Respiration

Question 1

Define respiration

Answer 1

The process in living organisms involving the production of energy, typically with the intake of oxygen and the release of carbon dioxide from the oxidation of complex organic substances.

Question 2

Define metabolism

Answer 2

The sum total of all chemical reactions that occur in the body

Question 3

What is anaerobic vs aerobic respiration?

Answer 3

Anaerobic is respiration that does NOT require O2

Aerobic = respiration that requires O2

Question 4

What are the 4 main steps of cellular respiration?

Answer 4

Glycolysis
Link Reaction
Krebs/ Citric acid cycle
Oxidative phosphorylation (aka electron transport chain)

Question 5

What are the 4 main stages of Glycolysis?

Answer 5

1) phosphorylation of glucose
2) Lysis (splitting) of phosphorylated glucose
3) Oxidation of triose phosphate
4) ATP formation

Question 6

What are the products of glycolysis?

Answer 6

2x Pyruvate (3C)
4x ATP (but only 2 are gained)
2x NADH
2x H+

Question 7

Where does glycolysis happen?

Answer 7

In the cytosol of the cell (aka cytoplasm)

Question 8

Where does the link reaction happen?

Answer 8

In the matrix of the mitochondria

Question 9

What are the main stages of the link reaction?

Answer 9

1) Pyruvate is oxidised, so NAD is reduced

2) Pyruvate is decarboxylated

Question 10

What are the products from the link reaction?

Answer 10

2x Acetyl CoA (2C)
2x Co2
2x NADH
2x H+

Question 11

Where does the Krebs cycle happen?

Answer 11

In the matrix of the mitochondria

Question 12

What is the main process of the Krebs cycle?

Answer 12

1) Acetyl CoA binds with a 4C sugar to make citrate (6C) - NAD oxidises this (and is reduced to NADH)
2) Citrate is decarboxylated (becomes 5C)
3) The 5C sugar is oxidised by more NAD and FAD (they become reduced)
4) The 5C sugar is decarboxylated again (becomes 4C) - 1 ATP molecule is produced
5) The 4C sugar is added to the next CoA to continue the cycle

Question 13

What are the products of the Kerbs cycle per 2 pyruvate molecules?

Answer 13

4x CO2
2x ATP
2x FADH2
6x NADH + H+

Question 14

What products starts off in glycolysis?

Answer 14

Glucose - 6C molecule

Question 15

What product starts off the link reaction?

Answer 15

2x Pyruvate (3C molecules)

Question 16

What product starts of the Krebs cycle?

Answer 16

2x Acetyl CoA (2C molecules)

Question 17

What products are used to start off the electron transport chain?

Answer 17

Hydrogen protons

Question 18

Where does oxidative phosphorylation happen?

Answer 18

Inner mitochondrial membrane (cristae)

Question 19

What is oxidative phosphorylation?

Answer 19

The formation of ATP by adding a phosphate group to ADP, in the presence of oxygen

Question 20

What does the electron transport chain do?

Answer 20

Releases energy stored in the hydrogen carriers to synthesise ATP through oxidative phosphorylation

Question 21

What are the basic steps of oxidative phosphorylation?

Answer 21

1) Proton pumps create electrochemical gradient (proton motive force)
2) ATP synthase uses the subsequent diffusion of protons (chemiosmosis) to synthesis ATP
3) Oxygen is reduced, accepting electrons and protons – forms water

Question 22

How is the proton motive force generated?

Answer 22

1) NADH and FADH2 are oxidsed, releasing high energy electrons and protons
2) The electrons pass through the ETC, losing energy to the chain to pump protons from the matrix
3) Protons collected in the intermembrane space create electrochemical gradients - the proton motive force

Question 23

How does chemiosmosis synthesis ATP?

Answer 23

1) H+ protons are diffused back to the matrix by proton motive force
2) The diffusion is called chemiosmosis
3) The protons move through ATP synthase, triggering enzyme rotation and phosphorylation reaction - causes synthesis of ATP

Question 24

What is the role of oxygen in oxidative phosphorylation?

Answer 24

It acts as an electron acceptor

It removes de-energized electrons (becomes reduced) - forming water to maintain the hydrogen gradient

Question 25

What is chemiosmosis?

Answer 25

The flow of hydrogen ions (protons) across a membrane

Question 26

How many ATP molecules are produced from one glucose molecule in aerobic respiration?

Answer 26

38