Carbohydrates 3 Flashcards

1
Q

What is glycolysis?

A

Biochemical reaction, not involving oxygen, that splits carbohydrates into pyruvic or lactic acid whilst producing ATP

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2
Q

What kind of phosphorylation does glyclysis produce ATP through?

A

Substrate level phosphorylation

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3
Q

What is the only way that energy can be made when O2 is not present?

A

Substrate level phosphorylation

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4
Q

Why is glycolysis often the process used to generate energy initially during exercise?

A

O2 cannot get to the cells quick enough

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5
Q

What are the 2 phases of glycolysis?

A

Preparation phase

Payoff phase

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6
Q

What happens during the preparative phase of glycolysis?

A

Two molecules of glucose-3-phosphate are produced per molecule of glucose

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7
Q

What happens during the payoff phase of glycolysis?

A

ATP is produced

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8
Q

What is the net gain of ATP in glycolysis and how is this distributed between the preparative and payoff phases?

A

2 ATP is used during the preparative phase and 4 ATP is gained during the payoff phase

Net gain of 2 ATP per molecule of glucose

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9
Q

How many steps are there in glycolysis?

A

10

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10
Q

How many of the 10 glycolysis steps are irreversible?

A

3

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11
Q

Why are the irreversible steps of glycolysis irreversible?

A

Delta G during those reactions is to highly negative, too much energy put be required to reverse the reaction

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12
Q

What are the 10 steps of glycolysis?

A
  1. Phosphorylation of glucose (glucose → glucose-6-phosphate)
  2. Conversion of G-6-P to F-6-P
  3. Phosphorylation of F-6-P to F-1,6-bisP
  4. Cleavege to F-1,6-bisP
  5. Interconversion of triose sugars
  6. Oxidation of glyceraldehyde-3-phosphate (G-3-P) to 1,3-bisphosphoglycerate (1,3-bisPG)
  7. P transfer from 1,3-bisPG to ADP
  8. Conversion of 3-PG to 2-PG
  9. Dehydrogenase of 2-PG to phosphoenolpyruvate (PEP)
  10. Transfer of P from PEP to ADP, producing pyruvate
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13
Q

What is fructose-1,6-bisP broken down to into step 4 of glycolysis?

A

Glyceraldehyde-3-P or dihydroxyacetone-P

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14
Q

What are the 3 irreversible steps of glycolysis?

A

Step 1 - Phosphorylation of glucose (glucose → glucose-6-phosphate)

Step 3 - Phosphorylation of F-6-P to F-1,6-bisP

Step 10 - Transfer of P from PEP to ADP, producing pyruvate

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15
Q

Why is glucose converted to fructose in step 3?

A

This lowers the activation energy to proceed due to the negative charges of fructose repelling each other

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16
Q

What is the first commited step of glycolysis?

A

Phosphorylation of F-6-P to F-1,6-bisP because previous intermediates can be used for other pathways but F-1,6bisP is destined for glycolysis

17
Q

What is a difference in the requirments of substrate level phosphorylation compared to oxidative phosphorylation, in terms of enzymes?

A

Substrate level phosphorylation requires soluble enzymes and chemical intermediates, whereas oxidative phosphorylation involves membrane bound enzymes and gradients of protons

18
Q

What does a diagram of glycolysis look like?

A
19
Q

Why does NAD+ need to be regenerated?

A

It is limited in the cell

20
Q

Where does NAD+ come from?

A

Niacin which is an essential vitamin

21
Q

What do all fates of pyruvate do?

A

Regenerate NAD+ to replinish what was used during glycolysis

22
Q

What is redox balance?

A

The replinishment of NAD+ after glycolysis

23
Q

What are the 3 pathways that pyruvate can take?

A

Fermentation in yeast to ethanol

Aerobic respiration to CO2

Fermentation in vigorously contracting muscle cells to lactate

24
Q

What does the reaction of yeast producing ethanol look like?

A
25
Q

How much pyruvate is produced per molecule of glucose?

A

2

26
Q

How much lactate can be produced per molecule of pyruvate?

A

1

27
Q

How much acetyl coenzyme A can be produced per molecule of pyruvate?

A

1

28
Q

What does pyruvate becoming in the absence of oxygen?

A

Lactate

29
Q

What does the reaction of pyruvate to lactate look like?

A
30
Q

What is the Cori cycle?

A

Metabolic pathway where lactate is produced by anaerobic glycolysis

31
Q

What happens if we exercise vigorously?

A

Muscles don’t recieve O2 fast enough to make ATP by oxidative phosphorylation, instead using substrate level phosphorylation producing lactate

32
Q

What is the fate of lactate that is produced from pyruvate?

A

Transfered to the liver and converted to glucose through gluconeogenisis

33
Q

Where does glycolysis happen?

A

In a cells cytoplasm

34
Q

What happens to pyruvate when cells have access to O2?

A

Oxidised to form acetyl coenzyme A

35
Q

Where does the reaction of pyruvate to acetyl coenzyme A take place?

A

In the mitochondria of cells

36
Q

Why can red blood cells only do glycolysis (substrate level phosphorylation)?

A

They do not have any mitochondria to do oxidative level phosphorylation

37
Q

What is also formed when pyruvate is converted into acetyl coenzyme A?

A

NADH which later gives up its hydride ion (H-) in the electron transport chain

38
Q

What does the reaction of pyruvate to acetyl conenzyme A look like?

A