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Biocheem > Lecture 32 > Flashcards

Lecture 32 Flashcards

1
Q

What does Hexokinase catylyze?

A

Glucose to Glucose-6-Phosphate

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2
Q

What inhibits hexokinase?

A

Glucose-6-Phosphate

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3
Q

How does Glucose-6-Phosphate affect Hexokinase?

A

It inhibits hexokinase

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4
Q

How what is G6P to Hexokinase?

A

It is a negative allosteric effector

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5
Q

What does G6P inhibiting hexokinase do?

A

It reduces the rate that glucose is converted to G6P

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6
Q

What kind of regulation is it for G6P to inhibit hexokinase?

A

Product inhibition

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7
Q

What does PFK-1 catalyze?

A

The conversion of Fructose-6-P to Fructose-1,6-BP

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8
Q

What is PFK-1 allosterically regulated by?

A

ADP/AMP and PEP

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9
Q

What kind of inhibition is PEP regulating PFK-1?

A

Feedback inhibition

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10
Q

What is a good indicator of the need for ATP in a cell?

A

ADP/AMP concentrations

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11
Q

When do ADP and AMP concentrations increase?

A

When a cell is consuming ATP

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12
Q

What is ADP and AMP to PFK-1?

A

A positive heteroallosteric effector of PFK-1

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13
Q

What is ATP to PFK-1?

A

An inhibitor of PFK-1

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14
Q

What is PFK-1 sensitive to?

A

The energy needs of the cell

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15
Q

Why is ATP complex with it regulation of PFK-1?

A

Because it is also a substrate of PFK-1

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16
Q

What is ATP to PFK-1?

A

It is a homoallosteric inhibitor (which is rare). This is because it is a substrate but it is also a product

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17
Q

What does Pyruvate kinase catalyse?

A

The conversion of phosphoenolpyruvate to Pyruvate

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18
Q

What would happen if pyruvate kinase is inhibited?

A

The levels of phosphoenolpyruvate will increase which then inhibits PFK-1

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19
Q

What does elevated PEP signal?

A

The products of glycolysis are not being consumed

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20
Q

What is F-6-P for PFK-1?

A

A positive homoallosteric effector because it is a substrate and an activator?

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21
Q

How would increasing concentration of F-6-P affect the rate vs concentration graph?

A

It will shift toward the r state

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22
Q

What does a sigmoidal shape on a rxn velocity vs substrate graph mean?

A

The substrate is also an activator

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23
Q

What happens if AMP is added to a PFK-1 rate vs conc of F-6-P graph?

A

Because AMP is a positive heteroallosteric effector, it will shift the curve to the left because it increases the activity of PFK-1

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24
Q

How does PEP affect the graph of rate PFK-1 to F-6-P conc?

A

It will shift the curve to the right because PEP is a negative hetero allosteric effector of PFK-1

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25
Q

What is Pyruvate Kinase affected by?

A

ATP and Fructose-1,6-bisphosphate

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26
Q

What does Pyruvate Kinase catalyze?

A

PEP to Pyruvate

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27
Q

What is Pyruvate kinase inhibited by?

A

ATP

28
Q

What is Pyruvate Kinase activated by?

A

Fructorse-1,6-bisphosphate

29
Q

What kind of inhibition is ATP to Pyruvate kinase?

A

Product inhibition

30
Q

What does PFK-1 produce when activity is high?

A

Fructose-1,6-bisphosphate as a product

31
Q

Where does Fructose-1,6-bisphosphate act as an activator for Pyruvate?

A

In yeast

32
Q

What kind of activation if F-1,6-bisphosphate to pyruvate?

A

Feedforward activation

33
Q

What is ATP to Pyruvate Kinase?

A

An allosteric inhibitor, through product inhibition

34
Q

What kind of relationship is seen on the graph of Pyruvate Kinase vs conc of PEP and what does it indicate?

A

There is a sigmoidal relationship indicating that PEP is a substrate and a homoallosteric activator

35
Q

How does F1,6BP affect the pyruvate kinase vs PEP conc graph and why?

A

It shifts the graph to the left because PEP is a positive heteroallosteric activator

36
Q

How does ATP affect the pyruvate kinase vs PEP conc graph and why?

A

It shifts the graph to the right because ATP is a negative hetero allosteric effector of pyruvate kinase

37
Q

Which enzymes in glycolysis are affected by ATP?

A

PFK-1 and PK. They are both inhibited

38
Q

Which reactions in glycolysis consume ATP?

A
  • Conversion of glucose to glucose-6-phosphate

* Conversion of F-6-P to F-1,6-bisphosphate

39
Q

Which enzymes are regulated in glycolysis?

A
  • Hexokinase
  • Pyruvate kinase
  • Phosphofructokinase
40
Q

Which enzyme do you need to know that is not regulated in glycolysis?

A

GAPDH

41
Q

What are the high energy molecules in glycolysis?

A

ATP, NADH, 1,3-BPG and Phosphoenolpyruvate

42
Q

What are the high energy products of glycolysis?

A

ATP and NADH

43
Q

What are the high energy intermediates in glycolysis?

A

1,3-BPG and PEP

44
Q

What is Glycogen synthesized from?

A

Glucose-6-phosphate (anabolic)

45
Q

What does the breakdown glycogen use?

A

Inorganic phosphate to break glycosidic bonds

46
Q

What can glycogen be broken down into/

A

Less glycogen and glucose-1-phosphate

47
Q

What is used to the reaction to breakdown Glycogen?

A

Pi

48
Q

What happens Glucose-1-phosphate from the breakdown of glycogen?

A

It is converted to Glucose-6-phosphate which is an isomer

49
Q

How much ATP is used to generate G-6-P from glycogen?

A

No ATP

50
Q

How does Glycogen metabolism affect NET yield of ATP?

A

It increases net yield of ATP by 1 so instead of 2 ATP, 3 ATP is produced

51
Q

What is generated at the end of glycolysis?

A

Pyruvate

52
Q

What is the fate of Pyruvate aerobically?

A

It can be converted to acetyl CoA by oxidative phosphorylation

53
Q

What is the fate of Pyruvate anaerobically?

A

It can be converted to Lactate or Ethanol

54
Q

What is the difference between pyruvate and alanine?

A

Pyruvate contains a carbonyl where alanine contains an amino

55
Q

What high energy molecules are made during glycolysis?

A

ATP and NADH

56
Q

What can happen to NADH under aerobic conditions?

A

It can be oxidized to NAD+

57
Q

What can happen to NADH under anaerobic conditions?

A

NADH will begin to accumulate because there is no oxygen to oxidize it

58
Q

What can happen if NADH accumulates due to anaerobic conditons?

A

Raising the level of products from glycolysis will stop the reaction from proceeding

59
Q

How many NADH is made for every pyruvate in glycolysis?

A

1 NADH is made for every pyruvate

60
Q

What can convert the NADH back into NAD+ aside from O2?

A

Glucose

61
Q

How many NADH, pyruvate and ATP are produced at the end of glycolysis?

A
  • 2 Pyruvate
  • 2 NADH
  • 2 Net ATP
62
Q

What needs to happen to NADH for glycolysis to continue?

A

It need to be reoxidized to NAD+

63
Q

What can help convert NADH to NAD+ in at the end of gylcolysis?

A
  • Oxidative phosphorylation - anaerobic

* Pyruvate reduction (anaerobic)

64
Q

What are the two ways of Pyruvate oxidation to convert NADH back to NAD+ anerobic?

A
  • Ethanol (yeast)

* Lactate formation in muscle/RBCs

65
Q

What does the reaction of Pyruvate NADH and an H+ produce?

A

L-lactate and NAD+

66
Q

What does Lactate Dehydrogenase do?

A

Catalyzes the conversion of pyruvate to lactate and the oxidation of NADH for glycolysis to continue

67
Q

What is the reduced form of pyruvate?

A

Lactate

Biocheem (38 decks)

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