Glycolysis

Question 1

What is glucose converted into? Describe this step

Answer 1

Glucose 6-phosphate
• Phosphorylation
• ATP is converted to ADP
• Traps the glucose in the cell because glucose 6 phosphate is ionised and can’t cross the membrane

Question 2

What is glucose 6 phosphate converted into? Describe this step

Answer 2

Fructose 6-phosphate
• Isomerisation
• Converted to a new sugar, both C6H12O2

Question 3

What is fructose 6-phosphate converted into? Describe this step

Answer 3

Fructose 1,6-bisphosphate
• Phosphorylation
• ATP converted to ADP
• Fructose 1,6-bisphosphate is a hexose diphosphate which can be split into 2 phosphorylated 3 carbon compounds

Question 4

What is Fructose 1,6-bisphosphate converted into? Describe this stage

Answer 4

• Glyceraldehyde and Dihroxyacetone phosphate (which is then broken down into another glceraldehyde molecule)

Question 5

What is Glyceraldehyde converted to? Describe this step

Answer 5

1,3 Bisphosphoglycerate
• oxidative phosphorylation
• Requires 1 phosphate per glyceraldehyde phosphate
• Requires one NAD+ per molecule, producing NADH

Question 6

What is 1,3 bisphophoglycerate converted into? Describe this step

Answer 6

3-phosphoglycerate
• Transfer of phosphate
• ADP converted to ATP per molecule

Question 7

What is 3-phosphoglycerate converted into? Describe this step

Answer 7

2-Phosphoglycerate
• Molecular rearrangement
• The phosphate group is moved

Question 8

What is 2-Phosphoglecerate converted into? Describe this step

Answer 8

Phosphoenol pyruvate
• Dehydration
• Gives a water molecule per molecule
• Favours the transport of the phosphate to ATP

Question 9

What is Phosphoenol pyruvate converted into? Describe this step

Answer 9

Pyruvate

• ADP converted to ATP per molecule

Question 10

What is the definition of glycolysis?

Answer 10

The breakdown of glucose into smaller molecules, producing ATP
(conversion of glucose to pyruvate)

Question 11

Where does glycolysis take place?

Answer 11

In the cytoplasm of the cells

Question 12

What makes up NAD+

Answer 12

• Nicotinamide
• Ribose
• Adenine + ribose = Adenosine

Question 13

What provides the nicotinamide part of the NAD+ molecule? How do we get it

Answer 13

Vitamin B3 (niacin)
Needs to be provided in the diet

Question 14

What does lack of niacin cause?

Answer 14

• Pellagra:

* Sensitivity to sunlight, dermatitis, alopecia, glossitis, weakness, ataxia, purple tongue

Question 15

Describe glycolysis in aerobic conditions

Answer 15

• NAD+ is regenerated because NADH passes the electrons and hydrogen atoms from glyceraldehde 3-P through the electors transport chain
• Electron transport chain combines them with oxygen to from water

Question 16

Describe glycolysis in anaerobic conditions

Answer 16

• NADH builds up because NAD+ can’t be regenerated

* If this situation persisted, glycolysis would halt

Question 17

What happens when not enough NAD+ is being regenerated?

Answer 17

• NADH is re-oxidised by reducing pyruvate to lactate

Question 18

How do yeast regenerate NAD+ in anaerobic conditions?

Answer 18

Converts pyruvate to ethanol

Question 19

What are the key enzymes involved in glycolysis?

Answer 19

1. Hexokinase: catalyses glucose to glycose 6 phosphate
2. Phosphofructokinase: catlayses fructose 6 phosphate to fructose-1,6-bisphosphate
3. Pyruvate kinase: catalyses phosphoenolpyruvate to pyruvate

Question 20

What is the most important enzyme in glycolysis and how is it regulated?

Answer 20

Phosphofructokinase
1. high ATP allosterically inhibits the enzyme

2. Low pH inhibits the enzyme (lactate accumulation)
3. High citric acid inhibits
4. High fructose 6 phosphate stimulates the enzyme