Glycolysis

Question 1

Where does glycolysis occur ?

Answer 1

In the cytoplasm

Question 2

What is glycolysis ?

Answer 2

The conversion of glucose to pyruvate

Question 3

What are the 2 stages of glycolysis ?

Answer 3

1. Trapping destabilising glucose
2. Energy generation

Question 4

Describe stage 1 of glycolysis

Answer 4

1. Glucose is converted into Glucose 6-phosphate
2. Glucose 6-phosphate is converted into Fructose 6-phosphate
3. Fructose 6-phosphate is converted into Fructose 1,6-bisphosphate
4. Fructose 1,6-bisphosphate is converted into Glyceraldehyde 3-phosphate + Dihydroxyacetone phosphate (3C molecules)

Question 5

What enzyme catalyses the conversion of glucose to glucose 6-phosphate ?

Answer 5

Hexokinase

Question 6

What enzyme catalyses the conversion of glucose 6-phosphate to fructose 6-phosphate?

Answer 6

Phosphohexose isomerase

Question 7

What enzyme catalyses the conversion of fructose 6-phosphate to fructose 1,6-bisphosphate ?

Answer 7

Phosphofructokinase

Question 8

What enzyme catalyses the conversion of fructose 1,6-bisphosphate to Glyceraldehyde 3-phosphate + Dihydroxyacetone phosphate?

Answer 8

Aldolase

Question 9

What enzyme catalyses the conversion between Dihydroxyacetone phosphate and Glyceraldehyde 3-phosphate?

Answer 9

Triose phosphate isomerase

Question 10

Why is the reaction catalysed by hexokinase important?

Answer 10

It traps glucose inside the cell as glucose 6-phosphate is charged so cannot cross the cell membrane

Question 11

How many ATP molecules does stage 1 of glycolysis use ?

Answer 11

2 ATP molecules

Question 12

What are the steps of stage 2 glycolysis?

Answer 12

1. Glyceraldehyde 3-phosphate is converted into 1,3-Bisphosphoglycerate
2. 1,3-Bisphosphoglycerate is converted into 3-Phosphoglycerate
3. 3-Phosphoglycerate is converted into 2-Phosphoglycerate
4. 2-Phosphoglycerate is converted into Phosphoenolpyruvate
5. Phosphoenolpyruvate is converted into Pyruvate

Question 13

What enzyme catalyses the conversion of Glyceraldehyde 3-phosphate into 1,3-Bisphosphoglycerate ?

Answer 13

Glyceraldehyde 3-phosphate dehydrogenase
The dehydrogenase transfers ‘high energy’ electrons from NAD+ to form NADH

Question 14

What enzyme catalyses the conversion of 1,3-Bisphosphoglycerate into 3-Phophoglycerate ?

Answer 14

Phosphoglycerate kinase

Question 15

What enzyme catalyses the conversion of 3-Phosphoglycerate into 2-Phosphoglycerate ?

Answer 15

Phosphoglycerate mutase

Question 16

What enzyme catalyses the conversion of 2-Phosphoglycerate into Phosphoenolpyruvate ?

Answer 16

Enolase

Question 17

What enzyme catalyses the conversion of Phosphoenolpyruvate into Pyruvate ?

Answer 17

Pyruvate kinase

Question 18

How many ATPs are used in stage 2 of glycolysis ?

Answer 18

4 ATPs

Question 19

Describe the catabolic fates of pyruvate

Answer 19

1. Lactic acid fermentation
2. Ethanol formation
3. Formation of Acetyl-CoA

Question 20

Describe the conversion of pyruvate to Acetyl-CoA

Answer 20

The enzyme pyruvate dehydrogenase complex is used.
Acetyl-CoA enters the Krebs cycle to produce more NADH

Question 21

Describe lactic acid fermentation

Answer 21

The enzyme lactate dehydrogenase is used.
It regenerates NAD+ to allow glycolysis to continue.

Question 22

Describe ethanol formation from pyruvate

Answer 22

Pyruvate is converted into Acetaldehyde by the enzyme Pyruvate dehydrogenase.
Acetaldehyde is then converted into ethanol by the enzyme Alcohol dehydrogenase