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BIO 3.5 - energy transfers in and between organisms > respiration > Flashcards

respiration Flashcards

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1
Q

Name the 4 main stages in aerobic respiration and where they occur.

A

Glycolysis: cytoplasm.
Link reaction: mitochondrial matrix.
Krebs cycle: mitochondrial matrix.
Oxidative phosphorylation via electron transfer chain: membrane of cristae.

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2
Q

Outline the stages of glycolysis.

A
  1. glucose is phosphorylated to glucose phosphate by 2x ATP.
  2. glucose phosphate splits into 2x triose phosphate (TP).
  3. 2x TP is oxidised to 2x pyruvate.

Net gain of 2x reduced NAD & 2x ATP per glucose.

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3
Q

Draw a flowchart to represent what happens during glycolysis.

A

(see notes)

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4
Q

How does pyruvate from glycolysis enter the mitochondria?

A

via active transport.

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5
Q

What happens during the link reaction?

A
  1. oxidation of pyruvate to acetate.
    Per pyruvate molecule: net gain of 1x CO2 (decarboxylation) & 2H atoms (used to reduce 1x NAD).
  2. acetate combines with coenzyme A (CoA) to form Acetylcoenzyme A.
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6
Q

Give a summary equation for the link reaction.

A

pyruvate + NAD + CoA
Acetyl CoA + reduced NAD + CO2.

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7
Q

What happens in the Krebs cycle?

A

series of redox reactions produces:
ATP by substrate-level phosphorylation.
Reduced co-enzymes.
CO2 from decarboxylation.

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8
Q

Outline the stages of the Krebs cycle (draw a diagram).

A

(see notes)

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9
Q

What is the electron transfer chain (ETC)?

A

Series of carrier proteins embedded in membrane of the cristae of mitochondria.
Produces ATP through oxidative phosphorylation via chemiosmosis during aerobic respiration.

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10
Q

What happens in the electron transfer chain (ETC)?

A

Electrons released from reduced NAD & FAD undergo successive redox reactions.
The energy released is coupled to maintaining proton gradient or released as heat.
Oxygen acts as final electron acceptor.

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11
Q

How is a proton concentration gradient established during chemiosmosis in aerobic respiration?

A

Some energy released from ETC is coupled to the active transport of H+ ions (protons) from the mitochondrial matrix into the intermembrane space.

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12
Q

How does chemiosmosis produce ATP during aerobic respiration?

A

H+ ions (protons) move down their concentration gradient from the intermembrane space into the mitochondrial matrix via the channel protein ATP synthase.
ATP synthase catalyses ADP + Pi - ATP.

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13
Q

State the role of oxygen in aerobic respiration.

A

Final electron acceptor in electron transfer chain.
(produces water as a byproduct).

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14
Q

What is the benefit of an electron transfer chain rather than a single reaction?

A

Energy is released gradually.
Less energy is released as heat.

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15
Q

Name two types of molecule that can be used as alternative respiratory substrates.

A

(amino acids from) proteins.
(glycerol and fatty acids from) lipids.

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16
Q

How can lipids act as an alternative respiratory substrate?

A

lipid - glycerol + fatty acids.
1. Phosphorylation of glycerol - TP for glycolysis.
2. Fatty acids - acetate.
a) acetate enters link reaction.
b) H atoms produced for oxidative phosphorylation.

17
Q

How can amino acids act as an alternative respiratory substrate?

A

Deamination produces:
1. 3C compounds - pyruvate for link reaction.
2. 4C / 5C compounds - intermediates in Krebs cycle.

18
Q

Name the stages in respiration that produce ATP by substrate-level phosphorylation.

A

Glycolysis (anaerobic).
Krebs cycle (aerobic).

19
Q

What happens during anaerobic respiration in animals?

A

Only glycolysis continues.
Reduced NAD + pyruvate - oxidised (for further glycolysis) + lactate.

20
Q

What happens to the lactate produced in anaerobic respiration?

A

Transported to liver via bloodstream, where it is oxidised to pyruvate.
Can enter link reaction in liver cells or be converted to glycolysis.

21
Q

What happens during anaerobic respiration in some microorganisms e.g. yeast and some plant cells?

A

Only glycolysis continues.
Pyruvate is decarboxylated to form ethanal.
Ethanal is reduced to ethanol using reduced NAD to produce oxidised NAD for further glycolysis.

22
Q

Draw a flowchart to show how ethanol is produced during anaerobic respiration.

A

(see notes)

23
Q

What is the advantage of producing ethanol / lactate during anaerobic respiration?

A

Converts reduced NAD back into NAD so glycolysis can continue.

24
Q

What is the disadvantage of producing ethanol during anaerobic respiration?

A

Cells die when ethanol concentration is above 12%.
Ethanol dissolves cell membranes.

25
Q

What is the disadvantage of producing lactate during anaerobic respiration?

A

Acidic, so decreases pH.
Results in muscle fatigue.

26
Q

Compare aerobic and anaerobic respiration.

A

Both involve glycolysis.
Both require NAD.
Both produce ATP.

27
Q

Contrast aerobic and anaerobic respiration.

A

Aerobic:
Produces ATP by substrate-level phosphorylation AND oxidative phosphorylation.
Produces much more ATP.
Does not produce ethanol or lactate.
Anaerobic:
Substrate-level phosphorylation only.
Produces fewer ATP.
Produces ethanol or lactate.

28
Q

Suggest how a student could investigate the effect of a named variable on the rate if respiration of a single-celled organism.

A
  1. Use respirometer (pressure changes in boiling tube cause a drop of coloured liquid to move).
  2. Use a dye as the terminal electron acceptor for the ETC.
29
Q

What is the purpose of sodium hydroxide solution in a respirometer set up to measure the rate of aerobic respiration?

A

Absorbs CO2 so that there is a net decrease in pressure as O2 is consumed.

30
Q

How could a student calculate the rate of respiration using a respirometer?

A

Volume of O2 produced or CO2 consumed / time X mass of sample.
Volume = distance moved by coloured drop X (0.5 X capillary tube diameter)^2 X pi

BIO 3.5 - energy transfers in and between organisms (4 decks)

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