respiration

Question 1

glycolysis

Answer 1

occurs in both aerobic + anaerobic respiration (doesnt require O2)

occurs in cytoplasm

• glucose (6C) phosphorylated into hexose bisphosphate, using 2 ATP
• unstable so splits into 2 TP (3C)
• each TP oxidised into a pyruvate molecule (3C)
• H picked up by 2 NAD to make 2 reduced NAD
• releasing 4 ATP

net gain: 2 ATP, 2 NADH, 2 pyruvate

Question 2

link reaction

Answer 2

occurs in matrix

• 2 pyruvate decarboxylated, releasing 2 CO2 and oxidised further, reducing 2 NAD, to make 2 acetate (2C)
• actetate combines by coenzyme A to make acetylcoA (2C)

net gain: 2 CO2, 2 NADH, 2 acteyl coA, no ATP

Question 3

krebs cycle

Answer 3

occurs in matrix

• acetylcoA combines w oxaloacetate (4C) to form citrate (6C)
• releasing coA (to be reused in the link reaction)
• citrate decarboxylated, releasing CO2 + oxidised (reducing NAD to NADH) to form a 5C molecule
• 5C molecule converted to oxaloacetate (4C) via series of oxidation + reduction reactions

produces:
per cycle - 3 NADH, 1 FADH, 1 ATP, 2 CO2
per glucose - 6 NADH, 2 FADH, 2 ATP, 4 CO2

NADH + FADH used in OP
ATP used for energy
CO2 released as waste

Question 4

oxidative phosphorylation

Answer 4

occurs in inner membrane

• all the reduced coenzymes accumulate in the mitochondrial matrix where they release their H atoms which split into protons + electrons
• electrons passed down ETC, releasing energy at each carrier
• energy released used to pump protons from matrix into intermembrane space via AT
• this creates an electrochemical gradient across the membrane
• so protons can move down this gradient back into matrix via ATP synthase, making ATP from ADP and Pi (chemiosmosis)
• oxygen is the final electron acceptor in the ETC + combines w electrons + protons to form water

Question 5

anaerobic respiration

Answer 5

• ## glycolysis occurs as usual