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Biology OCR A A level > Respiration > Flashcards

Respiration Flashcards

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1
Q

What are the 4 stages of respiration?

A

Glycolysis
Link Reaction
Krebs Cycle
Electron Transport Chain

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2
Q

Where does glycolysis occur in the cell?

A

Cell cytoplasm

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3
Q

Which coenzyme/s are involved in glycolysis?

A

NAD+

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4
Q

What is the role of NAD+ in glycolysis?

A

Transferring of electrons between molecules

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5
Q

What are the four steps of glycolysis?

A

Phosphorylating glucose
Splitting phosphorylated glucose
Phosphorylation (second)
Oxidation to pyruvate

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6
Q

Explain the process of phosphorylation of glucose

A

2 ATPs hydrolysed into 2ADP + 2Pi provide the phosphates for a molecule of glucose (6C) to be converted into hexose bisphosphate (6C)

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7
Q

What is the point of phosphorylating glucose?

A

Makes it more reactive

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8
Q

Explain what happens in the lysis stage of glycolysis

A

Hexose bisphosphate is converted into two molecules of triose phosphate (3C)

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9
Q

What are triose phosphate molecules phosphorylated to?

A

Two triose bisphosphate molecules with the phosphate coming from free ions in the cytoplasm

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10
Q

Explain how triose bisphosphate molecules are oxidised to pyruvate

A

Two molecules of triose bisphosphate are oxidised to pyruvate
NAD+ ions accept the removed hydrogen ions to form r NADH
ATP is reduced by substrate level phosphorylation

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11
Q

Explain what substrate level phosphorylation is

A

The formation of ATP without he use of an electron transport chain

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12
Q

What is the net overall yield of ATP in glycolysis?

A

2 molecules of ATP

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13
Q

Is glycolysis aerobic or anaerobic?

A

Aerobic

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14
Q

Where does the link reaction occur?

A

Mitochondrial Matrix

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15
Q

How does pyruvate reach the mitochondrial matrix for the link reaction?

A

Actively transported from the cytoplasm via carrier proteins

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16
Q

Explain what occurs during the link reaction

A

Decarboxylation of pyruvate to release carbon dioxide
Pyruvate is oxidised
NAD+ into NADH
A molecule of acetyl Coenzyme A is produced

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17
Q

What is the name of the process of the link reaction?

A

Oxidative Carboxylation

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18
Q

Where does the NADH produced in the link reaction go?

A

Used in oxidative phosphorylation to synthesise ATP

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19
Q

What happens to the waste carbon dioxide produced in the link reaction?

A

Diffuse away
Removed as metabolic waste
Used as raw material in photosynthesis

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20
Q

Where does the Krebs Cycle take place?

A

The mitochondrial matrix

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21
Q

What two coenzymes does the Krebs Cycle involve?

A

NAD+ and FAD

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22
Q

Explain step 1 of the Krebs cycle

A

Acetyl CoA (2C) joins with oxaloacetate (4C) to form citrate (6C)

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23
Q

Explain step 2 of the Krebs cycle

A

Decarboxylation of citrate resulting in removal of carbon dioxide
Hydrogen removed from citrate which reduces NAD+
A five carbon compound is formed

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24
Q

Explain step 3 of the Krebs Cycle

A

Further decarboxylation and dehyradation to produce a 4 carbon compound
NAD+ is reduced to NADH
ATP produced via substrate level phosphorylation

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25
Q

Explain step 4 of the Krebs Cycle (regeneration)

A

Regeneration of oxaloacetate
FAD reduced to FADH2
NAD+ reduced to NADH

26
Q

Where does oxidative phosphorylation take place?

A

In the cristae/inner membrane of the mitochondria

27
Q

What is the role of NADH and FADH2 in respiration?

A

Carry H atoms to the electron transport chain where they dissociate into H+ ions and e-
Electrons are passed down electron transport chain

28
Q

What type of reaction occurs in the electron transport chain?

A

Redox

29
Q

What happens when electrons are passed down the transport chain?

A

Release energy

Energy is used to actively transport H+ ions into inter membrane space across inner mitochondrial membrane

30
Q

Energy is released in stages in the electron transport chain. What is the advantage of this?

A

More efficient. Less energy is lost as heat

31
Q

How is ATP synthesised in oxidative phosphorylation?

A

Protons accumulate in the inner membrane space creating a high concentration of protons
Protons diffuse back via ATP synthase channels
ATP is synthesised via chemiosmosis

32
Q

Explain the process that occurs at the end of the electron transport chain

A

Oxygen acts as a terminal acceptor

Electrons combine with hydrogen ions and oxygen to form water

33
Q

What is oxidative phosphorylation?

A

Phosphorylation of ADP to form ATP using energy released by electrons in the electron transport chain

34
Q

Define the term ‘obligate anaerobes’

A

Organisms that cannot survive in the presence of oxygen

35
Q

Define the term ‘facultative anaerobes’

A

Synthesis of ATP by aerobic respiration if oxygen is present, but can switch to anaerobic respiration in the absence of oxygen

36
Q

Define the term ‘obligate anaerobes’

A

Can only synthesise oxygen in the presence of oxygen

37
Q

Define the term ‘fermentation’

A

The process by which complex organic compounds are broken down into simpler inorganic compounds without the use of oxygen or the involvement of the electron transport chain

38
Q

How is ATP produced in anaerobic respiration?

A

Substrate level phosphorylation

39
Q

What are the two types of anaerobic respiration?

A

Alcoholic fermentation

Lactate fermentation

40
Q

Where does alcoholic fermentation take place?

A

Yeast and some plant root cells

41
Q

Where does lactate fermentation occur?

A

Animal cells

42
Q

Explain the effects of a lack of oxygen on the process of respiration

A

No oxygen = no terminal electron acceptor in oxidative phosphorylation
Flow of electrons stop
Synthesis of ATP by chemiosmosis stops
NADH and FADH2 have nowhere for electrons to go
Oxidation of pyruvate and Krebs cycle stop

43
Q

Explain the process of lactate fermentation

A

Pyruvate acts as a hydrogen acceptor for hydrogen from NADH
Catalysed by lactate dehydrogenase
Pyruvate converted into lactate
NAD is regenerated

44
Q

How does glycolysis not stop despite lack of oxygen?

A

Fermentation regenerates NAD which is input into glycolysis

45
Q

How is lactic acid stored in the body?

A

Converted to glucose in the liver

Oxygen needed for this process creating an oxygen debt

46
Q

What are the two main reasons lactic acid cannot occur indefinitely?

A

Reduced quantity of ATP produced would not be enough to sustain vital processes for a long period of time
Accumulation of lactic acid causes a fall in pH leading to proteins denaturing. Respiratory enzymes and muscle filaments cease to function at low pH

47
Q

Is lactate fermentation reversible?

A

Yes

48
Q

Is alcoholic fermentation reversible?

A

No

49
Q

Explain the process of alcoholic fermentation

A

Pyruvate converted to ethanal, catalysed by pyruvate decarboxylase
Ethanal accepts a hydrogen atom from reduced NAD forming ethanol
NAD acts as a coenzyme and glycolysis continues

50
Q

How long can alcoholic fermentation last for?

A

Continue indefinitely

Ethanol is a toxic waste product to yeast cells and they are unable to survive if ethanol accumulates above 15%

51
Q

Define respiratory substrate

A

Any biological molecule that can be broken down in respiration to release energy

52
Q

Why does the energy each respiratory substrate release differ?

A

Depends on the different amounts of hydrogen in the molecules. The more hydrogen the more enzymes can be reduced to be used in the ETC

53
Q

What is the name of the process of removing an amine group?

A

Deamination

54
Q

How do proteins form respiratory substrates?

A

Proteins are hydrolysed to amino acids
Amino acids are deaminated in the liver
Enter respiratory pathway normally via pyruvate

55
Q

How do fatty acids form respiratory substrates?

A

Triglycerides are hydrolysed into fatty acids and glycerol
Fatty acids form Acetyl CoA
Glycerol converted into pyruvate. Undergoes oxidative carboxylation forming acetyl. Picked up by co A to form acetyl CoA

56
Q

What is the respiratory quotient a measure of?

A

The amount of CO2 produced in respiration relative to the levels of oxygen used in respiration

57
Q

What is the purpose of the respiratory quotient?

A

Gives an indication of the type of respiratory substrate being produced

58
Q

How is the respiratory quotient measured?

A

Using a respirometer

59
Q

What is a normal respiratory quotient?

A

0.8-0.9

60
Q

What levels does the respiratory quotient reach during anaerobic respiration?

A

Above 1

Biology OCR A A level (17 decks)

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