Aerobic respiration

Question 1

What is aerobic respiration?

Answer 1

• releasing energy trapped in the bonds of the glucose molecule with sufficient oxygen

Question 2

What are the steps of aerobic reaction in order and where do they occur?

Answer 2

• glycolysis occurs in the cytoplasm
• link reaction occurs in the matrix
• Krebs cycle occurs on the inner membrane
• oxidative phosphorylation occurs on the inner membrane .. electron transport chain

Question 3

What happens in glycolysis?

Answer 3

• glucose is phosphorylated using two ATP molecules to form a very reactive and unstable 6C compound
• as this is very reactive, it undergoes lysis and splits into two triose phosphate molecules.
• the two triose phosphates get dephosphorylated and dehydrogenated to produce two pyruvate molecules
• this produces four ATP molecules and two reduced NAD

Question 4

What is the net gain of ATP molecules and why?

Answer 4

• although four ATP molecules are made when triose phosphate is converted to pyruvate, two were used at the start to phosphorylate glucose

Question 5

What happens in the link reaction?

Answer 5

Pyruvate + CoA + NAD&raquo_space;» acetyl CoA + CO2 + reduced NAD

Question 6

What is a coenzyme?

Answer 6

• a non protein enzyme helper derived from vitamins

- it either firms as part of the active site of enzymes or helps transfers atoms or functional groups between reactions

Question 7

What happens in the Krebs Cycle?

Answer 7

• The two carbon acetyl CoA combines with the four carbon molecule
• the CoA coenzyme is released
• six carbon molecule is produced
• for the six carbon molecule to go back to the four carbon, two CO2 are released, three reduced NAD formed, one reduced FAD and an ATP molecule

Question 8

What happens in the electron transport chain?

Answer 8

• the reduced NADs and FADs split releasing their H+ and electrons.
• the electrons are accepted by an electron carrier protein
• as the electron transfers to neighbouring electron carrier proteins, it loses energy
• this energy is used to pump the H+ ions donated by the reduced NAD and reduced FAD from the matrix to the space between inner and outer membrane
• as H+ move down their concentration gradient, they diffuse through ATP synthase enzymes which produce ATP molecules

Question 9

What parts of aerobic respiration also occurs in anaerobic respiration and why?

Answer 9

Glycolysis because oxygen isn’t needed for this stage

Question 10

What is oxygen described as in the electron transport chain?

Answer 10

• the final electron acceptor because it accepts the ejection once it reaches the end of the electron transport chain to form water which is also a product of aerobic respiration