4.4 Respiration

Question 0

What does dehydrogenated mean?

Answer 0

Hydrogen is removed.

Question 1

What is phosphorylation?

Answer 1

The addition of a phosphate group.

Question 2

What is decarboxylation?

Answer 2

CO2 is removed.

Question 3

What are NAD and FAD?

Answer 3

They are co-enzymes that can carry Hydrogen.

Question 4

What is Co-Enzyme A?

Answer 4

A co-enzyme that can carry an acetyl (2C) group.

Question 5

What is oxidation?

Answer 5

Addition of oxygen/ Removal of hydrogen/ Loss of electron

Question 6

What is reduction?

Answer 6

Removal of oxygen/ addition of hydrogen/ gain of electrons.

Question 7

Equation for: aerobic respiration?

Answer 7

Glucose + Oxygen ▶️ Carbon Dioxide + Water + Energy

C6H12O6 + 6(O2) ▶️ 6(CO2) + 6(H2O) + (~38 ATP)

Question 8

Equation for: anaerobic respiration in Animals

Answer 8

Glucose ▶️ Lactate + Energy

C6H12O6▶️ C3H6O3 + (2 ATP)

Question 9

Equation for: anaerobic respiration in Yeast?

Answer 9

Glucose ▶️ Ethanol + Carbon Dioxide + Energy

C6H12O6 ▶️ C2H5OH + 2(CO2) + (2 ATP)

Question 10

List some functions of ATP.

Answer 10

Active transport
Synthesis reactions
Muscle contraction
Cell division
Light independent reactions
First stage of glycolysis

Question 11

Describe glycolysis.

Answer 11

Glucose is converted into 2 Triose Phosphate molecules (3C) where 2 ATP molecules are used to phosphorylate glucose.

Triose Phosphate is then converted to Pyruvate (3C). The oxidation of TP to Py releases ATP under a process known as SUBSTRATE LEVEL PHOSPHORYLATION. 4 ATP molecules are produced for every glucose oxidised.

The oxidation of TP leaves hydrogen to be accepted by NAD to form NADH (reduced NAD).

Question 12

Where does glycolysis occur?

Answer 12

The cytoplasm of the cell.

Question 13

Where does the Link reaction and Krebs cycle occur?

Answer 13

In the matrix of the mitochondrion.

Question 14

Where does Oxidative Phosphorylation occur?

Answer 14

In the cristae (folds of inner membrane) of the mitochondrion.

Question 15

Describe the Link reaction.

Answer 15

Pyruvate is oxidised by the removal of hydrogen atoms and CO2 is removed. At the same time Co-Enzyme A is added to Acetyl to form Acetyl Coenzyme A.
Two hydrogen atoms are accepted by NAD to form NADH2.

Question 16

Describe the Krebs Cycle.

Answer 16

Known as a series of oxidation reduction reactions.
Acetyl Coenzyme A will combine with a 4C acceptor molecule which will regenerate the co enzyme and a 6C molecule.
A series of decarboxylation reactions occur to regenerate the 4C acceptor molecule. The carbon is lost as CO2.

Enough energy is released at one step to produce an ATP molecule. (SLP)

Oxidation/ removal of hydrogen atoms occurs and these atoms are passed to NAD and FAD to form NADH2 and FADH2 (reduced nad and fad)

The hydrogen atoms will be used in the electron transport chain.

Question 17

What are the two main methods of producing ATP in aerobic respiration?

Answer 17

Substrate Level Phosphorylation

Oxidative Phosphorylation (electron transport chain)

Question 18

True or false: Oxidative phosphorylation can occur under anaerobic conditions.

Answer 18

False; it can only occur in aerobic.

Question 19

Why do we need oxygen in Oxidative Phosphorylation?

Answer 19

It is the terminal electron acceptor so that ATP can be produced.

Without it, the electron transport chain wouldnt function, aerobic respiration would stop and no ATP would be produced.

Question 20

Describe oxidative phosphorylation/electron transport chain.

Answer 20

Reduced NAD and FAD are oxidised- their hydrogen atoms are released to the first carrier of the electron transport chain. Each hydrogen is split into an electron and a proton (H+).

Electrons pass down carriers at decreasing energy levels. Energy is released as electrons are transferred. This energy is used to actively transport protons across the inner mitochondrial membrane to the inter membrane space.

A proton gradient is established. This means protons diffuse across the inner membrane into the matrix via ATP synthase.

The movement of protons releases energy which is used to form ATP from ADP+Pi.

At the end of the chain electrons combine with protons and oxygen to make water.

Question 21

What steps does Anaerobic respiration do? Why does it not take the other remaining steps?

Answer 21

Glycolysis and production of pyruvate.

The other reactions do not occur as pyruvate stays in the cytoplasm and no more ATP is produced except for the net 2ATP (per glucose) in glycolysis.

Question 22

What happens to NAD in anaerobic respiration?

Answer 22

Pyruvate is reduced using reduced NAD from glycolysis. This enables NAD to regenerate.
This ensures continuous supplies of NAD for glycolysis.

Question 23

Why is the regeneration of NAD so important?

Answer 23

If NAD was not regenerated, glycolysis would eventually stop as all NAD would be reduced and no NAD would be avaliable for Triose Phosphate to be oxidised into Pyruvate.

Question 24

What is a respirometer?

Answer 24

A device used to measure the rate of respiration of a living organism by measuring its uptake of oxygen or release of carbon dioxide.

Question 25

How does a respirometer work?

Answer 25

When organisms respire aerobically, oxygen is absorbed. CO2 is absorbed by KOH.
This means the volume inside the respirometer decreases therefore the pressure decreases and the bubble moves to the left.

This tells us that any movement is due to the absorption of oxygen.

Question 26

How do we calculate rate of oxygen consumption?

Answer 26

We will need:
Distance bubble moves
Radius of the tube (allows conversion of distance moved to volume)
Time (rate calculation)

Question 27

How do we measure rate of CO2 production?

Answer 27

Same as oxygen production experiment yet we remove the KOH.