FINAL EXAM CHAPTER 16 Glycolysis Flashcards

1
Q

Why is glucose such a prominent fuel molecule?

A
  1. Glucose may have been available for primitive biochemical systems because it can form under prebiotic conditions.
  2. Glucose is the most stable hexose
  3. Glucose has a low tendency to nonenzymatically glycosylate proteins
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2
Q

What are the start and end products of Glycolysis and how much ATP is extracted?

A

Converts one molecule of glucose to two molecules of pyruvate and generates two molecules of ATP

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3
Q

What happens in stage 1 of Glycolysis?

A

Stage 1 traps glucose in the cell and modifies it so that it can be cleaved into a pair of phosphorylated 3-carbon compounds

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4
Q

What happens in stage 2 of Glycolysis ?

A

Stage 2 oxidizes the 3-carbon compounds to pyruvate while generating two molecules of ATP

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5
Q

In stage 1, what does the enzyme Hexokinase catalyze? and is this favorable or unfavorable?

A

Glucose is phosphorylated at the expense of ATP to form glucose 6-phosphate
FAVORABLE

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6
Q

In stage 1,what does the enzyme phosphoglucose isomerase catalyze? And is this favorable or unfavorable?

A

Conversion of glucose 6-phosphate to fructose 6-phosphate.
NOT FAVORABLE

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7
Q

In stage 1, what does the enzyme Phosphofructokinase catalyze? And is this favorable or unfavorable?

A

Carbohydrate is trapped in the fructose form by the addition of a second phosphate to form fructose 1,6-Biphosphate
FAVORABLE

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8
Q

In stage 1, what does the enzyme Aldolase catalyze? And is this favorable or unfavorable?

A

It catalyzes the conversion of fructose 1-6-diphosphate to glyceraldehyde 3-phosphate(GAP) and Dihydroxyacetone phosphate(DHAP)
NOT FAVORABLE

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9
Q

In stage 1, what does the enzyme Triose Phosphate Isomerase catalyze? And is this favorable or unfavorable?

A

The conversion of Dihydroxyacetone phosphate (DHAP) to glyceraldehyde 3-phosphate(GAP).
NOT FAVORABLE

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10
Q

In the beginning of Stage 2, the oxidation of an Aldehyde powers the formation of which compound with High phosphoryl transfer potential?

A

1,3-Biphosphoglycerate

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11
Q

In stage 2, what does the enzyme glyceraldehyde 3-phosphate dehydrogenase catalyze? And is this favorable or unfavorable?

A

The oxidation of GAP which produces 1,3-Biphosphoglycerate
NOTE here NAD+ is consumed and it has to be regenerated if glycolysis is to continue
NOT FAVORABLE

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12
Q

IN the formation of 1,3-BIphosphoglycerate, what are the two steps that occur and why is an energy rich thioester required?

A
  1. Highly exergonic oxidation of carbon 1 in GAP
  2. Highly Endergonic formation of 1,3-Biphosphoglycerate from the acid

Energy rich thioester is required because the transition state free energy change is too large, and this will help reduce it

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13
Q

In the second step of stage 2, which molecule has a higher phosphate transfer potential; than ATP and what does the enzyme phosphoglycerate kinase catalyze? And is this favorable or unfavorable?

A

-1,3-Biphosphoglycerate has higher potential so it transfers the phosphate to ADP to generate ATP and the enzyme catalyzes this reaction
FAVORABLE

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14
Q

In stage 2, what does the enzyme Phosphoglycerate mutase catalyze? And is this favorable or unfavorable?

A

Conversion of 3-Phosphoglycerate into 2-phosphoglycerate
NOT FAVORABLE

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15
Q

In stage 2, what does the enzyme Enolase catalyze? And is this favorable or unfavorable?

A

a dehydration reaction that results in the production of Phosphoenolpyruvate from 2-Phosphoglycerate
NOT FAVORABLE

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16
Q

In stage 2, what does the enzyme Pyruvate Kinase catalyze? And is this favorable or unfavorable?

A

the phosphorylation of ADP at the expense of PEP, and this generates ATP and pyruvate.

WE are able to do the phosphorylation because PEP is a high phosphoryl transfer compound.
FAVORABLE

17
Q

How and why do we have to regenerate NAD+?

A

Because we need NAD+ for ATP synthesis.
This can be done by either further oxidation of pyruvate to CO2 or by the formation of ethanol or lactate from pyruvate.

18
Q

What is the reason for each of the molecular rearrangements?

A
19
Q

why might cancer cells slow glycolysis?

A

Because cancer cells express an isoform of PK called PKM2 that is less active than the normal isoform PKM1 and it causes build ups.