Glycolysis

Question 1

What are the 3 main stages of Glycolysis

Answer 1

1. Phosphorylation of glucose to hexose bisphosphate
2. Splitting of each hexose bisphosphate molecule into 2 triose phosphate molecules, each with a Pi attached
3. Oxidation of triose phosphate to pyruvate

Question 2

What is NAD?

Answer 2

• Non protein hydrogen carrying molecule
• Helps dehydrogenase enzymes carry out oxidation reactions
• Synthesised in living cells from nicotinamide (vitamin B3).
• Nicotinamide ring can accept 2 hydrogen atoms becoming reduced NAD

Question 3

What does Reduced NAD do?

Answer 3

Carries Hydrogens and electrons to cristae of mitochondria for oxidative phosphorylation which generates ATP from ADP and Pi

When NAD gives these hydrogens and electrons that it accepted during one of the first 3 stages, it becomes oxidised again and can be reused to oxidise more substrates, becoming reduced again, etc.

Question 4

How does phosphorylation of glucose actually work?

Answer 4

2 molecules of ATP are hydrolysed and the phosphoryl groups are added to the hexose ring to form hexose bisphosphate. The energy from the hydrolysed ATP molecules activates the hexose sugar preventing it from leaving the cell.

Question 5

How does the phosphorylation of triose phosphate to pyruvate actually work?

Answer 5

• Dehydrogenase enzymes remove H atoms from TP
• 2 NAD molecules accept h atoms becoming reduced
• 2 molecules of NAD reduced for every glucose molecule. 4 molecules of ATP for every 2 TP molecules

Question 6

What are the products of Glycolysis?

Answer 6

• 2 Molecules of ATP
• 2 Molecules of reduced NAD
• 2 molecules of pyruvate

Question 7

What happens after Glycolysis?

Answer 7

Link reaction, then Kreb’s Cycle, then Oxidative Phosphorylation