MODULE 2 Flashcards

0
Q

Catalysis occurs at the _________ of the enzyme.

A

Active site

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1
Q

Physically distinct versions of enzymes that catalyze the same reaction.

A

Isoenzymes

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2
Q

With tight and stable attachment to the enzyme.

A

Prosthetic groups

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3
Q

With transient, dissociable attachment to the enzyme.

A

Cofactors

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4
Q

Serves as substrate shuttles.

A

Coenzymes

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5
Q

Is the joining of small biochemical to form larger molecules.

A

Anabolism

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6
Q

Involves both anabolic and catabolic pathways.

A

Amphibolic pathways

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7
Q

Fatty acids are esterified to form __________.

A

Triacylglycerol

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8
Q

Acetyl CoA is oxidized to CO2 and H2O via this cyle.

A

Citric acid cycle

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9
Q

A metabolic pathway by which a 6-carbon glucose molecule is oxidized to two molecules of a 3-carbon sugar called pyruvate in the presence of oxygen.

A

Glycolysis

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10
Q

Glycolysis takes place within the _________ of the cell.

A

Cytosol

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11
Q

It is also referred to as the EmbdenMeyerhof pathway.

A

Glycolysis

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12
Q

Fructose-6-phosphate is converted to Fructose-1,6-biphosphate via which enzyme.

A. Hexokinase
B. Aldolase
C. PFK-1
D. Phosphohexose isomerase

A

C. PFK-1

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13
Q

It is an enzyme that catalyzes the transfer of a phosphoryl group from ATP to a substrate.

A

Kinase

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14
Q

Type IV isoenzyme of hexokinase.

A

Glucokinase

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15
Q

The following are true for the enzyme hexokinase EXCEPT:

A. Found in most tissues
B. Inhibited by glucose 6-P
C. O.1 mM Km for glucose
D. High in liver

A

D. High in liver

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16
Q

After meals, when prostpandial blood glucose are high, liver _________ is significantly active.

A

Glucokinase

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17
Q

Hexokinase requires _______ ion for its activity.

A

Magnesium

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18
Q

After step 2 of glycolysis, which carbon is no longer part of the ring structure?

A

C1

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19
Q

This is considered as the rate limiting enzyme of glycolysis.

A

Phosphofructokinase

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20
Q

Dihydroxyacetone phosphate is converetd to glyceraldehyde-3-phosphate via what enzyme?

A

Triosephosphate isomerase

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21
Q

Enolase is inhibited by __________.

A

Flouride

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22
Q

The enol form of pyruvate undergoes this process to become a more stable pyruvate in keto form.

A

Tautomerization

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23
Q

The branch point molecule of glycolysis.

A

Pyruvate

24
Q

Pyruvate may also undergo carboxylation to _______ to provide a substrate for gluconeogenesis.

A

Oxaloacetate

25
Q

The pyruvate dehydrogenase complex consists of 3 enzymes:

A
Pyruvate dehydrogenase (E1)
Dihydrolipoyl transacetylase (E2)
Dihydrolipoly dehydrogenase (E3)
26
Q

The 2-carbon hydroxyethyl group after oxidation of pyruvate binds to..

A

Thiamine pyrophosphate (TPP)

27
Q

The following inhibits PFK EXCEPT:

A. Citrate
B. AMP
C. ATP
D. Glucagon

A

B. AMP

28
Q

The major energy-producing pathway in the body.

A

TCA or Kreb’s cycle

29
Q

TCA occurs in what part of the cell.

A

Mitochondrial matrix

30
Q

Acetyl CoA codenses with oxaloacetate to form citrate via which enzyme..

A

Citrate synthase

31
Q

An enzyme that makes a new covalent bond during a rxn without the involvement of an ATP molecule.

A

Synthase

32
Q

Two products of the hyrdolysis of the thioester bond in citrate synthase catalysis.

A

Coenzyme A-SH and citrate

33
Q

Aconitase catalyzes isomerization of citrate to __________.

A

Isocitrate

34
Q

The first oxidative decarboxylation reaction in the TCA cycle.

A

Oxidation of Isocitrate to alpha-ketoglutarate.

35
Q

Isocitrate dehydrogenase is allosterically activated by ________ and inhibited by ________.

A

ADP, NADH

36
Q

The alpha-ketoglutarate is converted to succinyl coenzyme A is considered the ______________ of TCA cycle.

A

Second oxidative decarboxylation reaction

37
Q

Succinyl CoA is cleaved to succinate via the action of…

A

Succinyl CoA synthetase

38
Q

Succinate dehydrogenase catalyzes which step in the TCA cycle.

A

Succinate to fumarate

39
Q

The only enzyme in TCA cycle found in the inner mitochondrial membrane.

A

Succinate dehydrogenase

40
Q

Water adds across the double bond of fumarate to form _________.

A

Malate

41
Q

Products of the TCA cycle.

A

2 CO2, 3 NADH, 1 FADH2, 1 GTP

42
Q

When ATP levels are high, the following occurs EXCEPT:

A. NADH allosterically inhibits isocitrate dehydrogenase.

B. Citrate inhibits citrate synthase.

C. Oxaloacetate is concerted to malate.

D. Isocitrate accumulates and favors the accumulation of citrate.

A

C. Oxaloacetate is concerted to malate.

43
Q

The following enzymes use NAD EXCEPT:

A. Succinate dehydrogenase
B. Isocitrate dehydrogenase
C. Malate dehydrogenase
D. Alpha-ketoglutarate dehydrogenase

A

A. Succinate dehydrogenase

44
Q

TRUE or FALSE: Citric acid cycle is amphibolic.

A

TRUE

45
Q

This the most important anaplerotic rxn:

Pyruvate + ATP + CO2 + H20 ➡️ Oxaloacetate + ADP + Pi

This rxn is catalzyed by __________ and its allosteric activator is __________.

A

Pyruvate carboxylase, Acetyl CoA

46
Q

Primary source of ATP in aerobic organism.

A

Oxidative phosphorylation

47
Q

ETC located in which specific part of the cell?

A

Inner mitochondrial membrane

48
Q

Mutations in complex II of the ETC.

A

Kearns-Sayre Syndrome

49
Q

What are the 3 irreversible and regulated steps in glycolysis?

A

Step 1: Phosphorylation of glucose
Step 3: Phosphorylation of fructose-6-phosphate
Step 10: Formation of pyruvate

50
Q

What is the substrate for gluconeogenesis?

A

Pyruvate

51
Q

90% of gluconeoegenesis occurs in the liver while 10% occurs in the..

A

Kidney

52
Q

Rate limiting step of gluconeogenesis.

A

Fructose 1,6 biphosphate ➡️ Fructose 6 phosphate via the enzyme fructose 1,6 biphosphatase

53
Q

Energy expense of the Cori cycle.

A

4 ATP molecules

54
Q

Glycogenesis occurs int he following EXCEPT:

A. Liver
B. Muscle
C. Cytosol
D. Kidneys

A

D. Kidneys

55
Q

Rate-limiting enzyme of glycogenesis

A

Glycogen synthase

56
Q

Activated form of glucose.

A

UDP-glucose

57
Q

Catecholamine that increases glycogenolysis in liver and muscles.

A

Epinephrine