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2.1 Biochemistry of Metabolism > Brenda - Glycolysis Regulation > Flashcards

Brenda - Glycolysis Regulation Flashcards

1
Q

What type of reaction is the conversion of pyruvate to acetyl-coA?

A

Oxidative decarboxylation, catalysed by PDH

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2
Q

Give two fates of acetyl CoA

A

Fatty acid synthesis

Converted to ketone bodies

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3
Q

What happens to pyruvate in yeast?
(2)

A

Pyruvate is converted to ethanol and CO2

This oxidises NADH to NAD+

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4
Q

How does bakers yeast work?
(2)

A

Yeast produces CO2 by pyruvate decarboxylation which causes bread to rise

Ethanol is also produced by it evaporates during baking

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5
Q

Where is lactate produced in mammals?

A

Skeletal muscles during exercise

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6
Q

What happens when lactate is formed?

A

It is transported out of muscle cells and brought to the liver where it is converted to pyruvate

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7
Q

When do all tissues produce lactate?

A

When O2 supply is inadequate all tissue produce lactate by anaerobic glycolysis

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8
Q

What is lactate acidosis?

A

The accumulation of lactate and elevation of lactic acid in the blood

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9
Q

How does glucose move into cells?
(3)

A

Moves by passive transport
Glucose conc in cells «< blood glucose
Moves through membrane-spanning glucose transporters

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10
Q

What happens to glucose inside the cell?

A

Glucose is phosphorylated

Phosphorylated glucose cannot cross plasma membrane

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11
Q

Write a note on the regulation of hexokinase
(4)

A

G6P inhibits Hexokinase isozymes I, II, III

G6P levels up when glycolysis is inhibited

Glucokinase is not inhibited by G6P

Liver cells can form G6P by action of glucokinase when glucose is abundant

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12
Q

List the three major control sites for glycolysis
(enzymes)

A

Phosphofructokinase

Pyruvate kinase

Hexokinase

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13
Q

What inhibits phosphofructokinase?
(3)

A

ATP

Citrate

H+

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14
Q

How does ATP inhibit phosphofructokinase?

A

ATP lowers enzyme affinity for fructose-6-phosophate

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15
Q

How does citrate inhibit phosphofructokinase?

A

Citrate works by enhancing the inhibitory effect of ATP

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16
Q

What reverses the inhibitory action of ATP?

A

Increased levels of ADP -> this increases PFK activity

17
Q

What activates phosphofructokinase?
(2)

A

AMP
F-2-6-bisP

18
Q

How does F-2-6-bisP activate PFK?

A

F-2,6-BisP activates PFK in the liver by increasing its affinity for F6P and decreasing the inhibitory effect of ATP

19
Q

What inhibits pyruvate kinase?
(2)

A

High ATP

Acetyl CoA

20
Q

How does high ATP inhibit pyruvate kinase?

A

High ATP reduces the affinity of pyruvate kinase for phosphoenolpyruvate

21
Q

What activates pyruvate kinase?

A

F 1,6-BisP

22
Q

How does F 1,6-BisP activate pyruvate kinase?

A

It allows pyruvate kinase to keep pace with the high flux of intermediates -> feedforward action

22
Q

How does F 1,6-BisP activate pyruvate kinase?

A

It allows pyruvate kinase to keep pace with the high flux of intermediates -> feedforward action

23
Q

How is pyruvate kinase inhibited by acetyl CoA?

A

Acetyl CoA is a major product of fatty acid oxidation i.e. energy from B oxidation has been made, we don’t need more energy

24
Q

How is pyruvate kinase inhibited by acetyl CoA?

A

Acetyl CoA is a major product of fatty acid oxidation i.e. energy from B oxidation has been made, we don’t need more energy

25
Q

What does glucagon regulate?
(2)

A

Glucagon regulates (PFK2) the enzyme which synthesises F2, 6BP

Glucagon regulates the enzyme (FBPase2) which hydrolyses F2,6BP back into F6P

26
Q

What does glucagon regulate?
(2)

A

Glucagon regulates (PFK2) the enzyme which synthesises F2, 6BP

Glucagon regulates the enzyme (FBPase2) which hydrolyses F2,6BP back into F6P

27
Q

What is the overall affect of glucagon?

A

It causes glycolysis to slow down when blood glucose falls

28
Q

PFK is inhibited by H+ ions, why is this important?

A

It prevents excessive formation of lactate under anaerobic conditions

29
Q

Explain how HK inhibition and PKF inhibition work together to turn off glycolysis
(2)

A

When PKF is inhibited large amounts of G6P build up

G6P then inhibits PKF -> preventing the first step of glycolysis

2.1 Biochemistry of Metabolism (21 decks)

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