Week 1 - Cellular Energy Metabolism

Question 1

How is ATP generated?

Answer 1

• when the protons move down their concentration gradient via the ATP synthase, the synthase rotates
• the rotation produces the energy required to phosphorylate ADP

Question 2

What is the example of metabolic plasticity in respiration?

Answer 2

• when only the first two complexes work in the electron transport chain so electrons cannot be transported forward anymore
• the first complexes cannot take anymore electrons so NADH doesn’t get oxidised anymore to NAD+
• NAD+ is required to make NADH in the TCA cycle and to keep it going but the conditions are not ideal anymore
• because of this reductive carboxylation occurs, where the TCA cycle occurs backwards

Question 3

What does metabolism consist of?

Answer 3

• catabolism (breaking down)
• anabolism (building up)

Question 4

Where and how is energy stored in ATP?

Answer 4

• in the phosphodiester bonds
• because the oxygen in the phosphate molecules create a region of high negative polarity
• by breaking the bond the energy state is lowered
• thus releasing some of that energy

Question 5

What other biosynthetic outputs are there from the TCA cycle?

Answer 5

• aspartate for nucleotide synthesis
• fatty acids synthesis
• haem synthesis

Question 6

What does metabolic plasticity mean?

Answer 6

• when a change in function (perturbation) occurs in a metabolic network
• causes metabolic flux to a different pathway

Question 7

What is the glycolysis shuttle?

Answer 7

a system in which electrons are transported from the cytoplasm of a cell to the mitochondrial matrix for oxidative phosphorylation