Cell metabolism

Question 1

Learning objectives

Answer 1

Learn
(i) Names of reactants , enzymes etc that are explicitly mentioned in the lectures

(ii) Flow of energy, where energy, electrons carriers are made, how many etc

(iii) Key elements of how glycolysis in controlled

(iv) The general structure of the TCA cycle - ie the number of carbons at different points, where electron carriers and CO2 are produced

(v) Key cellular compartments where different types of metabolism take place

(vi) How different types of metabolism occur in different tissues

Question 2

Key elements of how glycolysis.
What is glycolysis?
Describe the 2 phases of glycolysis.
What is the net production of glycolysis?

Answer 2

glycolysis - degradation of glucose to pyruvate
glycolysis process results in formation of ATP and NADH

2 phases of glycolysis:
preparation phase:
- Conversion of one 6-carbon molecule (glucose) into two 3-carbon molecules of G3P
PREPARATION PHASE CONSUMES 2 MOLECULES OF ATP

Payoff phase:
- Conversion of G3P to pyruvate
PRODUCES 4 molecules of ATP and 2 molecules of NADH

net production of glycolysis = 2ATP AND 2 NADH molecules

Question 3

Key elements of how glycolysis is controlled

Answer 3

Glycolysis is controlled by inhibition of pyruvate kinase

Pyruvate kinase is inhibited by ATP and Acetyl-CoA
Pyruvate kinase is activated by FBPase

Starting reactants promote conversion to Acetyl-CoA (positive feedback)

BUT

Products inhibit conversion to Acetyl-CoA(negative feedback)

Question 4

What happens in the Krebs/TCA cycle?

Answer 4

2-carbon Acetyl-CoA is fed into this cycle and joined with a four carbon molecule to produce a 6-carbon molecule

In oxidation phase - pulling off electrons and carbons into intermediates like NADH and FADH2
- this reduces 6-C molecule down to a 4-C molecule
The 4-C molecule can be recycled

Question 5

Explain metabolism in muscle