3.5.2 - Respiration

Question 1

What are the 4 stages of aerobic respiration and where do they occur ?

Answer 1

• Glycolysis - cytoplasm
• Link reaction - mitochondrial matrix
• Krebs cycle - mitochondrial matrix
• Oxidative phosphorylation - mitochondiral inner membrane cristae

Question 2

What is glycolysis ?

Answer 2

The first stage of anaerobic and aerobic respiration
- It doesnt require energy, O2 or ATP to actively transport it into the mitcohondria

Question 3

Steps of glycolysis (1)

Answer 3

1) Phosphorylation of glucose, ATP will hrydrolyse a phosphate group and add it to glucose. 2 ATP is used to do this. - Add 2 phosphate groups to glucose - glucose phospate

Question 4

Glycolysis (2)

Answer 4

Glucose phosphate is very high energy so it splits into two molecules of triosphosphate

Question 5

Glycolysis (3)

Answer 5

Triosphosphate is oxidised into pyruvate with a net gain of 2 ATP and 2 NADH

Question 6

What does gaining a hydrogen show ?

Answer 6

It shows that it is reduced as a H+ atom is a proton and an electron

Question 7

What are the products of glycolysis ?

Answer 7

2 x pyruvate
net gain of 2 ATP
2 x NADH

Question 8

In areobic respiration, where does the pyruvate made in glycolysis go ?

Answer 8

It is actively transported into the mitochondrial matrix for the next step.

Question 9

The stages of the LINK REACTION

Answer 9

• The pyruvate made is decarboxylated and oxidised to form acetate.
• NAD is reduced, forming NADH.
• Acetate combines with CoA to make acetyl CoA.

Question 10

What are the products made in this stage ?

Answer 10

• 2 x Accetylcoenzyme A
  -2 x CO2
• 2 x Reduced NAD
  2 of each as the reaction occurs twice to create two pyruvates

Question 11

The stages of the KREBS CYCLE
(1)

Answer 11

• Acetyl coA combines w/ 4c molecule (oxaloacetate), forming 6c citrate.
• CoA goes back to link reaction to be used again.

Question 12

The stages of the KREBS CYCLE
(2)

Answer 12

• The 6c citrate is converted into a 5c molecule
• Decarboxylation occurs, as well as dehydrogenation so both CO2 and H are removed.
• The H is used to produce NADH

Question 13

The stages of the KREBS CYCLE
(3)

Answer 13

The 5c molecule is converted into a 4c molecule.
- Decarb & Dehyd occur, producing one molecule of FADH and 2x NADH
- ATP = produced by direct transfer of phosphate group from intermediate compound to ADP.

Question 14

What is substrate - level phosphorylation ?

Answer 14

When a phosphate group is directly transferred from one mol to another.

Question 15

The products of the KREBS cycle are …?

Answer 15

Per cycle :
- 3 x NADH
- 1 x FAD
- 1 x ATP
- 2 x CO2
per glucose - multiply all by 2

Question 16

What is oxidative phosphorylation ?

Answer 16

The process where energy carried by electrons from reduced coenzymes (NADH and FADH) is used to make ATP.

Question 17

How does OX. PHOS. work ?
Steps 1 - 2

Answer 17

1) H atoms are released as NADH and FADH are oxidised to NAD and FAD. The H+ ions split into protons and e-
2) Electrons move down the ETC ,losing energy at each step.

Question 18

How does OX. PHOS. work ?
Steps 3-4

Answer 18

3) the energy is used by electron carriers to pump protons from the matrix into intermembrane space
4) The con of protons is higher in the space than the matrix, forming an electrochemical gradient

Question 19

How does OX. PHOS. work ?
Steps 5-6

Answer 19

5) Protons move down the gradient, across the inner membrane and into the matrix via ATP synthase. - ATP is synthesised here from ADP and Pi
6) The forming of the ATP is driven by H+ ions moving across a membrane - chemiosmosis.

Question 20

How does OX. PHOS. work ?
Step 7

Answer 20

In the mito matrix, at the end of the ETC, protons, e- and O2 combine to form water.
Oxygen is the final e- acceptor

Question 21

What can ATP production be affected by ?

Answer 21

Mitochondrial diseases which affect the functioning of mitochondria.
they effect how proteins in ox. phos. or Kreb’s cycle function which reduces ATP production.

Question 22

What causes an increase lactate concentration in the blood ?

Answer 22

Mitochondrial diseases can cause anaerobic respiration to increase and lots of lactate therefore builds up, causing muscle fatigue and weakness.
Some diffuses into bloodstream leading to a high con of lactate.

Question 23

What can other respiratory substances be used for ?

Answer 23

Other respiratory substances can be used in aerobic respiration.
Some products resulting from the breakdown of other molecules : fatty acids, AAs - can be converted into molecules able to enter Kreb’s.