Respiration

Question 1

Describe structure of mitochondria?

Answer 1

Double membrane –> compartmentalisation

Inner membrane –> holds different proteins for ETC

Cristae –> folded inner membrane. Increases SA for oxidative phosphorylation

Inter membrane space –> ETC pumps H+ into space (H+ conc) for ATP synthesis

Matrix –> liquid in cristae –> contains enzyme for link + Krebbs cycle
Contains mitochondrial DNA

Question 2

What is glycolysis?

Answer 2

Cytoplasm

Glucose –> hexose bisphosphate

2ATP molecules used

Hexose bisphosphate (split)
–> triose phosphate

Triose phosphate + pi = triose bisphosphate

Triose bisphosphate + 2 ADP + 2 NAD = 2 pyruvate molecules

Question 3

What is substrate level phosphorylation?

Answer 3

the formation of ATP without the involvement of an electron transport chain.

ADP phosphorylated by unstable intermediate (triose bisphosphate) to form ATP

Question 4

What is the net gain of ATP in glycolysis?

Answer 4

2

Question 5

What is the link reaction?

Answer 5

Pyruvate moved into mitochondrial matrix –> AT

CO2 removed = decarboxylation

H removed
(form NADH) = dehydrogenation

Combined with coenzyme A = acetyl coA

Controlled by pyruvate dehydrogenase

Question 6

What is the Krebs cycle?

Answer 6

Acetyl coA + oxaloacetate (4 C) = citrate (6C)

Loses C in form of CO2 –> decarboxylation

= ketoglutarate (5 C)

NADH

5 C molecule loses another C as CO2

NADH

FAD = FADH2

ATP made for energy

Regenerate OG 4C molecule.

Question 7

What is the net of Krebs Cycle?

Answer 7

1 ATP

3 NADH

1 FADH

Question 8

What is oxidative phosphorylatio?

Answer 8

1. Reduced NAD/FAD release H+ and e-
2. e- enter ETC
3. Electrons release energy along ETC.

4.Energy used to pump protons by AT across cristae into inter membrane space

5. Proton concentration increase in IM space –> generate proton concentration
6. Chemiosmosis occurs –> H+ move across ATP synthase

Question 8

What is chemiosomosis?

Answer 8

Net movement of protons down electrochemical gradient through ATP synthase

Makes ATP

Question 9

Why is H+ not allowed to stay in cristae?

Answer 9

More acidic

Denature ATP synthase + electron carriers

Question 10

What is the role of oxygen?

Answer 10

Final electron acceptor

Reacts with protons + electrons = water

Question 11

What is anaerobic respiration?

Answer 11

Breaking down larger molecules into simpler molecules using no oxygen or ETC

Goes through glycolysis

Question 12

Describe lactate fermentation?

Answer 12

Pyruvate —> Lactate

NADH –> NAD

Requires lactate dehydrogenase

Lactate + O2 in liver –> glucose

Uses 6 ATP

Net loss of 4 ATP

Question 13

Describe alcoholic fermentation in plants/yeast?

Answer 13

Pyruvate –> ethanal –> ethanol

Lose CO2 to make ethanal (pyruvate decarboxylase)

Ethanal gains H to ethanol

NADH
~~> uses ethanol dehydrogenase

irreversible

Question 14

Name other respiratory substrates besides glucose?

Answer 14

Triglycerides –> glycerol (pyruvate) + 3 fatty acids (500 ATP) -= lots of energy

Protein –> amino acids
(deamination into pyruvate)

Question 15

Why is protein not a good respiratory substrate?

Answer 15

Uses ATP

Decreases loss ATP production

Decrease in muscle mass

Question 16

What is the respiratory quotient (RQ)?

Answer 16

CO2 produced / O2 absorbed

Carb : 1.0

Lipid : 0.7

Protein : 0.9

Question 17

How much ATP produced from 1 glucose molecule?

Answer 17

net gain = 38

Question 17

NAD vs FAD:

Answer 17

NAD:
All stages

Accepts 1H+

oxidised at start of ETC

1 NADH = 3 ATP

FAD:
involved only in Krebs

Accepts 2H+

oxidised further along ETC

1 FADH = 2 ATP