Respiration (A-level only)

Question 1

Glycolysis

Answer 1

Happens in cytoplasm

ATP hydrolase breaks down 2 ATP to make 2 lots of ADP and pi

Glucose is phosphorylated into the more reactive glucose phosphate

Glucose phosphate is then converted into to GP and then splits onto 2 TP

TP is oxidised to form pyruvate and the released hydrogen reduces NAD

This release energy which is used to convert ADP and pi to produce 4 ATP

Question 2

Anaerobic vs Aerobic respiration

Answer 2

If respiration is only anaerobic, pyruvate can be converted to ethanol or lactate using reduced NAD. The oxidised NAD produced in this way can be used in further glycolysis.

If respiration is aerobic, pyruvate from glycolysis enters the mitochondrial matrix by active transport

Question 3

Link reaction

Answer 3

Happens in the matrix

Pyruvate release carbon dioxide and hydrogen to form acetate

Hydrogen the reduces NAD

Coenzyme A combines to acetate to form acetylCo enzyme A

Question 4

Kerbs cycle

Answer 4

This happens in the matrix

Acetyl coA combines with a 4 carbon molecule to produce a 6 carbon molecule

The 6 carbon molecule release carbon dioxide and hydrogen into a 5 carbon molecule

The hydrogen oxidised NAD into NADH2

The 5 carbon molecule does the same and the redox reaction release energy to produce ATP

The 4 carbon molecule release hydrogen to reduce FAD

Question 5

Oxidative phosphorylation

Answer 5

The reduced coenzymes (NAD/ FAD) release hydrogens which are photo ionised into protons and electrons

The electrons are transferred along the ETC in a series of redox reactions and the energy released is used to pump protons across the cristae into the the interemembrane space

This creates an electrochemical gradient so protons diffuse out through ATP synthase and activate it

ATP synthase phosphorylates many ADP into ATP

At the end oxygen acts as the final acceptor and is reduced by the protons and electrons to produce water