Respiration

Question 1

What is respiration ?

Answer 1

Respiration is the process by which cells break down simple food molecules, such as sugar, and release the energy they contain.

Question 2

What is glycolysis ?

Answer 2

Oxidative break down of glucose to pyruvate

Question 3

Give a summary of glycolysis ?

Answer 3

1. Glycolysis takes place in cytoplasm
2. Glucose is broken down into pyruvate
3. Oxygen is not involved
4. Only a small amount of energy is released
5. Glycolysis produces both ATP and NADPH

Question 4

What occurs to the pyruvate 3C after glycolysis ?

Answer 4

-Under anaerobic conditions pyruvate undergoes fermentation
-Fermentation can produce ATP in the absence of oxygen.
- Designed to recycle the NADH so that glycolysis can continue.

Question 5

Where does the TCA cycle occur ?

Answer 5

In the matrix of the mitochondria

Question 6

Where is the electron transport chain located ?

Answer 6

In the inner mitochondrial membrane

Question 7

What does the TCA cycle generates ?

Answer 7

Generates NADH and FADH2 that are passed on to electron - transport chain

Question 8

What is NADH and FADH are oxidised back to in the electron transport chain ?

Answer 8

NAD and FAD

Question 9

Explain the process of oxidative phosporylation ?

Answer 9

Electrons from NADH pass down a series of electron carriers and are donated to oxygen to form water
- These carriers are organised into groups of carriers complexes
- Associated with these complexes are proton (H+) pumps
- These proton pumps pump protons out of the mitochondria and thus set up a gradient across the inner membrane
- This proton gradient is used to provide the energy for ATP synthesis
- This process is termed OXIDATIVE PHOSPHORYLATION

Question 10

What does the TCA cycle generates ?

Answer 10

High energy electrons carried by activated carrier molecules NADH and FADH that are passed on to electron transport chain

Question 11

What does the movement of electrons coupled with the pumping of protons create ?

Answer 11

A steep proton gradient

Question 12

What does Atp synthase use to produce ATP ?

Answer 12

ATP synthase uses the energy stored in the electrochemical proton gradient to produce ATP

Question 13

During NADH oxidation what does an electron pair cause ?

Answer 13

Causes 10 protons to be pumped across the membrane

Question 14

For each NADH in the oxidative phosphorylation process how many ATP are produced ?

Answer 14

2.5

Question 15

What is the total amount of ATP produced in respiration ?

Answer 15

30

Question 16

Explain why NADPH produced in the cytosol yields fewer ATP than NADH produced in mitochondria ?

Answer 16

As mitochondrial inner membrane is not permeable to NADH

Question 17

What else does respiration do other than providing energy ?

Answer 17

Intermediates are withdrawn from these pathways to provide the carbon for the synthesis of a large number of macromolecules

Question 18

What are the 3 enzyme steps that control the TCA cycle ?

Answer 18

• PYRUVATE DEHYDROGENASE
• inhibited by ATP, ACETYL CoA and NA
• ISOCIRATE DEHYDROGENASE
  -inhibited by NADH and ATP
• activated by ADP
• KETOGLUTARATE DEHYDROGENASE
  Inhibited by NADH, ATP and Succinylcholine CoA

Question 19

What are the 3 steps in glycolysis that controls it and can’t be reversed ?

Answer 19

• HEXOKINASE
  -PHOSPHOFRUCTOKINASE
  -PYRUVATE KINASE

Question 20

What is HEXOKINASE controlled by ?

Answer 20

• GLC - 6- PHOSPHATASE

Question 21

What is PHOSPHOFRUCTOKINASE controlled by ?

Answer 21

FRUCTOSE-1,6-BISPHOSPHATASE

Question 22

What is pyruvate kinase controlled by ?

Answer 22

pep carboxykinase

Question 23

What allows cells to switch from glucose breakdown to glucose synthesis ?

Answer 23

Feedback regulation

Question 24

Whats the main mechanism that used to maintain glucose levels in the blood ?

Answer 24

GLUCONEOGENSIS
Occurs when pyruvate, lactate, glycerol and some amino acids get converted to glucose due to fasting, starvation and intense exercise.

Question 25

What is the key mechanism in recycling lactate ?

Answer 25

Lactate generated primary in muscle cells during intense exercise
- Lactate is moved to liver where it is converted to glucose through GLUCONEOGENESIS
Glucose then returns to the muscle cells where it is used for glycolysis.