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OCR A-level Biology > Respiration > Flashcards

Flashcards in Respiration Deck (40)
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1

Why does respiration occur?

To produce ATP for energy

Required in metabolic processes and for the organism to survive

2

Give examples of biological processes where ATP is required

Active Transport
Endocytosis
Exocytosis
Protein synthesis
DNA Replication
Cell division
Movement
Anabolic and Catabolic reactions

3

Describe the structure of ATP

Pentose sugar (Ribose)
Adenine base
3 phosphates joined to sugar by phosphodiester bond

4

Describe the process of Glycolysis

Phosphorylation of Glucose to Hexose biphosphate

Lysis of Hexose biphosphate to Triose phosphate

Oxidation of Triose phosphate to Pyruvate

5

What are the 4 stages of aerobic respiration?

Glycolysis
Link Reaction
Krebs Cycle
Oxidative Phosphorylation

6

What are the products of Glycolysis?

2 ATP (4 were made by 2 were used at start)
2 reduced NAD (NADH)
2 Pyruvate

7

In What organelle does respiration occur?

Mitochondrion

8

Outline the key structures in the mitochondria

Double membrane (inter-membrane space)
Matrix
Cristae
ATP Synthase channels

9

What does the matrix contain?

Enzymes
NAD and FAD molecules
Oxaloacetate
mitochondrial DNA
mitochondrial ribosomes

10

Why is the inner membrane folded into cristae?

To provide a large surface area for the electron carriers and ATP synthase enzymes

11

Where does the link reaction occur?

Mitochondrial matrix

12

What enzyme catalyses the link reaction?

Pyruvate dehydrogenase

13

What is the main products of the link reaction?

Acetyl CoA and NADH

14

What is the bi-product of the Link reaction

CO2

15

How many molecules of each product are formed per 1 molecule of pyruvate in the link reaction?

1 Acetyl CoA
1 NADH
1 CO2

16

Where does the Krebs cycle occur?

Mitochondrial matrix

17

What is substrate-level phosphorylation?

the formation of ATP from ADP by donation of a phosphate from a substrate.

Low yield of ATP

18

Outline the main stages of the Krebs cycle

Acetyl (2C) group released from Acetyl CoA and combines with Oxaloacetate (4C) to form Citrate (6C)

2 stages of oxidative (aka dehydrogenation) decarboxylation occur forming a 4C compound releasing 2CO2 and 2 NADH

4C compound further dehydrogenated releasing FADH

4C compound is rearranged by isomerase enzymes and dehydrogenated (releasing NADH) to form oxaloacetate

19

What is the Krebs cycle designed to make lots of?

NADH (reduced NAD)

20

Outline the process by which energy is produced from the ETC

NADH releases a H atom, this then splits into H+ and e-

H+ accumulate in the matrix

e- picked up by a carrier protein which causes it to become reduced and pass it on to the next carrier protein in the chain (series of redox reactions)

at the end of the chain:
4H+ + 4e- + O2 = 2H2O

21

How is the energy released from the ETC used to create ATP?

the energy released is used to actively transport the H+ from the matrix into the inter-membrane (IM) space

H+ accumulate in IM space (as the membrane is impermeable to H+) forming an electrochemical gradient.

H+ move back through protein channels coupled to ATP Synthase enzymes

Causes a conformational change in ATP Synthase driving the production of ATP

22

Where does oxidative phosphorylation occur?

Cristae

23

Why will the process of oxidative phosphorylation not occur in anaerobic conditions?

No O2 as final acceptor of ETC
Build up of e- in the matrix
Electrochemical gradient doesn't form
ATP Synthase isn't activated
No ATP produced

24

Why must NADH be reoxidised for respiration to continue?

Because it is needed for the link reaction and Krebs cycle to occur

25

What are the 2 anaerobic pathways to reoxidise NADH?

Ethanol fermentation
Lactate fermentation

26

What organisms use alcohol fermentation?

Fungi such as yeast

27

What organisms use lactate fermentaion?

Mammals

28

Outline the stages of ethanol fermentation?

Pyruvate is decarboxylated to form Ethanal + CO2

Ethanal accepts H+ from NADH which reduces it to Ethanol + NAD

This means the NADH has been reoxidised allowing glycolysis to continue.

29

What enzyme catalyses Pyruvate to Ethanal?

Pyruvate Decarboxylase

30

What enzyme catalyses Ethanal to Ethanol?

Ethanol Dehydrogenase

31

Outline the Lactate fermentation pathway

Pyruvate accepts H+ from NADH, reducing it to lactate

This means the NADH has been reoxidised allowing glycolysis to continue.

32

What happens to the lactate molecules when they are produced?

Transported to the liver

When more O2 becomes available it is:

Converted back to pyruvate
Recycled into glucose and glycogen

33

Describe the yield of ATP from anaerobic respiration compared to aerobic respiration

Neither ethanol nor lactate fermentation produce any ATP

However, they allow glycolysis to continue which means a small amount of ATP per molecule is still made

Glycolysis happens a lot more frequently in anaerobic respiration than aerobic respiration so the yield of ATP is still high.

34

How are different carbohydrates converted to glucose for respiration?

Disaccharides are hydrolysed into monosaccharides

Monosaccharides such as fructose and galactose are rearranged by isomerase enzymes

35

Why do lipids have a higher energy value than other respiratory substrates?

Because the long fatty acid chains contain lots of hydrogens that can be snipped off at any length.

The are broken down into Acetate (2C) which combines with CoA in the link reaction

more h+ = more energy

36

What is the name of the process where excess amino acids are converted to pyruvate?

Deamniation

37

Where does Deamination occur?

Kidneys

38

What is the equation for respiratory quotient?

RQ = CO2 produced / O2 consumed

39

What are the RQ values for the different respiratory substrates?

Glucose = 1
Fatty acid = 0.7
Amino acid= 0.8 - 0.9

40

What would a respiratory quotient value of >1 indicate?

Aerobic respiration

because the amount of CO2 produced is greater than O2 consumed.