5.2 - 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 (ETC): 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

How does pyruvate from glycolysis enter the mitochondria?

A

Via active transport

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4
Q

What happens during the link reaction?

A
  1. Oxidation of pyruvate to acetate.
    Per pyruvate molecule: net gain of 1xCO2 (decarboxylation) & 2H atoms (used to reduce 1xNAD).
  2. Acetate combines with coenzyme A (coA) to form acetylcoenzyme A.
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5
Q

Give a summary equation for the link reaction.

A

pyruvate + NAD + CoA —> acetyl CoA + reduced NAD + CO2

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6
Q

What happens in the Krebs cycle?

A

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

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7
Q

What is the electron transfer chain?

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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8
Q

What happens in the ETC?

A
  • Electron s 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 a final electron acceptor.
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9
Q

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

A
  • Some energy released from the ETC is coupled to the active transport of H+ ions (protons) from the mitochondrial matrix into the intermembrane space.
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10
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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11
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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12
Q

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

A
  • energy is released gradually
  • less energy is released as heat
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13
Q

Name 2 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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14
Q

How can lipids act as alternative respiratory substrate?

A

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

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15
Q

How can amino acids act as an alternative respiratory substrate?

A

Deamination produces:
1. 3C compunds –> pyruvate for link reaction.
2. 4C/5C compunds –> intermediates in Krebs Cycle.

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16
Q

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

A
  • Glycolysis (anaerobic)
  • Krebs cycle (aerobic)
17
Q

What happens during anaerobic respiration in animals?

A

Only glycolysis continues reduced NAD + pyruvate –> oxidised NAD (for further glycolysis) + lactate

18
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 glycogen.
19
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 ethanal using reduced NAD to produce oxidised NAD for further glycolysis.
20
Q

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

A

Converts reduced NAD back into NAD so glycolysis can continue

21
Q

What is the disadvantage of producing ethanol during anaerobic respiration?

A
  • Cells die when ethanol concentration is above 12%.
  • Ethanol dissolves cell membranes.
21
Q

What is the disadvantage of producing lactate during anaerobic respiration?

A

Acidic, so decreases pH which results in muscle fatigue.

22
Q

Similarities between anaerobic and aerobic respiration.

A
  • Both involve glycolysis
  • Both require NAD
  • Both produce ATP
23
Q

Contrast aerobic and anaerobic respiration.

A

Aerobic:
- Produces ATP by substrate-level phosphorylation and oxidative phosphorylation
- produces much more ATP
- does not produce ehtanol or lactate
Anaerobic:
- substrate-level phosphorylation only
- produces fewer ATP
- produces ethanol or lactate

24
Q

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

A
  1. Use respirometer
  2. Use a dye as a terminal electron acceptor for the ETC
25
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.

26
Q

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

A
  • Volume of O2 producd or CO2 consumed/ time x mass sample
  • Volume = distance moved by coloured drop x (0.5 x capillary tube diameter)2 x pie