Aerobic respiration

Question 1

what does the krebs cycle do

Answer 1

produces reduced coenzymes and ATP

• undergoes a series of redox reactions which take place in the matrix.
• cycle happens once for every pyruvate molecule and TWICE for every glucose molecule

Question 2

KREBS CYCLE

Answer 2

1) Acetyl group from acetyl CoA combines with oxaloacetate, to FORM CITRATE, (catalysed by citrate synthase)

2) 6C - > 5C , citrate gets decarboxlyated
- dehydrogenation also occurs ( hydrogen are removed)
- The hydrogen is used to produce NADH from NAD.

3) 5C -> 4C
- decarboxylation and dehydrogenation occur, producing reduced FAD, and 2NADH

• ATP produced: when a phosphate group is transferred from the intermediate compound, to ADP.
  CITRATE has now been converted into OXALOACETATE

Question 3

what is substrate level phosphorylation

Answer 3

when phosphate groups are directly transferred from one molecule to another.

Question 4

Where do the products from the krebs cycle go?

Answer 4

6 products from krebs:

1) coenzyme A used in the next link reaction
2) Oxaloacetate: used un the next krebs cycle
3) 2CO2: Waste product
4) 1ATP: used for energy
5) 3NADH- goes to oxidative phosphorylation stage
6) 1 reduced FAD( FADH): Goes to oxidative phosphorylation

Question 5

what is oxidative phosphorylation

and where does it take place?

Answer 5

• where the energy carried by electrons, from coenzymes ( reduced NAD-FAD) is used to make ATP
• oxidative phosphorylation takes place in the matrix .

Question 6

Oxidative phosphorylation process

Answer 6

1) NADH and FADH release hydrogen atoms, oxidising into NAD and FAD. hydrogen splits into electrons and protons
2) These electrons move across the ETC, losing energy at each carrier
3) This energy is used to pump protons by the electron carriers , from the matrix to the intermembrane space .
4) Higher concentration of protons in intermembrane space than matrix, which produces an electrochemical gradient.
5) Protons move down the electrochemical gradient into the matrix via ATP synthase, which helps to synthesise ATP from ADP and pi
6) chemiosmosis- producing ATP from the movement of H+ ions across a membrane.
7) in the matrix at the end of the ETC, protons and electrons and oxygen combine to form water, oxygen is the final electron acceptor.

Question 7

how many ATP is produced per glucose molecule

Answer 7

32