Glycolysis

Question 1

What is the function of the glycolytic pathway in terms of the metabolic release of energy?

Answer 1

the glycolytic pathway breaks down trapped glucose into 2 pyruvate molecules and releases energy
It also produces NADH which provides electrons later in cellular respiration

Question 2

Identify the key features of glycolysis

Answer 2

• utilises substrate level phosphorylation

- breaks down 1 molecule of glucose (6 carbon) into 2 molecules of pyruvate (3 carbon)

Question 3

What factors effect how pyruvate is used/produced?

Answer 3

• the oxygen levels present within the body

Question 4

What is the metabolic importance of regenerating NAD+?

Answer 4

NAD+ is required to continue glycolysis from the beginning again, without it’s production energy cannot be produced

Question 5

When and why might anaerobic glycolysis be important?

Answer 5

• during strenuous exercise

- in red blood cells where there is no mitochondria

Question 6

What is the difference between the digestion and mobilisation of sugars?

Answer 6

digestion refers to breaking down large molecules in food via mechanical processes such as chewing

mobilisation refers to breaking down already stored molecules such as glycogen

Question 7

Why is glycogenolysis important?

Answer 7

This process is important when gaining glucose from other sources or when it is not available

Question 8

What occurs in step 2?

Answer 8

conversion of glucose-6-phosphate to fructose-6-phosphate

Question 9

What occurs in step 3?

Answer 9

phosphorylation of fructose-6-phosphate into fructose -1,6- biphosphate

Question 10

What occurs in step 4?

Answer 10

fructose 1,6 biphosphate is cleaved

Question 11

What occurs in step 5?

Answer 11

DHAP is converted into glyceraldehyde-3-phosphate

Question 12

What occurs in step 6?

Answer 12

glyceraldehyde 3- phosphate is oxidised to 1,3-biphosphoglycerate

Question 13

What occurs in step 7?

Answer 13

phosphoryl transfer from 1,3-biphosphoglycerate to 3-phosphoglycerate

ATP is formed

Question 14

What occurs in step 8?

Answer 14

3- phosphoglycerate becomes 2-

Question 15

What occurs in step 9?

Answer 15

2-phosphoglycerate is dehydrated

Question 16

What occurs in step 10?

Answer 16

a phosphoryl group is transferred

ATP is formed

Question 17

What happens to pyruvate under aerobic conditions?

Answer 17

• pyruvate is oxidised to acetyl-coA (oxidative decraboxylation)
• Five coenzymes are involved in this five step reaction
• NAD+ is reduced to NADH producing 5 ATP (2 pyruvate = 2x 2.5 )

Question 18

What happens to pyruvate under anaerobic conditions?

Answer 18

• pyruvate is reduced to lactate in animals via lactate dehydrogenase

Question 19

Which cells may always undergo anaerobic respiration

Answer 19

• Red blood cells

as they do not have mitochondria

Question 20

How does glucose get produced from our diet?

Answer 20

• polymers in our food (beginning in the salivary glands) are hydrolysed into glucose

Question 21

How does glycogen get broken into glucose?

Answer 21

• glycogen stores are our main glucose storage

- it is hydrolysed into subunits

Question 22

What occurs to glycogen stored in the liver?

Answer 22

• glycogen is hydrolysisd to glucose by the enzyme glucose 6 phosphate which only exists in the liver
• this helps to maintain blood glucose levels

Question 23

What occurs to glycogen stored in the muscle?

Answer 23

• Glucose 6 phosphate directly enters glycolysis

- this acts as energy for muscle contraction