Exam 2 - Metabolism Flashcards
(185 cards)
1
Q
location of TCA
A
mitochondria
2
Q
location of glycolysis
A
cytosol
3
Q
ATP yield of one cycle of glycolysis
A
7 ATP (given NADH = 2.5 ATP)
4
Q
regulation of glycolysis
A
product inhibition
allosteric control
covalent modulation
5
Q
Fats can be converted to glucose. T/F?
A
F, it can only be converted as far as acetyl CoA due to irreversibility
6
Q
Glycolysis and gluconeogenesis are both regulated at the same time. T/F?
A
F, both processes have different rate-limiting steps
7
Q
Alanine is used as a substrate for glycolysis in the glucose-alanine cycle. T/F?
A
F, it is converted back to pyruvate for use in gluconeogenesis.
8
Q
Glucose to pyruvate conversion requires a lot of energy. T/F?
A
T
9
Q
hormone initiating glycolysis
A
insulin
10
Q
hormone initiating gluconeogenesis
A
glucagon
11
Q
Enzyme:
Fructose-6-P → Fructose-1,6-biP
A
PFK (phosphofructokinase)
12
Q
Enzyme:
Fructose-1,6-bisphosphate → Fructose-6-Phosphate
A
fructose-1,6-biPase
13
Q
Enzyme:
PEP → pyruvate
A
pyruvate kinase
14
Q
absorption pathway of short- and medium-chain FAs
A
enter portal blood directly from enterocytes (readily absorbed)
bound to albumin
oxidized in the liver
15
Q
absorption pathway of long-chain FAs
A
form chylomicrons and lipoproteins
drain into lymphatics via lacteals
enter bloodstream via thoracic duct into SCV
16
Q
lipoproteins with the least and most proteins
A
most: HDL
least: chylomicron
17
Q
lipoproteins with the least and most lipids
A
most: chylomicron
least: HDL
18
Q
lipoproteins with the least and most fats
A
most: chylomicron
least: HDL
19
Q
lipoproteins with the least and most free and esterified cholesterol
A
most: LDL
least: chylomicron
20
Q
lipoproteins with the least and most phospholipids
A
most: HDL
least: chylomicron
21
Q
LDL marker apoprotein
A
Apo B100
22
Q
cofactor for LCAT
A
Apo A-I
23
Q
cofactor for LPL
A
Apo C-II
24
Q
enzyme inhibitors for LPL
A
Apo A-II and Apo C-III
25
ennzyme inhibitor for CETP
Apo C-I
26
ligands for LDL receptor
Apo B100 and Apo E
27
ligand for HDL receptor
Apo A-I
28
apoprotein with highest affinity to LDL receptor
Apo B100
29
enzyme catalyzing RLS in FA oxidation
acyl CoA synthetase
| esterifies FA to CoA
30
net ATP produced from beta oxidation of 14-C saturated FA
formula: 14(n-1) + 10 - 2; where n = C/2
| net ATP = 14(6) + 10 - 2 = 92 ATP
31
sources of acetyl CoA for FA synthesis
oxidative decarboxylation of pyruvate from glucose
oxidative degradation of some proteins
beta-oxidation of long-chain FA
32
sources of cholesterol
dietary - 0.4g/day
| biliary/de novo - 2g/day
33
enzyme regulating cholesterol synthesis
HMG-CoA reductase
34
process involving HMG-CoA synthase and HMG-CoA lyase
ketogenesis
35
glucose hydrolysis intermediate converted to glycerol
DHAP
36
derivatives of cholesterol
corticosteroids
steroid hormones
bile salts and acids
Vit D
37
function of serum albumin
carrier protein for steroids, FAs, thyroid hormones
38
sources of N incorporated into urea during urea cycle
aspartate and ammonia
| majority derived from glutamate
39
links urea cycle to TCA
fumarate
40
Why should essential AA be part of the diet?
The body cannot synthesize essential AA de novo and thus relies on external sources.
41
cofactor to forward homoCys --> Met
Vit B12
42
cofactor to forward homoCys --> Cys
Vit B6
43
possible condition following Vit B12 and B6 deficiency
homocystinuria
44
AA needing supplementation in diet of Px with phenylketonuria
tyrosine
45
impaired pathway in phenylketonuria
phenylalanine --> tyrosine
thus, tyrosine is deficient and needs supplementation in diet
46
principal action of thyroxine
```
increase O2 production
increases metabolism (BMR)
```
47
factor directly related to BMR
lean body mass
48
importance of dietary proteins
provide essential amino acids for protein synthesis
49
suggested food to lower cholesterol
oat bran and other soluble fibers that reduce LDL levels
50
dietary fibers
decrease TAGs
increase stool bulk
improves chyme transmission
51
kwashiorkor
```
grossly underweight (<70% below normal)
edema
loss of pigmentation in hair and skin
hypoalbuminemia
moon facie and wet form
```
52
marasmus
extremely low weight
extreme wasting - loss of fat and muscle
dry form and geriatric face
53
cause of marasmus
calorie, protein, and nutrient deficiency
54
cause of kwashiorkor
protein deficiency despite adequate intake of calories
| e.g. substituting milk for cassava
55
optimal proportion of carbs, fats, and proteins in diet
55~70% carbohydrates
20~30% fat
10~15% proteins
56
glycemic index
measure of blood glucose levels in response to food with respect to a standard food
57
glycemic load
glycemic index * carbohydrate concentration of food
58
food with relatively high glycemic index
bread > pasta and rice
59
biochemical measure of obesity/overnutrition
serum LDL
60
deficiencies resulting in anemia
folic acid
| Vit B12
61
reaction associated with Vit C
hydroxylation - oxidizes the iron
oxidized Vit C is less/no longer effective
62
treatment for megaloblastic anemia from Vit B12 deficiency
folic acid
63
retinal
active form of Vit A
| stored in liver
64
product of B-carotene hydrolysis
retinal
65
Vit D deficiency in children
rickets
66
Vit D deficiency in adults
osteomalacia
67
fat-soluble vitamins
Vit A, D, E, K
68
precursor of thiamine pyrophosphate
Vit B1
69
thiamine
Vit B1
70
riboflavin
Vit B2
71
Vit B6
pyridoxal, pyridoxine, pyridoxamine
72
thiamine deficiency
beri-beri
| Wernicke-Korsakoff Syndrome
73
pellagra
can result from niacin deficiency
| can lead to 3Ds - dermatitis, diarrhea, dementia
74
ascorbic acid
Vit A
75
precursor of lycopene and B-carotene
plant carotenoids
76
reason for regulation of metabolism
energy source does not have the same distribution as energy stores
77
importance of glucose phosphorylation to G6P
keep glucose inside cells
| RLS in glycolysis
78
GLUT4 insulin dependence
insulin dependent
| 1, 2, 3, 5 are insulin INdependent
79
enzyme forming fructose-2,6-biP
Enzyme II
80
effect of phosphorylation of Enzyme II
decrease of fructose-2,6-biP concentration
81
energy change with PEP --> pyruvate
large negative delta-G
82
energy consumption of PEP --> pyruvate
2 ADP
83
location of PEP --> pyruvate
cytosol
84
Catabolic enzymes are usually active when phosphorylated. T/F?
T
| ...and anabolic enzymes are active when DEphosphorylated
85
catabolism
breakdown
oxidation
exergonic
[think: CAT bOx]
86
anabolism
synthesis
reduction
endergonic
87
ATP yield of NADH
2.5 ATP
88
ATP yield of FADH2
1.5 ATP
89
process not involving net influx of energy from other sources
catabolism
| exergonic reaction: releases energy to other sources
90
step involved in substrate level phosphorylation in TCA cycle
succinyl CoA --> succinate
91
ATP produced in ETC by complete glucose oxidation
glycolysis: 2 NADH = 5 ATP
oxidative phosphorylation: 2 NADH = 5 ATP
TCA cycle: 2 FADH2 + 6 NADH = 3 + 15 ATP
total: 5 + 5 + 3 + 15 = 28 ATP
92
predominant glycerol derivative in intestinal lumen after Orlistat discontinuation
2-MAG
93
intermediates of odd-chain FAs entering TCA
succinyl CoA + acetyl CoA
94
What is acetyl CoA converted into for transport into cytoplasm from mitochondria (and v.v.)?
citrate
95
enzyme affected by enteropeptidase deficiency
pepsin
96
Maple Syrup Disease
accumulation of V, I, L
97
amplification
allows small amount of signal molecule to cause an increased intracellular transduction
98
effect of anaerobic glycolysis on GLUT4
increases activity
99
difference of hexokinase and glucokinase
glucokinase: in liver, phosphorylation only at high glucose levels, increased by insulin
hexokinase: in extrahepatic tissues, inhibited by G6P
100
location of pyruvate carboxylase
only in the mitochondria
101
compounds based on tyrosine
```
catecholamines (epinephrine, norepinephrine, dopamine)
melanin
thyroid hormones (T3, T4)
```
102
AA precursor of serotonin
tryptophan
103
factor increasing digestibility and absorption of dietary lipids
longer FA length
104
precursor FA for other FAs
palmitate
105
provides reducing equivalents in lipid synthesis
glucose
106
location of lipid synthesis
cytoplasm
107
characteristics of essential fatty acids
not naturally synthesized by humans
synthesized by plants (and some animals)
help maintain membranes
double bonds at delta-12 and delta-15 (o-6 and o-3)
108
location of double bonds in essential FAs
delta-12
| delta-15
109
omega-3 precursor
linoleic acid
110
entry point of proprionyl CoA into TCA cycle
proprionyl CoA --> succinyl CoA
111
odd-numbered FAs enter glucogenic pathway via ___ (intermediate)
proprionyl CoA
112
Acetoacetic acid and B-hydroxybutyrate are weak acids. T/F?
F, they are rather strong.
113
location of ketogenesis
liver mitochondria
114
substrate used in ketogenesis
acetyl CoA
115
cofactor/s of lysly oxidase (collagen synthesis)
Vit C and iron
116
negative nitrogen balance
N intake < N loss
117
conditions presenting negative nitrogen balance
burns, fevers, wasting diseases, serious injuries
| fasting, malnutrition
118
positive nitrogen balance
N intake > N loss
119
conditions presenting positive nitrogen balance
growth, tissue repair, pregnanacy
120
Athletes usually have lower BMRs (compared to non-athletes). T/F?
F, they have slightly higher BMRs.
121
TCA cycle is purely anabolic. T/F?
F, it has both anabolic and catabolic phases.
122
final common pathway for metabolism of glucose, FAs, and AAs
TCA cycle
123
The TCA cycle produces oxidizing equivalents for the ETC. T/F?
F, it produces reducing equivalents.
124
Carbohydrate energy stores are bulky and not readily available. T/F?
F, they are bulky but they are more readily available.
125
Fat stores are bulky and not readily available. T/F?
F, they are not readily available but compact.
126
Amino acids are glucose sources but have other uses. T/F?
T
127
source of blood glucose replenishment
breakdown of dietary CHO
128
methotrexate
anticancer drug
| primary folate antagonist
129
methorexate mechanism
inhibits reduction of dihydrofolate to tetrahydrofolate (THF, which helps in nucleotide formation)
130
First Law of Thermodynamics
Energy is neither created nor destroyed but converted into other forms.
131
free energy value in spontaneous metabolic reaction
negative free energy value (dG)
132
nervous excitation is (endergonic / exergonic)
endergonic
133
active transport is (endergonic / exergonic)
endergonic
134
muscular contraction is (endergonic / exergonic)
endergonic
135
fuel oxidation is (endergonic / exergonic)
exergonic
136
amphibolic pathway
TCA cycle
137
products of acetyl CoA oxidation in TCA
NADH, FADH2, CO2
138
ATP yield from isocitrate --> fumarate
isocitrate -> a-ketoglutarate + NADH = 2.5 ATP
a-ketoglutarate -> succinyl CoA + NADH = 2.5 ATP
succinyl CoA -> succinate + GTP = 1 ATP
succinate -> fumarate + FADH2 = 1.5 ATP
total = 2.5 + 2.5 + 1 + 1.5 = 7.5 ATP
139
(some) pathways producing reducing e- for ETC
TCA cycle
B-oxidation
aerobic glycolysis
140
used to form H2O at the end of ETC
O2
141
location of ETC
inner membrane of mitochondria
142
Phosphorylation reactions synthesize ATP. T/F?
T
143
Why does muscle contraction increase the rate of oxidative phosphorylation?
ADP concentration is increased.
144
mechanism of hydrogen sulfide
inhibits cytochrome oxidases (in complex IV)
| leads to loss of consciousness and cardiopulmonary arrest
145
result of oxidative phosphorylation uncoupling by dinitrophenol
ATP production stops
| oxygen uptake continues
146
ADP
product of ATP hydrolysis
positive effector for glycolysis and TCA cycle
signals low enery level in the cell
147
final electron acceptor in the ETC
O2
148
direct energy source for ATP synthase to produce ATP
proton gradient established in mitochondria
149
changes in metabolism in the heart following MI
decreased rate of oxidative phosphorylation
increased rate of lactic acid synthesis
increased use of glucose by muscle tissue
150
cellular compartment becoming acidic (filled with H+) during mitochondrial electron transport
space between inner and outer mitochondrial membrane
151
As affinity of the enzyme for substrate decreases, Km also decreases. T/F?
F, substrate affinity and Km are inversely proportional.
152
Km
substrate concentration at 1/2 Vm
| expressed in units of concentration
153
organic precursors of coenzymes
vitamins
154
Noncompetitive inhibition is irreversible. T/F?
F, both competitive and noncompetitive inhibition are reversible.
155
reverses competitive inhibition
addition of excess substrate
156
Reversible inhibition entails covalent bond formation. T/F?
F, reversible inhibition involves noncovalent interactions (H-bonds, hydrophobic interactions, ionic bonds) while irreversible inhibition usually involves covalent bonds.
157
electron acceptor of cyt c oxidase
O2
158
protein directly catalyzing fibrin hydrolysis
plasmin
159
isozymes
enzymes with different AA sequences catalyzing same chemical reaction
(e.g. hexokinase and glucokinase)
160
competitive inhibition
increases Km
inhibitor is usually a structural analog of substrate
via noncovalent interactions
161
function of pyridoxal phosphate as cofactor
amino group carrier
162
organ with highest demand for glucose as fuel
brain
163
Why isn't skeletal muscle glycogen involved in blood glucose regulation?
Only the liver has G-6-Pase which allows glucose release into the blood.
164
counter-regulatory hormones to insulin
glucagon
epinephrine
cortisol
165
Not all enzymes involved in gluconeogenesis are in the cytosol. T/F?
T, some are in the sER and mitochondria.
166
processes regulating glycolysis
```
covalent modification (pyruvate kinase inhibited by high [ATP])
allosteric control (PFK)
hormonal regulation (role of glucagon)
```
167
products of anaerobic glycolysis of 1 glucose
2 ATP + 2 lactate
168
possible Px presentation of insulinoma (insulin-secreting tumor)
obesity
| hypoglycemia
169
products of transamination of aspartate and a-ketoglutarate
OAA + glutamate
170
AA utilized to transport ammonia to the liver
A and Q
171
diet causing high [urea] in urine
very low CHO, very high CHON
172
ketogenic AA
yields acetoacetyl CoA through ketogenesis
exclusively ketogenic: L, K
keto- and glucogenic: W, I, F, T, Y
173
glucogenic AA
yields glucose through gluconeogenesis
| ~all AA except K and L
174
Why is arginine semi-essential?
synthesizable via urea cycle
| required intake dependent on health status and stage of development
175
compounds involved in metabolism of 1-C compounds
THF
SAM
B12 (methylcobalamin)
176
AA donating amino groups for purine synthesis
G, Q, D
177
activated sugar utilized for both purine and pyrimidine de novo synthesis
PRPP
178
deficient enzyme in hyperuricemia
hypoxanthine-guanine phosphoribosyl transferase (HGPT)
179
disorders associated with hyperuricemia
Lesch-Nyhan syndrome
| gout
180
mechanism of allopurinol
inhibits xanthine oxidase (xanthine --> uric acid)
decreases uric acid formation
inhibits purine synthesis
181
indication/s for allopurinol
hyperuricemia
| gout
182
mechanism of methotrexate
```
inhibits DHFR (DHF --> THF)
inhibits synthesis of DNA, RNA, thymidylates, proteins
```
183
indications of methotrexate
cancer
| autoimmune diseases
184
mechanism of 5-fluoroacil
inhibits thymidylate synthase (dUMP --> TMP)
| inhibits RNA synthesis
185
indications for 5-fluoroacil
cancer
