Metabolism Glycolysis

Question 1

Define metabolism.

Answer 1

enzyme reactions organised into pathways which interconnect into networks.

Question 2

ATP is a free energy donor to the processes of…

Answer 2

• anabolism/biosynthesis
• mechanical work/movement
• active molecular transport

Question 3

How is free energy liberated?

Answer 3

Hydrolysis of ATP.

Question 4

Give the roles of NADH.

Answer 4

• transfers electrons away from food source and transfers them to pathways that generate energy and build up complex molecules
• NAD+ and NADP+ are the major e- acceptors in biological systems

Question 5

What is key to generating energy?

Answer 5

movement of e-

Question 6

Describe the stages of fuel molecule degradation.

Answer 6

1. Digestion & hydrolysis
   - breakdown of complex molecules
2. Conversion
   - breaking down to 2-,3-carbon compounds & acetyl CoA
3. Oxidation
   - oxidation of acetyl CoA via citric cycle and e- flow to O2 via NADH

Question 7

Give the overall process of what happens to nutrients in the body.

Answer 7

1. Oxidation to generate energy (catabolism)
2. Storage until required
3. Conversion into something more useful

Question 8

Give the 2 ways in which NAD+ is regenerated.

Answer 8

Lactate hydrogenase

Oxidative phosphorylation

Question 9

How is metabolism controlled?

Answer 9

• controlling select key enzymes
• irreversible enzymes, enzymes at the start of a pathway/branchpoint, or rate-limiting enzymes are controlled
• controlled by altering levels of synthesis of key enzymes or activity of key enzymes

Question 10

Give the rate limiting step in glycolysis.

Answer 10

Fructose-6-phosphate to fructose-1,6-biphosphate.

Requires phosphofructokinase & 1 ATP.

Question 11

Give the 3 key stages of glycolysis.

Answer 11

• investment
• oxidation of glyceraldehyde-3-phosphate
• energy generation

Question 12

Give the 3 reactions in the investment stage.

Answer 12

-Glucose receives phosphate group from ATP
-Glucose-6-phosphate is isomerised
-Fructose-6-phosphate is phosphorylated
>Fructose-1,6-biphosphate

Question 13

Give the reaction in the oxidation stage.

Answer 13

Fructose-1,6-biphosphate cleaved into 2x 3C molecules

>Glyceraldehyde-3-phosphate

Question 14

Give the 5 reactions in the energy generation stage.

Answer 14

• Oxidation of aldehyde group
• Phosphoryl group removed from 1,3-bisphosphoglycerate to make ATP
• Phosphoryl group shifted from C3 to C2
• Dehydration of 2-phosphoglyercate elevates transfer potential
• Phosphoryl group removed from phosphoenolpyruvate to make ATP.