Respiration

Question 1

Describe the stages of glycolysis in aerobic respiration

Answer 1

In the cytoplasm of cells
•Glucose is phosphorylated to glucose phosphate using 2 ATP molecules
•Glucose phosphate splits into 2 triose phosphate
•Dehydrogenase catalyses the oxidation of triose phosphate into pyruvate with a net gain of 2 ATP and NADH (reduced NAD)

Question 2

Describe the stages of the link reaction in aerobic respiration

Answer 2

Pyruvate is actively transported into the mitochondrial matrix
•Dehydrogenase catalyses oxidation of pyruvate (3C) into acetate (2C), producing NADH (reduced NAD)
•Decarboxylase catalyses loss of CO2 in the process
•Acetate combines with coenzyme A to produce acetyl coenzyme A
•Acetylcoenzyme A reacts with a 4 carbon molecule, releasing co enzyme A and producing a 6C molecule that enters the kerbs cycle

Question 3

Deceive the stages of the krebs cycle in aerobic respiration

Answer 3

For both acetylcoenzyme A in the matrix
•Acetylcoenzyme A reacts with a 4 carbon molecule, releasing co enzyme A and producing a 6C molecule
•Dehydrogenase catalyses the oxidation of 6C molecule producing NADH (reduced NAD)
•Decarboxylase catalyses the loss of CO2 in the process
•Dehydrogenase catalyses the oxidation of 5C molecule producing 2 NADH and FADH
•Decarboxylase catalyses the loss of CO2 in the process
•ATP generated by substrate-level phosphorylation

Question 4

Describe the stages of oxidative phosphorylation in aerobic respiration

Answer 4

Chemiosmotic theory at inner mitochondrial membrane
•NADH and FADH release electrons to electron transfer chain (ETC)
•Electrons pass through ETC by a series of redox reactions
•Energy released used to pump H+ (protons) across inner mitochondrial membrane into intermembrane space
•H+ ions diffuse down electrochemical gradient, through ATP synthase embedded in the membrane, back into the matrix
•ATP synthase catalyses ATP by condensing ADP and Pi in oxidative phosphorylation
•O2 acts as a terminal electron acceptor from ETC producing water

Question 5

Describe anaerobic respiration in humans

Answer 5

Glycolysis
•Pyruvate reduced by NADH to lactate
•This regenerates NAD
•NAD used in glycolysis

Question 6

Describe anaerobic respiration for yeast/plants/microbes

Answer 6

Glycolysis
•Pyruvate reduced by NADH to ethanol and CO2
•This regenerates NAD
•NAD used in glycolysis