Where are the enzymes of the citric acid cycle primarily situated?
Απάντηση
(A)
The central region of mitochondria
2
What is the first reaction in the citric acid cycle?
Απάντηση
(B)
Combining acetyl-CoA with oxaloacetate
3
Which molecule acts as a catalyst in the citric acid cycle?
Απάντηση
(A)
Oxaloacetate
4
Which citric acid cycle enzyme can also be found outside the mitochondria?
Απάντηση
(C)
a-Ketoglutarate dehydrogenase
5
What is necessary for the α-ketoglutarate dehydrogenase enzyme to function in the citric acid cycle?
Απάντηση
(A)
NAD
6
Assuming a solution contains all citric acid cycle components, excess acetyl-CoA, and is at the right pH, which factor would limit the cycle's speed?
Απάντηση
(D)
Cofactor reduction
7
In the TCA cycle, what enzyme changes oxalosuccinate into α-ketoglutarate?
Απάντηση
(B)
Isocitrate dehydrogenase
8
Which cofactor is essential for the enzyme -ketoglutarate dehydrogenase in the citric acid cycle?
Απάντηση
(A)
Lipoate
9
In the citric acid cycle, which reaction produces a high-energy phosphate through substrate-level phosphorylation?
Απάντηση
(D)
Succinyl CoA ⇌†† α-Succinate
10
Fluoroacetate prevents which reaction in the citric acid cycle?
Απάντηση
(C)
Citrate ⇌†† α-cis-aconitate
11
What substance inhibits the conversion of α-Ketoglutarate into succinyl-CoA?
Απάντηση
(B)
Arsenite
12
How many ATP molecules are produced in a single cycle of the citric acid cycle?
Απάντηση
(B)
12
13
What is the net ATP yield from the complete oxidation of one glucose molecule?
Απάντηση
(D)
38 ATP
14
Which metabolic intermediate can serve as both a starting material and an end product in glucose metabolism?
Απάντηση
(A)
Lactate
15
Which of the following molecules can freely pass through the mitochondrial membrane?
Απάντηση
(B)
Malate
16
Which reaction in the Kreb's cycle does not require a cofactor from the vitamin B group?
Απάντηση
(A)
Citrate ‡† isocitrate
17
Which coenzyme is NOT used in the formation of acetyl-CoA from pyruvate?
Απάντηση
(B)
Biotin
18
In the citric acid cycle, which molecule acts as a carrier?
Απάντηση
(C)
Oxaloacetate
19
Which substance specifically inhibits succinate dehydrogenase?
Απάντηση
(B)
Arsenite
20
Which enzyme in the citric acid cycle is regulated by allosteric control?
Απάντηση
(C)
Fumarase
21
What is the net ATP production from the Rapport-Leubering pathway in red blood cells?
Απάντηση
(A)
0
22
Under aerobic versus anaerobic conditions, what is the approximate ratio of net ATP molecules formed per glucose molecule?
Απάντηση
(C)
18:1
23
Glycogen synthesis utilizes a specific nucleotide of glucose. In the following reaction, what does NuDP represent? NuDP Glucose + glycogen,→ NuDP + glycogen+1
Απάντηση
(C)
UDP
24
Which describes the state of the enzyme phosphoglucomutase during the conversion of glucose 6-phosphate to glucose 1-phosphate?
Απάντηση
(D)
Phosphorylated-dephosphorylatedrephosphorylated
25
Approximately what percentage of the liver's weight is glycogen?
Απάντηση
(A)
6%
26
Which enzyme creates branch points during glycogenesis?
Απάντηση
(A)
Amylo [1→ 4] [1→ 6] transglucosidase
27
In glycogenolysis, which enzyme facilitates the transfer of a trisaccharide unit, exposing a 1→6 branch point?
Απάντηση
(B)
α-[14] α-[14] Glucan transferase
28
Which step in the synthesis of glycogen from glucose is reversible?
Απάντηση
(B)
Glucose 6-phosphate glucose 1-phosphate
29
In which of the following tissues is the enzyme glucose-6-phosphatase, which converts glucose 6-phosphate to glucose, not present?
Απάντηση
(B)
Muscle
30
Which molecule acts as an allosteric activator of glycogen synthase?
Απάντηση
(B)
Glucose-6-Phosphate
31
Which factor suppresses the function of glycogen synthase?
Απάντηση
(C)
Mg2+
32
Which hormone stimulates glycogen synthase function?
Απάντηση
(A)
Insulin
33
What are the distinguishing traits of an active site?
Απάντηση
(D)
Both (A) and (B)
34
A deficiency in which enzyme defines Von Gierke's disease?
Απάντηση
(A)
Glucose-6-phosphatase
35
What enzyme's absence causes Cori disease (Limit dextrinosis)?
Απάντηση
(B)
Debranching enzyme
36
Mc Ardle's syndrome is caused by the lack of which enzyme?
Απάντηση
(B)
Muscle phosphorylase
37
Which enzyme deficiency is associated with Pompe's disease?
Απάντηση
(A)
Lysosomal α-1→4 and 1→6-glucosidase
38
What enzyme deficiency results in Amylopectinosis?
Απάντηση
(B)
Branching enzyme
39
What enzyme is deficient in Her's disease?
Απάντηση
(B)
Liver phosphorylase
40
Tarui disease is linked to the lack of which enzyme?
Απάντηση
(C)
Muscle and erythrocyte phosphofructokinase
41
Which enzyme is involved in the hexose monophosphate pathway?
Απάντηση
(D)
Glucose-6-phosphate dehydrogenase
42
Which molecule accepts hydrogen in the pentose phosphate pathway?
Απάντηση
(B)
NADP
43
Where are the enzymes of the pentose phosphate pathway located?
Απάντηση
(A)
Cytosol
44
What enzyme converts D-ribulose-5-phosphate to D-ribose-5-phosphate in the pentose phosphate pathway?
Απάντηση
(B)
Ketoisomerase
45
Which B vitamin is required by the transketolase enzyme in the pentose phosphate pathway?
Απάντηση
(B)
Thiamin
46
In a reaction, Xylulose-5-phosphate donates active glycolaldehyde. Which molecule acts as the acceptor?
Απάντηση
(A)
Erythrose 4-phosphate
47
What is a significant product generated by the pentose phosphate pathway?
Απάντηση
(A)
NADPH for reductive synthesis
48
The pentose phosphate pathway helps protect erythrocytes from hemolysis by supporting which enzyme?
Απάντηση
(C)
Glutathionic peroxidase
49
What enzyme deficiency in the pentose phosphate pathway is often associated with hemolytic anemia?
