C1.2 Cell respiration - detailed steps

Question 1

Why humans produce lactate?

Answer 1

to regenerate the NAD from NADH

Question 2

What are the stages of glycolysis?

Answer 2

• glucose is phosphorylated with use of 2 ATP molecules
• lysis: glucose splits in half (3 carbon)
• removing hydrogen and oxidation of each G3P molecule which reduces two molecules of NAD to NADH
• products: 4 ATP, 2 pyruvate, 2 NADH

Question 3

What are the stages of link reaction?

Answer 3

• pyruvate is transported into matrix
• decarboxylation of pyruvate into acetyl
• acetyl is oxidised (lost H) and NAD is reduced to NADH
• formation of acetyl-CoA

Question 4

What are the stages of Krebs cycle?

Answer 4

• acetyl CoA and 4C compound (oxaloacetate) makes 6C compound (citrate)
• CoA is released
• 6C returns to 4C with products: two CO2, 3 NADH, 1 FADH2, 1 ATP

Question 5

What are the stages of the electron transport chain?

Answer 5

• hydrogen carriers release electrons
• chain uses energy from electrons to move H ions out of matrix
• H ions return to matrix via ATP synthase
• oxygen removes electrons and H ions