Glycolysis

Question 1

How is glucose broken down?

Answer 1

Glycolysis (catabolism)

Question 2

How is glucose reformed?

Answer 2

Gluconeogenesis (anabolism)

Question 3

Why does glycolysis happen so frequently?

Answer 3

A significant amount of glucose synthesis required to meet the brains requirements

Question 4

How do catabolism and anabolism occur temporally?

Answer 4

Catabolism and anabolism frequently occur at the same time however they are often spatially separated (cell and tissue)

Question 5

What is glycogen?

Answer 5

How we store glucose in the body

• Highly branched glucose polymer
• Stored as granules in the cytosol of cells
• Synthesis and breakdown is regulated by glucagon and insulin through protein phospholylation cascades

Question 6

Where are there high concentrations of glycogen?

Answer 6

Liver and muscles

• Liver glycogen is easily released into the circulation
• Muscle glycogen is for local use during exercise and fasting

Question 7

How many ATP molecules does one glucose molecule produce?

Answer 7

28-32

Question 8

What are the 4 steps of glycolysis?

Answer 8

1. Glucose (6C) is phosphorylated into glucose-6-phophate and then fructose-1,6-bisphosphate (6C) with the addition of 2 ATP molecules (Hexokinase)
2. fructose-1,6-bisphosphate (6C) splits into 2 molecules of glyceraldehyde-3-P (3C)
3. each glyceraldehyde-3-P (3C) is phosphorylated into a molecule of 1,3-Bisphosphoglycerate (3C)
4. Each molecule of 1,3-Bisphosphoglycerate (3C) loses a molecule of H to NAD to generate 2 NADH molecules and loses 2 phosphate groups to generate 4 ATP molecules. Each molecule of 1,3-Bisphosphoglycerate (3C) becomes a molecule of pyruvate (3C)

Question 9

How many ATP are used in glycolysis?

Answer 9

2

Question 10

How many ATP are made in glycolysis?

Answer 10

4

Question 11

What is the net production of ATP from glycolysis?

Answer 11

2

Question 12

How many NADH are generated in glycolysis?

Answer 12

2

Question 13

What does glycolysis need an input of?

Answer 13

ADP and NAD+

Question 14

Can other carbohydrates enter glycolysis?

Answer 14

Enter glycolysis at different points or are converted into glucose first

Question 15

What can happen to pyruvate once it is generated?

Answer 15

• Transaminated to alanine for gluconeogenesis
• Anaerobic respiration (fermentation) to make lactate
• In aerobic conditions it goes into the mitochondrial krebs cycle

Question 16

What is the process of glucose uptake?

Answer 16

• The only mechanism by which cells can take up glucose is by facillitated diffusion through a family of hexose transporters. In many tissues - muscles for example - the major transporter used for the uptake of glucose (GLUT4) is made available in the plasma membrane through the action of insulin

Question 17

What happens to pyruvate in the link reaction?

Answer 17

Pyruvate combines with Co-A to form Acetyl-CoA and CO2 reducing a molecule of NAD to NADH
- Pyruvate dehydrogenase complex

Question 18

What happens to pyruvate in anaerobic conditions?

Answer 18

Becomes lactate with addition of H from NADH

• Lactate dehydrogenase
• Lactate acidosis >5mM