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Meharry Biochem > Glycolysis > Flashcards

Glycolysis Flashcards

1
Q

Where do glycolysis take place

A

In cytosol

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2
Q

Does glycolysis require oxygen

A

No , can function either in the
presence of oxygen (aerobically) or in the
absence of oxygen (anaerobically)

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3
Q

What is the end product of glycolysis

A

Pyruvate

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4
Q

What are the 2 general functions of glycolysis

A

Provides ATP

Provides intermediate for other pathways

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5
Q

What role does glycolysis play in red blood cells

A

Exclusive source of energy because RBC lacks

mitochondria

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6
Q

What role does glycolysis play in skeletal muscles

A

Source of energy during exercise

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7
Q

What role does glycolysis play in liver and adipose tissue

A

Triglyceride (source of glycerol phosphate) and fatty acid (source of acetyl-CoA) synthesis

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8
Q

What is the enzyme that changes glucose into glucose 6 phosphate

A

Hexokinase

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9
Q

Can glucose exit the cell after get converted into g6p

A

No, Cells trap glucose by phosphorylating it,
preventing exit on glucose carriers
Glucose -6-P cannot diffuse through the membrane

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10
Q

What is the name of the isoenzyme of hexokinase . And which one has a higher affinity for glucose .

A

Glucokinase = Isoenzyme of hexokinase

Hexokinase has a higher affinity for glucose

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11
Q

In what cells do we find glucokinase

A

Liver, beta cells of pancreas

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12
Q

What 2 pathways glucokinase (isoenzyme of hexokinase)is used in

A

Provides glucose-6-P for glycogen synthesis and
lipogenesis [when glucose is in excess of
requirement for glycolysis]

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13
Q

What is the enzyme for the rate limiting step of glycolysis?

A

Phosphofructokinase (PFK)

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14
Q

What can occur if there is a deficiency in pfk ?

A

Deficiency of PFK-1 = increases insulin resistance and thus develops Ty p e 2 diabetes)

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15
Q

PFK creates what product

A

Fructose 1-6 Bis P

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16
Q

What is significant about step 6 of glycolysis

A

This is the only step in Glycolysis in which NAD+ is reduced to NADH

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17
Q

Glycolysis makes ATP via _________ phosphorylation

A

Substrate level phosphorylation

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18
Q

What is significant about step 7 in glycolysis

A

ATP created

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19
Q

What is significant about step 10 of glycolysis

A

ATP generated via substrate level phosphorylation

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20
Q

What enzyme is involved in step 10 of glycolysis

A

Pyruvate kinase

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21
Q

How many ATPs are invested in glycolysis

A

2

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22
Q

What inhibits hexokinase

A

The product ( Glucose 6 Phosphate)

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23
Q

How many NADH and ATP are generated in the payoff phase of glycolysis

A

2 NADH, 4 ATP

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24
Q

What is the net gain of ATP per molecule of glucose in glycolysis

A

2 molecules of ATP per molecule of glucose

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25
Q

How many NADH are produced in glycolysis

A

2

26
Q

First site of ATP formation (Reaction 7) may be bypassed in _______

A

First site of ATP formation (Reaction 7) may be bypassed in RBC

27
Q

Name the enzyme for the bypass route for reaction 7 , under what circumstances does this occur?

A

Bisphosphoglycerate mutase catalyzes
• 1,3-bisphosphoglycerate —> 2,3bisphosphoglycerate

This occurs is red blood cells

28
Q

What are the bypass results from reaction 7 of glycolysis

A

No net yield of AT P from glycolysis
2,3-bisphosphoglycerate binds to hemoglobin
Thus decreasing the affinity of hemoglobin to bind
oxygen
Making oxygen more readily available to tissues

29
Q

What is significant about 2-3 bisphosphoglycerate

A

It is the product in step 7 of glycolysis that occurs in Red blood cells. This product binds to hemoglobin , so that it cant bind to oxygen. This makes oxygen more readily available in the the tissues

30
Q

How many regulatory steps are there in glycolysis

A

3

31
Q

What are the 3 enzymes involved in the regulatory steps of glycolysis

A
  1. Hexokinase
  2. Phosphofructokinase
  3. Pyruvate Kinase
32
Q

Hexonkinase is _______ by glucose 6 phosphate

A

Inhibited

33
Q

The inhibition of hexokinase is known as _____ inhibition

A

Product inhibition

34
Q

Phosphofructokinase is the ____ step of glycolysis

A

Rate limiting

35
Q

List the 2 inducible enzymes for PFK

A

Inducible enzyme:

  • Induced in feeding by insulin
  • Repressed in starvation by glucagon
36
Q

Name 2 types of allosteric regulation that inhibit PFK

A

Citrate, ATP

37
Q

In terms of allosteric regulation list to enzymes that activate PFK

A

Fructose 2-6 bisphosphate Bis P, AMP

38
Q

The production of which molecule will be directly affected in someone with type 1 diabetes

A

Fructose 1-6 BP

39
Q

Would PFK be activated during a MI?

A

During a myocardial infarction, the oxygen supply to an
area of the heart is dramatically reduced. Under these
anaerobic conditions, phosphofructokinase would be
activated by increased levels of intracellular AMP

40
Q

The fate of pyruvate depends on what

A

It depends on the redox state of the tissue, ( if o2 is available or not)

41
Q

What happens to pyruvate under anaerobic conditions

A

Anaerobic condition (e.g. in exercising muscle,
RBC)
•Formation of lactate by lactate dehydrogenase

42
Q

What is the fate of pyruvate during aerobic conditions

A

Aerobic condition

•Enters mitochondria •Formation of acetyl coA via citric acid cycle

43
Q

Is lactate formed under aerobic or anaerobic conditions

A

Anaerobic

44
Q

Is acetal coa formed under aerobic or anaerobic conditions

A

Aerobic

45
Q

The transformation of pyruvate to lactate is an oxidation or reduction reaction

A

Reduction

46
Q

What is the name of the enzyme involved in pyruvate going to lactate I

A

Lacatate Dehydrogenase

47
Q

____ is derived from the vitamin Niacin

A

NAD+

48
Q

What structure does pyruvate enter

A

Mitochondria

49
Q

What occurs in the PDC

A

Oxidative decarboxylation of pyruvate produces acetyl-CoA by

pyruvate dehydrogenase enzyme complex

50
Q

What is the name of the substrate the enters the citric acid cycle

A

Acetyl coa

51
Q

Are any ATP produced in the conversion of pyruvate to acytal coa

A

No!

52
Q

What is produced during the conversion of pyruvate to acetal coa

A

NADH

53
Q

How many enzymes are found in the PDC

A

It’s a MULTI ENZYME complex, so it has 3

54
Q

List 3 advantages of having a multi enzyme complex

A
  1. Higher rate of reaction
  2. Minimum side reaction
  3. Coordinated control
55
Q

Is acytal coa an inhibitor or activator of PFK?

A

Inhibitor !

56
Q

How many molecules of oxygen (O 2) are required to complete the
reactions of aerobic respiration beginning with four molecules of glucose?

A

Glucose = C6H1206

We have 6 oxygens x 4 molecules = 24

57
Q

Impaired pyruvate metabolism can lead to

A

Lactic acidosis

58
Q

Lack of pyruvate kinase can lead to

A

Hemolytic anemia

59
Q

What does high AMP signal

A

Low energy , need ATP generation

60
Q

High levels of ATP and citrate

A

Glycolysis inhibited

Meharry Biochem (17 decks)

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