7.2 - Energy for action

Question 1

How many phospholipid membranes does a mitochrondria cell have?

Answer 1

2

Question 2

What are the 2 characteristics of the outer membrane of a mitochondria?

Answer 2

1. smooth
2. permeable to several small molecules

Question 3

What are the 4 characteristics of the inner membrane of a mitochondria?

Answer 3

1. folded (cristae)
2. less permeable
3. site of electron transport chain
4. location of ATP synthase

Question 4

What are the 2 characteristics of the intermembrane space?

Answer 4

1. low pH - due to high conc of protons
   2.

Question 5

What are the 2 characteristics of the matrix in the mitochondria?

Answer 5

• it is an aqueous solution within the inner membranes of the mitochondrion
• contain ribosomes, enzymes & circular mitochondrial DNA necessary for mitochondria

Question 6

What is the first reaction of substrate-level respiration?

Answer 6

glycolysis

Question 7

What are the 2 reactions which take place during glycolysis?

Answer 7

• phosphorylation
• oxidation

Question 8

What happens during the phosphorylation reaction, of glycosis?

Answer 8

• glucose is phosphorylated by adding 2 phosphates from 2 molecules of ATP
• increases the reactivity of glucose
• the molecules are then split into 2 molecules of 3C intermediate compounds
• 2 ADP are also made

Question 9

What happens in the oxidation react, of glycosis?

Answer 9

1. triose phosphates are oxidised forming 2 molecules of pyruvate
2. 2 hydrogen ions are also removed
3. Coenzyme NAD+ collects the hydrogen ions, to form 2 reduced NAD molecules

Question 10

Why is the Krebs cycle often reffered to as cyclical or circular?

Answer 10

the acceptor molecule oxaloacetate can be regenerated, in order to combine with another Acetyl CoA

Question 11

The outer mitochondrial membrane is not permeable to hydrogen ions (H+).
Explain the importance of this feature of the membrane.

Answer 11

• prevents the H+ diffusing out of the mitochondria
• this maintains a high concentration of H+ in the intermembrane
• H+ can move down the electrochemical gradient through ATP synthase
• this means that ATP synthase can catalyse ATP synthesis

Question 12

Where does the Krebs cycle take place in a mitochondrion cell?

Answer 12

matrix

Question 13

Where does oxidative phosphorylation take place in a mitochondrion cell?

Answer 13

cristae - in the inner mitochondrial membrane

Question 14

Why during anaerobic respiration might the blood lactate concentration stop increasing?

Answer 14

oxygen supply becomes sufficient for aerobic respiration because heart rate increases
this means that lactate is broken down by the liver