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Biology pt2 > 5.2 Respiration > Flashcards

5.2 Respiration Flashcards

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1
Q

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

A
  • Glycolysis: cytoplasm
  • Link reaction: mitochondria matrix
  • Krebs cycle: mitochondrial matrix
  • Oxidative phosphorylation - via electron transfer chain: membrane of cristae
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2
Q

Outline stages of glycolysis

A
  1. Glucose is phosphorylated into 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 and 2x ATP per glucose

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3
Q

Flowchart of what happens during glycolysis

A
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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
  2. Acetate combines with coenzyme A (CoA) to form acetylcoenzyme A
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6
Q

Give 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 conenzymes
- CO2 from decarboxylation

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8
Q

Outline the stages of the Krebs cycle

A

NB: the 6C compound is citrate

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9
Q

Process of Krebs cycle

A
  1. Acetyl CoA combines with a 4 carbon molecule to form a 6C molecule
  2. The 6C molecule is oxidised into a 5C molecule using NAD+. Decarboxylation happens
  3. The 5C molecule is oxidised into a 4c molecule using FAD+. Decarboxylation occurs
  4. ATP is also generated
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10
Q

What is the electron transfer chain (ETC)?

A
  • Series of carrier proteins embedded in membrane of cristae of mitochondria
  • Produces ATP through oxidative phosphorylation via chemiosmosis during aerobic respiration
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11
Q

What happens in the electron transfer chain (ETC)?

A
  • Electrons released from reduced NAD and 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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12
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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13
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 ATP synthase

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14
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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15
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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16
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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17
Q

How can lipids act as an alternative respiratory substrate?

A
  • Lipid –> glycerol + fatty acids
  1. Phosphorylation of glycerol –> TP for glycosis
  2. Fatty acid –> acetate
    a) Acetate enters link reaction
    b) H atoms produced for oxidative phosphorylation
18
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

19
Q

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

A
  • Glycolysis (anaerobic)
  • Krebs cycle (aerobic)
20
Q

Stages 1 of oxidative phosphorylation (reduction)

A
  • NADH or FADH2 is oxidised into NAD+ OR FAD+.
  • This releases a proton into the matrix and 2e- are transferred to the first carrier protein
  • The energy from these electrons allow the first carrier protein to pump a proton into the intermembrane space
21
Q

Stage 2 of oxidative phosphorylation (oxidation + reduction)

A
  • The electrons are lost from the first carrier protein (oxidation) and transported to the second carrier protein (reduction)
  • This provides energy to pump another proton
22
Q

Stage 3 of oxidative phosphorylation

A
  • The electrons are lost from the second carrier protein (oxidation) and transported to the third carrier protein (reduction).
  • This provides energy to pump another proton
23
Q

Stage 4 of oxidative phosphorylation (electrochemical gradient)

A
  • The protons in the intermembrane space form an electrochemical gradient
  • They diffuse through ATP synthase to allow catalysis of ADP + Pi –> ATP
24
Q

Stage 5 of oxidative phosphorylation

A

The 2 electrons combine with 1/2 O2 - the final electron acceptor - in the matrix which reacts with 2H+ to make H2O

25
Q

How is the role of oxygen in oxidative phosphorylation critical?

A

In its absence, the electron transport chain and the transport of hydrogen would grind to a halt

26
Q

Describe how ATP is made in the mitochondria

A
  1. ATP produced in Krebs cycle
  2. Krebs cycle/ link reaction produces reduced NAD/FAD
  3. Electrons released from reduced coenzymes
  4. Electrons pass along carriers, through electron transport chain through a series of redox reactions
  5. Energy is released
  6. Protons move into intermembrane space
27
Q

What happens during anaerobic respiration in animals?

A
  • Only glycolysis continues
  • reduced NAD + pyruvate –> oxidised NAD (for further glycolysis) + lactate
27
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
28
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
29
Q

Advantage of producing ethanol/lactate during anaerobic respiration?

A

Converts reduced NAD back into NAD so glycolysis can continue

30
Q

Disadvantage of producing ethanol during anaerobic respiration?

A
  • Cells die when ethanol concentration is about 12%
  • Ethanol dissolves cell membranes
31
Q

Disadvantage of producing lactate during anaerobic respiration?

A
  • Acidic, so decreases pH
  • Results in muscle fatigue
  • Denatures cellular proteins
  • Must be oxidised in liver using oxygen debt
32
Q

Process of anaerobic respiration

A
  • Absence of oxygen final electron acceptor
  • Oxidative phosphorylation stops
  • NAD+ and FAD+ cannot be resynthesised (stuck in NADH/FADH2 form)
  • Krebs cycle and link reaction stops due to lack of NAD+ and FAD+
  • Cell relies on anaerobic respiration of pyruvate
33
Q

Anaerobic respiration in animals

A
  1. Pyruvate is reduced into lactate using NADH
  2. NAD+ is resynthesised
  3. NAD+ is used to allow the triose phosphate to pyruvate step of glycolysis to take place - generating ATP
33
Q

Anaerobic respiration in yeast

A
  1. Pyruvate is reduced into ethanol using NADH
  2. Decarboxylation occurs
  3. NAD+ is resynthesised
  4. NAD+ is used to allow the triose phosphate to pyruvate step of glycolysis to take place - generating ATP
34
Q

Compare aerobic and anaerobic respiration

A
  • Both require glycolysis
  • Both require NAD
  • Both produce ATP
35
Q

Contrast aerobic and anaerobic respiration

A
  1. Aerobic produces ATP by substrate-level phosphorylation AND oxidative phosphorylation, anaerobic substrate level phosphorylation only
  2. Aerobic produces more ATP, anaerobic produces less ATP
  3. Aerobic does not produce ethanol or lactate, anaerobic produces ethanol or lactate
36
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 a 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
37
Q

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

38
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 3.14

Biology pt2 (33 decks)

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