18.2 - Glycolysis & Krebs Cycle

Question 1

What is the structure of mitochonodria?

Answer 1

Outer mitochondrial space: separates mitochondria contents from rest of cell, compartmentalising for aerobic respiration

Matrix: Contains enzymes for Krebs cycle and link reaction – also has mtDNA

Intermembrane space: Proteins pumped into this space by ETC. Conc. of the proteins builds up quickly due to its size

Inner mitochondrial membrane: Has ETC and ATP synthase

Cristae: Projections of inner membrane – increase the SA for oxidative phosphorylation

Question 2

What are the stages of the link reaction?

Answer 2

Known as oxidative decarboxylation

1. The pyruvate enters the mitochondrial matrix via active transport (using carrier proteins)
   
   1. Pyruvate undergoes oxidative decarboxylation – CO₂ removed along side a hydrogen (that is oxidation)
   2. The hydrogen is accepted by NAD (it is reduced).
2. Results in a 2 carbon acetyl group that binds to coenzyme A forming acetylcoenzyme A (acetyl CoA)
3. Acetyl CoA delivers the acetyl group to the next stage of aerobic respiration – the Krebs Cycle
4. NADH is used in oxidative phosphorylation
5. The carbon dioxide diffuses away or is removed as waste. In autotrophs the carbon dioxide may be used for photosynthesis