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Y13 Biology > Topic 5 A: Respiration > Flashcards

Topic 5 A: Respiration Flashcards

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1
Q

When is ATP broken down?

A

The breakdown of ATP, from glucose, occurs during respiration.

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2
Q

Glycolysis simple summary?

A
  • splits one molecule of glucose into smaller molecules of pyruvate
  • doesn’t require oxygen - its an anaerobic process
  • takes place in cytoplasm of cells because glucose cannot cross the outer mitochondrial membrane
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3
Q

Stage one of glycolysis?

A

Phosphorylation of glucose:
- 2 phosphate molecules added to glucose to form fructose biphosphate (or glucose phosphate), which is unstable.
- 2 ATP molecules hydrolysed to allow this to occur.

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4
Q

Stage two of glycolysis?

A

Production of triosephsophate:
- splitting occurs because glucose phosphate is unstable ( due to 6C) into 2 triosephosphate molecules with 3C and 1 phosphate.

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5
Q

Stage three of glycolysis?

A

Oxidation of triosephosphate:
- one NAD (coenzyme) gains hydrogen from each TP molecule (2 in total)
- TP is oxidised (lost hydrogen) and NAD is reduced (NADH+)
- (2) pyruvate molecules created

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6
Q

Final products of glycolysis?

A
  • 2 pyruvate
  • 2 NADH
  • 2 ATP (net gain - used 2 at the beginning)
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7
Q

Exam question : Describe the process of glycolysis? (4)

A
  1. phosphorylation of glucose occurs using ATP
  2. splits into 2 TP and is oxidised to form pyruvate
  3. NADH created
  4. net gain of 2 ATP
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8
Q

How does pyruvate reach the link reaction?

A

Actively transported into mitochondrial matrix for this stage (using transport protein)

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9
Q

Overall function of the link reaction?

A

Converts 2 pyruvate molecules into acetyl co-enzyme A (acetyl Co-A)

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10
Q

Overall equation of the link reaction?

A

pyruvate + NAD + CoA = acetyl Co-A + reduced NAD + CO2

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11
Q

Link reaction process?

A
  1. pyruvate oxidised (lost H) into acetate, H lost is picked up by NAD x2 (reduced)
    (the loss of hydrogen is known as dehydrogenation)
  2. pyruvate is a 3C molecule, acetate is 2C. Pyruvate loses one C in form of CO2 (decarboxylation)
  3. acetate converts into acetyl Co-A by reacting with co enzyme A
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12
Q

Krebs cycle process - Part one - The creation of citrate

A
  1. acetyl CoA comes from link reaction
  2. acetyl CoA reacts with oxaloacetate to create six-carbon citrate
  3. citrate then converted back into oxaloacetate through series of small reactions, cycle repeats
  4. CoA back into link reaction after citrate is formed
    - the purpose of acetyl CoA is to bring acetate into the krebs cycle
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13
Q

Krebs cycle process - Part two - Formation of 5 carbon compound

A
  1. citrate converted into 5C compound
  2. this happens because decarboxylation (loss of CO2) and dehydrogenation occurs (NAD to NADH)
  3. intermediate compound (5C) formed.
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14
Q

Krebs cycle process - Part three - Regeneration of 4 carbon compound

A
  1. decarboxylation and dehydrogenation of intermediate compound occurs
  2. one molecule of reduced FAD is produced from FAD
  3. two molecules of reduced NAD is produced from NAD
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15
Q

Krebs cycle process - Part four - Production of ATP

A
  1. produced by the direct transfer of a phosphate group
  2. direct transfer known as substrate-level phosphorylation
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16
Q

Products of the krebs cycle?

A
  • 1 CoA
  • 1 oxaloacetate
  • 2 CO2
  • 1 ATP
  • 3 reduced NAD
  • 1 reduced FAD
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17
Q

Where does oxidative phosphorylation take place?

A
  • in the cristae
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18
Q

Oxidative phsophorylation simple definition?

A
  • when energy carried by electrons and reduced co-enzymes (NAD and FAD) are used to make ATP
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19
Q

Part one of oxidative phosphorylation?

A
  • reduced NAD and FAD lose hydrogen atoms (oxidised)
  • hydrogen atoms split into protons (H+) and electrons (e-)
20
Q

Part two of oxidative phosphorylation?

A
  • electrons are embedded within the inner membrane
  • they then pass along electron transfer chain, and every time an electron moves to the next protein, it releases enough energy to transport a proton to the inner membrane space
  • this occurs via active transport
  • the movement of H+ ions from low to high creates electrochemical gradient
21
Q

Part three of oxidative phosphorylation?

A
  • protons move back down the electrochemical gradient from inner membrane to the matrix via ATP synthase.
  • this occurs through facilitated diffusion
  • this drives ATP synthesis (ADP+Pi)
22
Q

Why is this process described as being oxidative?

A
  • protons + electrons + oxygen = water
  • oxygen = final electron acceptor
23
Q

What would happen if oxygen wasn’t present?

A
  • reduced co-enzymes cannot be oxidised to regenerate NAD and FAD
  • protons wouldnt be transported across the membrane and no electrochemical gradient will form
  • no more electrons would be able to move down the chain
  • ATP not synthesised
24
Q

ATP reference point for aerobic respiration processes?

A
  • 2.5 ATP made from each reduced NAD
  • 1.5 ATP made from each reduced FAD
25
Q

How much ATP made during glycolysis?

A

product = 2 ATP & 2 NADH
- 7 ATP

26
Q

How much ATP made during link reaction?

A

product = 2 NADH
- 5 ATP

27
Q

How much ATP made during krebs cycle?

A

product = 2 ATP & 6 NADH & 2 FADH
- 20 ATP

28
Q

How much ATP made during oxidative phosphorylation?

A
  • 28 ATP
29
Q

Total molecules of ATP within aerobic respiration?

A
  • around 32
30
Q

What else can be used as respiratory substances?

A

Lipids and proteins.

31
Q

Hydrolysis if lipids and proteins?

A

lipids = glycerol and fatty acids
proteins = amino acids

32
Q

Energy of lipids compared to glucose?

A

lipids release more than double the amount of energy than glucose.

33
Q

Respiration and lipids?

A
  • fatty acids are broken down into acetyl coA which enters krebs cycle
  • glycerol is phosphorylated and then converted into triose phosphate, then enters through glycolysis into krebs cycle.
34
Q

Respiration and proteins?

A
  • amino acid group is removed, this is called deamination, 3C compounds converted into pyruvate.
  • four and five carbon compounds converted to immediate compounds.
35
Q

Where does anaerobic respiration occur?

A
  • in the cytoplasm
36
Q

Steps of anaerobic respiration?

A
  1. glycolysis
  2. fermentation (yeast or lactate)
37
Q

Main purpose of anaerobic respiration?

A
  • to release small amounts of ATP and to oxidise NAD
  • this is crucial because we have to ensure the NAD can be reused in glycolysis again
38
Q

Total energy formed in anaerobic respiration?

A

2 ATP

39
Q
  1. Ethanol fermentation process?
A
  1. glycolysis (glucose into pyruvate)
  2. pyruvate loses CO2 (decarboxylation)
  3. reduced NAD (from glycolysis) transfers hydrogen to ethanal to form ethanol.
  4. ethanal is reduced to ethanol by enzyme, alcohol dehydrogenase
    - ethanal is the final hydrogen acceptor
40
Q

Ethanol fermentation equation?

A

pyruvate + reduced NAD = ethanol + CO2 + oxidised NAD

41
Q
  1. Lactate fermentation process?
A
  1. glycolysis (glucose to pyruvate)
  2. reduced NAD (from glycolysis) transfers hydrogen to pyruvate to from lactate
  3. pyruvate is reduced to lactate by the enzyme lactate dehydrogenase
    - pyruvate is the final hydrogen acceptor
42
Q

Lactate fermentation equation?

A

pyruvate + reduced NAD = lactate + oxidised NAD

43
Q

What happens to the lactate after?

A
  • further metabolised back into pyruvate or converted into glycogen
44
Q

Exam question: Malonate inhibits a reaction in the Krebs cycle.
Explain why malonate would decrease the uptake of oxygen in a respiring
cell.

A
  1. less coenzymes / fewer electrons removed
  2. oxygen is final electron acceptor
45
Q

Exam question: In muscles, pyruvate is converted to lactate during prolonged exercise.
Explain why converting pyruvate to lactate allows the continued production
of ATP by anaerobic respiration.

A
  1. oxidises reduced NAD
  2. so glycolysis continues

Y13 Biology (11 decks)

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