Respiration

Question 1

What are the 4 stages of respiration?

Answer 1

Glycolysis, link reaction, Krebs cycle and oxidative phosphorylation

Question 2

Where does glycolysis take place?

Answer 2

Cytoplasm

Question 3

What are the products of glycolysis?

Answer 3

For every glucose molecule- 2 pyruvate, net production of 2ATP and 2 reduced NAD (NADH).

Question 4

What is reduced NAD also refered to as?

Answer 4

NADH

Question 5

Where does the link reaction take place?

Answer 5

In the mitochondrial matrix

Question 6

What is the structure of ATP?

Answer 6

3 phosphate groups, adenine (nitrogenous sugar) and a ribose (pentose sugar).

Question 7

What happens if you cut 1phosphate off ATP?

Answer 7

Make ADP

Question 8

What is the first stage in glycolysis?

Answer 8

Glucose (6C) is phosphorylated by 2 ATP to form hexose bisphosphate (6C).

Question 9

What is the second stage of glycolysis?

Answer 9

Hexose bisphosphate (6C) splits into two molecules of triose phosphate (3C). This process is called lysis.
A phosphate is then added to each of the triose phosphates.

Question 10

What is the third stage of glycolysis?

Answer 10

Hydrogen is removed from each of molecule of triose phosphate and transfered to coenzyme NAD to form 2 reduced NAD. This stage is called oxidation.

Question 11

What is the fourth stage of glycolysis?

Answer 11

Phosphates are transfered from triose phosphate and combinded with 4ADP to produce 4ATP. This is called dephosphorylation

Question 12

What is the produced at the end of glycolysis?

Answer 12

2 pyruvates

Question 13

What does glycolysis result in the production of?

Answer 13

2 pyruvates (3C) molecules
Net gain 2 ATP
2 reduced NAD

Question 14

Where does pyruvate move to?

Answer 14

When oxygen is available it will move across the double membrane of the mitochondria via active transport to enter the mitochondrial matrix.

Question 15

What is the first stage of the link reaction?

Answer 15

Pyruvate is decarboxylated- one carbon atom is removed from pyruvate in the form of CO2.

Question 16

What is the second stage of the link reaction?

Answer 16

NAD is reduced to NADH- it collects a hydrogen from pyruvate, changing pyruvate into acetate (2C) .

Question 17

What is the third stage of the link reaction?

Answer 17

Acetate is combined with coenzyme A (CoA) to form acetyl coenzyme A (acetyl CoA).

Question 18

What are the products of the link reaction for every glucose molecule?

Answer 18

Two molecules of acetyl CoA
Two molecules of CO2
Two molecules of reduced NAD

Question 19

What is the first stage in the Krebs cycle?

Answer 19

Oxaloacetate (4C) accepts the acetyl (2C) fragment from acetyl CoA to form citrate (6C).

Question 20

How is citrate regenerated into Oxaloacetate?

Answer 20

Through a series of redox reactions
Decarboxylation of citrate- release 2 CO2 as waste gas
Dehydrogenation of citrate- Releasing H atoms that reduce coenzymes NAD and FAD
8H+ 3NAD+ FAD-> 3 reduced NAD + reduced FAD
Substrate-level phosphorylation- A phosphate is transfered from one of the intermediates to ADP, forming ATP.

Question 21

What is produced by the Krebs cycle for every glucose molecule?

Answer 21

2 ATP
2 reduced FAD
6 reduced NAD
4 CO2

Question 22

Where does oxidative phosphorylation take place?

Answer 22

At the inner mitochondrial matrix

Question 23

What happens first in oxidative phosphorylation?

Answer 23

Reduced NAD and reduced FAD, from the Krebs cycle, donate hydrogen atoms.
These hydrogen atoms are split into protons (H+ ions) and electrons

Question 24

Oxidative phosphorylation: step 2: What happens to the electrons?

Answer 24

The high energy electrons enter the electron transport chain and release energy as they move through the electron transport chain.

Question 25

Oxidative phosphorylation: Step 3: What happens to the protons?

Answer 25

The released energy from the electron transport chain is used to transport (pump) protons ,though electron carriers, across the inner membrane from the matrix into the intermembrane space.

Question 26

Oxidative phosphorylation: Step 4: What happens when there is a build up of protons in the intermembrane space?

Answer 26

A (electrochemical) concentration gradient is established between the intermembrane space and the matrix.

Question 27

Oxidative phosphorylation: Step 5: What happens after the concentration gradient is estbalished?

Answer 27

The protons return to the matrix via facilitated diffusion through the channel protein ATP synthase. The movement of protons down their concentration gradient provides enough energy for ATP synthesise.

Question 28

Oxidative phosphorylation: Last step: What does oxygen do?

Answer 28

Acts as the 'final electron acceptor' and combined with protons and electrons at the end of the electron transport chain to form water. (2H + half O2= H2O)

Question 29

What happens when there is no oxygen available?

Answer 29

- There is no final acceptor of electrons from the electron transport chain - The electron transport chain stops functioning

Question 30

What type of organisms use ethanol fermentation?

Answer 30

Yeast and microorganisms

Question 31

What type of organisms use lactate fermentation?

Answer 31

Other microorganisms and mammalian muscle cells

Question 32

What is the first step in ethanol (alcoholic) fermentation?

Answer 32

Pyruvate is decarboxylated to form ethanal (this releases a CO2)

Question 33

What is the second step in ethanol (alcoholic) fermentation?

Answer 33

Ethanal accepts hydrogen (2H) from reduced NAD to form ethanol. This also makes NAD, so glycolysis can be continued.

Question 34

What is the step in lactate fermentation?

Answer 34

Pyruvate accepts the hydrogen (2H) from reduced NAD to form lactate. This also makes NAD, so glycolysis can be continued.

Question 35

What happens lactate after it is produced??

Answer 35

- It can be oxidised back to pyruvate which is then channelled into the Krebs cycle for ATP production - It can be converted to glycogen for storage in the liver

Question 36

What is the RQ value of a carbohydrate?

Answer 36

1.0

Question 37

What is the RQ value of a protein?

Answer 37

0.9

Question 38

What is the RQ value of a lipid?

Answer 38

0.7

Question 39

What is the formula to calculate the RQ value?

Answer 39

RQ= Molecules of carbon dioxide given out/ molecules of oxygen taken in

Question 40

Why can lactate fermentation be reversed?

Answer 40

- When pyruvate is reduced to lactate no atoms are lost - Because lactate dehydrogenase is available to reverse the reaction

Question 41

Why can alcoholic fermentation not be reversed?

Answer 41

- When pyruvate is converted to ethanol (two steps) and CO2, the CO2 atoms are lost- so it cannot be reversed - Decarboxylase enzyme cannot reverse the reaction.