to chains that are 11+ units long
cuts of 7 units
reattaches the heptamer via a 1-6 bond
done 4+ units away from the existing branch
63
what does an omega-4 fatty acid indicate
the first double bond in the chain is at the 4th carbon
64
functions of elongases and desaturases
elongases - adds 2 carbons to fatty acid chain
| desaturase - adds a double bond to the chain
65
what can humans not do in terms of desaturase
add double bonds lower than omega 9
66
how are triglycerides transported in the bloodstream and why
they are packaged into lipoproteins because they are too hydrophobic on their own
67
what is lipogenesis and where does it occur
digested triglycerides are re-esterified in the gut mucosa
68
what enzyme re-esterifies triglycerides
acyltransferase
69
where is lipoprotein lipase located and what is its function
lumenal side of endothelial cells
| cleaves fatty acids which enter the cell
70
function of G-3-P dehydrogenase
converts G-3-P into DHAP
71
function of acyltransferase
converts glycerol-3-phosphate into lysophosphatidic acid
72
what converts lysophosphatidic acid into phosphatidic acid
1-acylG-3-P acyltransferase
73
function of phosphatidic acid phosphatase
converts phosphatidic acid into diacylglycerol
74
what is the last step of lipogenesis, substrate, product and enzyme
diacylglycerol
triacylglycerol
diacylglycerol acyltransferase
75
function of human serum albumin (HSA)
releases fatty acids so they can travel to the outer membrane of the mitochondria
76
what makes acetyl-CoA
fatty acid + coenzyme A
77
what must CoA do to cross the inner mitochondrial membrane
CoA must be swapped into carnitine
78
what transports acetyl-carnitine
translocase antiporter
79
what happens once acyl-carnitine enters the mitochondrial matrix
the acyl chain re-attaches to to CoA
80
what do free fatty acids bind to in adipose tissue
human serum albumin
81
how do fatty acids enter the outer membrane of the mitochondria
are released from HSA
82
what are the products of beta-oxidation
acetyl CoA
| acyl CoA
83
how does the chain length of a fatty acid affect how many cycles of beta oxidation is required
increases cycles required with chain length
84
what is a ketone body comprised of
3 acetyl CoA joined together
85
how is acetone removed from the body
breath
sweat
urine
86
what are the 3 destinations for amino acids in pool
protein synthesis
direct use
breakdown and redeployment
87
what converts an amino acid into a keto acid and vice verca
aminotransferase
88
what is the first step of fatty acid anabolism
condensation reaction between
activated malonyl and activated acyl
to form a C-C bond between them
89
what is step 2 in fatty acid anabolism
reduction reaction to convert a C=O into COH
90
step 3 in fatty acid anabolism
dehydration reaction to convert a C-C bond into a C=C bond
91
step 4 of fatty acid anabolism
reduction reaction to add a H to C-H to from C-H2
92
what is the purpose of the 4 fatty acid anabolism steps
the final product is an activated acyl group thats been elongated by 2 carbons, then that same acyl group can enter the reaction process again to elongate further
93
how many cycles of the fatty acid anabolism chain must be completed to form palmitic acid
6
94
what amino acids breakdown into pyruvate
```
alanine
cysteine
glycine
serine
threonine
tryptophan
```
95
what amino acids breakdown into acetyl CoA
isoleucine
leucine
tryptophan
96
what amino acids breakdown into acetoacetyl CoA
```
leucine
lysine
phenylalanine
tyrosine
tryptophan
```
97
what amino acids breakdown into alpha-ketoglutarate
```
arginine
glutamine
glutamate
histidine
proline
```
98
amino acids that breakdown into succinyl CoA
isoleucine
methionine
valine
threonine
99
amino acids that break down into fumarate
aspartate
phenylalanine
tyrosine
100
amino acids that breakdown into oxaloacetate
asparagine
| aspartate
101
step 1 of gluconeogenesis
conversion of pyruvate into OAA
| via pyruvate carboxylase
102
step 2 of gluconeogenesis
conversion of F-1,6-biphosphate into F-6-phosphate
| via F-1,6-biphosphatase
103
the 3rd irreversible reaction of gluconeogenesis
glucose-6-phosphate converted into glucose
| via glucose-6-phosphatase
104
why can tissues that don't contain glucose-6-phosphatase not export glucose
because glucose-6-phosphate cannot pass through the plasma membrane
105
where is glucose-6-phosphatase located
plasma membrane
106
what is the cori cycle and where is it located
conversion of lactate into glucose and vice versa
| liver
107
what amino acid does muscle catabolism release
alanine
108
what is pyruvate converted into in the cori cycle and via what
alanine
via alanine aminotransferase
reversible reaction
109
define Keq
ratio of product to substrate in equillibrium
110
what is the mass action ratio
ratio of product to substrate in a cell
111
what does it mean if the MAR is roughly equal to the Keq
that the reaction is close to equilibrium
112
what does it mean if the reaction is rate limiting in the cell
MAR is roughly = to Keq
113
for the rate limiting step, how large is the mas action ratio compared to the Keq
100-1000x smaller
114
in a perturb system what does a crossover point mean
a regulatory step
115
what is the preferred fuel for the heart
ketone bodies
116
what is the preferred fuel source of immune cells and the intestines
glutamine
117
what is the only fuel source used for spermatozoa
fructose
118
what is lactate used for in the kidneys
ATP production
119
what % of glucose undergoes glycolysis, glycogen, and become triglycerides
glycolysis - 50-60%
glycogen - 10%
triglycerides - 30-40%
120
name 4 storage organs
liver
adipose
muscle
gut
121
what is the Km of GLUT1/3 and HK1/2/3 in most tissues
low
122
what enzymes have a high Km in the liver
```
GLUT2
HK IV (glucokinase)
```
123
what has a medium and what has a low Km in muscle and adipose tissue
medium - GLUT4
| low - HK II
124
what converts glucose into fat and prevents fat breakdown
insulin
125
what does fructokinase convert fructose into
F-1-P
126
what does F-1-P aldolase convert F-1-P into
glyceraldehyde
127
what converts glyceraldehyde into Gly-3-P
triose kinase
128
what enzyme does F-1-P also stimulate
pyruvate kinase
129
what does an excess of pyruvate lead to
excess acetyl CoA
| FA and TG synthesis
130
what does alcohol dehydrogenase convert ethanol into
acetaldehyde
131
what does aldehyde dehydrogenase convert acetaldehyde into
acetate
132
what enzyme converts acetate into acetyl CoA
acetyl-CoA synthetase
133
during a fasting state what is the metabolic priority of adrenaline and glucagon
increase glycogenolysis and gluconeogenesis
| increase lipolysis and increased glycerol for gluconeogenesis
134
during a fasting state what is the metabolic priority of cortisol
protein degradation
| increase gluconeogenesis
135
during a fasting state how does adrenaline affect muscle tissue
```
increases:
phosphorylase
PFK1
lipoprotein lipase
HS lipase
```
decreases: glycogen synthase
136
during a fasting state how does adrenaline and glucagon affect liver tissue
increase:
phosphorylase
F-1,6-biphosphate
decrease:
glycogen synthase
PFK1
acetyl CoA carboxylase
137
what are the metabolic priorities when starving
preserve functional proteins
| reduce glucose requirements
138
what does muscle store under rest and when intense
rest/mild - glucose
| intense - none
139
what is the preferred substrate for muscle tissue when rest/mild versus intense activity
rest/mild - fatty acids
| intense - glucose
140
how does brown adipose tissue generate heat
by wasting the energy stored in fat
| important in babies
141
what does the activation uncoupling protein 1 lead to
uncoupling of electron transport chain and ATP synthesis
142
what is UCP1 activated by
FFA
143
how is metabolic processes used to in thermogenesis
instead of producing ATP from the electron transport chain, the energy is lost and released into heat
144
what is the reversibility of a drug with covalent effects, and non-covalent
covalent - irreversible
| non-covalent - reversible
145
definition of an agonist
produces a response
146
definition of an antagonist and difference between a pharmacological antagonist and a physiological one
blocks a response, has no action of its own
pharmacological - prevents the action of an agonist at its receptor
physiological - agents which have mutually antagonistic responses but act via different receptors
147
difference between efficacy and potency
efficacy - the size of the response
| potency - the concentration needed for a response
148
how does a partial agonist effect the response curve
lowers the overall efficacy
| lowers the curve
149
how does a competitive antagonist effect the response curve
shifts the response curve to the right
| no overall change to efficacy
150
what agents are blocked by atropine
muscarine
arecoline
oxotremorine
151
what agent is histamine blocked by
mepyramine
152
name the 4 agonists at the skeletal neuromuscular junction and their order of potency
proprionylcholine - 400
butyrylcholine - 150
acetylcholine - 100
valerylcholine - 30
153
what are nicotinic receptors blocked by
d-tubocurarine
154
what are muscarinic receptors blocked by
atropine
155
what type of receptor is the muscarinic receptor
G-protein coupled
156
where are muscarinic receptors located
```
intestinal smooth muscle
heart
blood vessels
salivary glands
CNS
```
157
what type of receptors are nicotinic receptors
ligand-gated ion channels
158
where are nicotinic receptors located
skeletal muscle
ganglia
smooth muscle
159
what is the structure of nicotinic receptors
pentameric
2 alpha
beta gamma
sigma
160
what are the excitatory amino acid transporters
NMDA
AMPA
AP-4
Kainate
161
what are the inhibitory amino acid transporter
muscimol
| baclofen
162
function of GABA
major inhibitory neurotransmitter in the CNS
163
what does histamine sub type 1 produce
vasodilation
| increased vascular permeability
164
what does histamine receptor sub type 2 produce
stimulates gastric acid secretion
165
what does phenylketonuria affect
phenylalanine hydroxylase
166
what chromosome does phenylketonuria affect and the genetic property of the disease
chromosome 12
| autosomal recessive
167
what are the effects of phenylketonuria
mental retardation
organ damage
unusual posture
168
how many people does phenylketonuria affect and what needs to be done for sufferers
1/20,000
| low Phe diet
169
what is a glycogen storage disease
inability to convert glycogen to glucose
leads to:
hypoglycaemia
enlarged liver
170
in glycogen storage disease V what is absent
glycogen phosphorylase
171
what causes hypercholesterolaemia
defect in LDL-R gene
