12- respiration

Question 1

Other respiratory substrates

Answer 1

• fatty acids> Acetyl CoA

- Amino acids> Krebs cycle

Question 2

importance of oxygen

Answer 2

if no oxygen to ACCEPT electrons, electrons cannot be passed along ETC

Question 3

Where does glycolysis occur?

Answer 3

cytoplasm

Question 4

what are the 3 stages of glycolysis?

Answer 4

1. Phosphorylation of glucose> GP (using Pi’s from 2xATP)
2. This is hydrolysed to 2x TP
3. 2x TP oxidised to 2x pyruvate (2 NAD reduced to NADH, 4 ATP regenerated)

Question 5

What is the net gain of glycolysis?

Answer 5

2 x ATP, 2x NADH

Question 6

Anaerobic respiration can either be ______________ or ____________-

Answer 6

lactate fermentation, ethanol fermentation

Question 7

what are the stages of anaerobic respiration? (3)

Answer 7

1. pyruvate converted to either lactate or ethanol
2. This causes oxidising of NADH> NAD
3. Glycolysis can continue (due to regeneration of NAD)

Question 8

Stages in aerobic respiration: (3)

Answer 8

1. Link reaction
2. Krebs cycle
3. Oxidative phosphorylation

Question 9

what happens to pyruvate before the link reaction can occur?

Answer 9

pyruvate actively transported into MM from the cytoplasm

Question 10

What are the stages of the link reaction? (3)

Answer 10

1. Pyruvate oxidised and decarboxylated to acetate
2. Co2 and NADH produced
3. Acetate combines with coenzyme A to produce Acetyl coenzyme A

Question 11

how many times does the link reaction occur to create 1 molecule of glucose?

Answer 11

twice

Question 12

Where does the Krebs cycle occur?

Answer 12

Mitochondrial matrix

Question 13

What are the stages of the Krebs cycle? (4)

Answer 13

1. Acetyl coenzyme A reacts with a 4C molecule to form a 6C molecule (CoA recycled in link)
2. 6C > 4C via a series of redox reactions
3. This releases CO2 & forms 1x FADH2 & 2x NADH
4. ATP is produced from substrate-level phosphorylation

Question 14

Where does oxidative phosphorylation occur?

Answer 14

Inner mitochondrial membrane/ cristae

Question 15

What are the stages of oxidative phosphorylation? (7)

Answer 15

1. Reduced NAD/FAD oxidised to release H atoms (which are split into protons (H+) and electrons (e-)
2. Electrons are transferred down the ETC by redox reactions
3. Energy released by the e- is used in production of ATP from ADP+Pi
   (chemiosmotic theory)
4. Energy also used to AT protons from matrix to intermembrane space
   5.Protons diffuse down electrochemical gradient, via ATP synthase back into matrix
5. This releases energy to combine ADP+Pi > ATP
6. In MM at end of ETC, oxygen is final electron acceptor

Question 16

What other respiratory substrates can be used for aerobic respiration?

Answer 16

Fatty acids> Acetyl CoA

Amino acids> Krebs cycle