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Biology A2 > 5.2 Respiration > Flashcards

5.2 Respiration Flashcards

1
Q

What is aerobic respiration?

A
  • requires oxygen and produces carbon dioxide, water and much ATP
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2
Q

What is anaerobic respiration?

A
  • does not use oxygen
  • Takes place in the absence of oxygen and produces lactate or ethanol and carbon dioxide but only a little ATP
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3
Q

What 4 stages can aerobic respiration be divided into?

A
  • Glycolysis
  • Link reaction
  • Krebs cycle
  • Oxidative Phosphorylation
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4
Q

What is glycolysis?

A
  • the first stage of respiration and the only stage in anaerobic respiration
  • the splitting of the 6 carbon glucose molecule into two 3 carbon pyruvate molecules
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5
Q

Where does glycolysis occur?

A

in the cytoplasm

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6
Q

What is glucose?

A
  • the starting substrate in glycolysis
  • an energy rich chemical
  • however, is unreactive and activation energy from ATP is needed
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7
Q

What is the first stage of glycolysis?

A
  • Phosphorylation of glucose to glucose phosphate
    >Before it can be split into 2, glucose must first be made more reactive by the addition of 2 phosphate molecules
    >The phosphate molecules come from the hydrolysis of 2 ATP molecules to ADP-this provides the energy to activate glucose and lowers the activation energy for the enzyme-controlled reactions that follow
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8
Q

What is the second stage of glycolysis?

A
  • Splitting of the phosphorylated glucose
    >each glucose molecule is split into two 3-carbon molecules known as triose phosphate
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9
Q

What is the third stage of glycolysis?

A
  • Oxidation of triose phosphate
    >hydrogen is removed from each of the two triose phosphates and transferred to a hydrogen carrier molecule known as NAD to form reduced NAD
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10
Q

What is the fourth stage of glycolysis?

A
  • The production of ATP
    >enzyme controlled reactions convert each triose phosphate into another 3-carbon-molecule called pyruvate
    >in the process, 2 molecules of ATP are regenerated from ADP
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11
Q

What is the starting substrate for glycolysis?

A

Glucose

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12
Q

What are the products for glycolysis?

A

2x pyruvate

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13
Q

How many carbon reactions are in the reactants in glycolysis?

A

6

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14
Q

How many carbons are in the products in glycolysis?

A

(2x) 3

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15
Q

Is ATP produced directly in glycolysis?

A

Yes

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16
Q

Is ATP produced via co-enzymes in Glycolysis?

A

No

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17
Q

Where does the Link Reaction take place?

A

In the matrix

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18
Q

What is the first stage of the link reaction?

A
  • the pyruvate is oxidised to acetate
    >in this reaction, the 3-carbon pyruvate loses a carbon dioxide molecule and two hydrogens
    >these hydrogens are accepted by NAD to from reduced NAD, which is later used to produce ATP
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19
Q

What is the second stage of the link reaction?

A

The 2-carbon acetate combines with a molecule called coenzyme A to produce a compound called acetylcoenzyme A

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20
Q

What is the starting substrate in the link reaction?

A

Pyruvate

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21
Q

What is the product in the link reaction?

A

Acetylcoenzyme A

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22
Q

How many carbons are in the reactants in the link reaction?

A

(x2) 3

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23
Q

How many carbons are in the products in the link reaction?

A

2

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24
Q

Is ATP produced directly in the link reaction?

A

No

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25
Q

Is ATP produced via coenzymes?

A

No

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26
Q

Where does the Krebs Cycle take place?

A

In the matrix

27
Q

What is the first stage of the Krebs Cycle?

A

The acetylcoenzyme A combines with a 4 carbon compound (oxaloacetate) to form a 6 carbon compound (citate)

28
Q

What is the second stage of the Krebs Cycle?

A

In a series of reactions citrate is converted back to oxaloacetate. The cycle itself and the chemicals involved are incidental, its the production of ATP and reduced co-enzymes NAD and FAD that’s important

29
Q

What is the third stage of the Krebs Cycle?

A

The H atoms split into protons and electrons, the protons combine with oxygen ions to form water, the electrons enter the electron transport chain

30
Q

What is the starting substrate in the Krebs Cycle?

A

Acetylcoenzyme A

31
Q

What are the products in the Krebs Cycle?

A

Carbon Dioxide
(ATP, reduced NAD, reduced FAD)

32
Q

How many carbons are in the reactants in the Krebs Cycle?

A

2

33
Q

How many carbons are in the products in the Krebs Cycle?

A

1 in each of the 2 CO2

34
Q

Is ATP produced directly in the Krebs Cycle?

A

Yes

35
Q

Is ATP produced via co-enzymes in the Krebs Cycle?

A

No

36
Q

Where does oxidative phosphorylation occur?

A

In the cristae membranes

37
Q

What is the first stage of oxidative phosphorylation?

A
  • electrons from the reduced coenzymes NAD and FAD are used to make ATP
38
Q

What is the second stage of oxidative phosphorylation?

A

The energy is used to form a proton/hydrogen ion gradient across the inner mitochondrial membrane

39
Q

What is the third stage of oxidative phosphorylation?

A

Hydrogen ions are actively transported from the matrix to the intermembrane space. The protons diffuse back through the membrane through molecules of ATPsynthase

40
Q

What is the fourth stage of oxidative phosphorylation?

A

ATP is synthesised from ADP and inorganic phosphate

41
Q

What is the fifth stage of oxidative phosphorylation?

A

Oxygen is the final electron acceptor and combines with protons and electrons to produce water

42
Q

In eukaryotic cells, what type of anaerobic respiration occur with any regualrity?

A

Pyruvate is converted to ethanol or lactate using reduced NAD. The oxidised NAD produced in the way can be used for further glycolysis

43
Q

When does anaerobic respiration occur?

A

In the absence of a ready supply of oxygen (e.g. during intense physical activity, when oxygen reserves are depleted)

44
Q

How do you generate small amounts of energy in anaerobic respiration?

A

In order to generate the small amounts of energy provided by glycolysis, the end product must be converted into another substance before more glucose can be used

45
Q

Why must pyruvate be converted into another substance before more glucose can be used?

A

Because the conversion of pyruvate replenishes the levels of the hydrogen acceptor (NAD) needed for glycolysis to occur

46
Q

What happens to the reduced NAD in anaerobic respiration?

A
  • glycolysis produces 2 reduced NAD molecules
  • In aerobic respiration these are used in oxidative phosphorylation to generate ATP
  • No oxidative phosphorylation in anaerobic respiration
  • NAD must be regenerated
47
Q

What process converts pyruvate into ethanol?

A

fermentation

48
Q

What is the equation of fermentation?

A

pyruvate + reduced NAD -> ethanol + carbon dioxide + NAD

49
Q

In muscle cells when does anaerobic respiration happen?

A

occurs when there is a temporary shortage of oxygen

50
Q

What is the equation of muscle cells?

A

Pyruvate + 2 reduced NAD -> lactate + 2 NAD

51
Q

How does pyruvate from glycolysis enter the mitochondria?

A

via active transport

52
Q

What is the electron transport chain?

A

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

53
Q

What happens in the electron transfer chain?

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 final electron acceptor

54
Q

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

A

some energy released from the ETC is coupled to the active transport of H+ ions from the mitochondrial matrix into the intermembrane space

55
Q

How does chemiosmosis produce ATP during aerobic respiration?

A

H+ ions move down their concentration gradient from the intermembrane space into the mitochondrial matrix via the channel protein ATP synthase

56
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
57
Q

Name 2 types of molecules that can be used as alternative respiratory substances

A
  • amino acids from proteins
  • glycerol and fatty acids from lipids
58
Q

How can lipids act as an alternative respiratory substrate?

A
  1. Phosphorylation of glycerol -> TP for glycolysis
  2. Fatty acid -> acetate
    a) acetate enters link reaction
    b) H atoms produced for oxidative phosphorylation
59
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
60
Q

What happens during anaerobic respiration in some microorganisms?

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
61
Q

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

A

converts reduced NAD back into NAD so glycolysis can continue

62
Q

What is the disadvantage of producing ethanol during anaerobic respiration?

A
  • cells die when ethanol concentration is above 12%
  • ethnaol dissolves cell membranes
63
Q

What is the disadvantage of producing lactate during anaerobic respiration?

A
  • acidic, so decreases pH
  • results in muscle fatigue

Biology A2 (19 decks)

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