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A LEVEL BIOLOGY > 3 - Respiration (C1) > Flashcards

3 - Respiration (C1) Flashcards

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1
Q

Where does glycolysis occur?

A

In the cytoplasm of cells

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2
Q

What are the products of glycolysis?

A
  • 4 ATP (2 used, 4 produced = 2 ATP profit)
  • 2 pyruvate
  • 2 NADH
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3
Q

What is the process of glycolysis?

A
  • 2 ATPs attach 2 phosphates to glucose, forming hexose biphosphate and 2 ADPs
  • Hexose biphosphate splits into 2 triose phosphates
  • Each triose phosphate is oxidised as NAD is reduced to NADH +H+
  • 2 ADPs are phosphorylated, forming pyruvate
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4
Q

Where does the link reaction occur?

A

Matrix of mitochondria

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5
Q

What is the process of the link reaction?

A
  • Each pyruvate molecule is oxidised (dehydrogenated) as NAD is reduced to NADH +H+
  • CoA is added
  • CO2 is removed (decarboxylation)
  • Acetyl CoA is formed
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6
Q

What are the products of the link reaction?

A

Total of both pyruvate molecules:

  • 2 acetyl coA
  • 2 CO2
  • 2 NADH
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7
Q

What happens in the Krebs cycle?

A
  • Coenzyme A is removed from acetyl coenzyme A
  • Acetate (2C) is picked up by oxaloacetate (C4) forming citrate (C6)
  • Citrate has 2 CO2s removed, 1 ADP+pi is phosphorylated to ATP, 3 NADs are reduced to NADHs, 1 FAD is reduced to FADH
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8
Q

What happens to the energy released from C-H bonds in the Krebs cycle?

A

It’s transferred to the high energy electron carriers NAD and FAD

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9
Q

How do fatty acids enter the Krebs cycle?

A
  • Via Beta oxidation
  • Long chain fatty acid molecules are split into 2C acetate fragments and are fed into the Krebs cycle as acetyl co-enzyme A
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10
Q

How does glycerol enter the Krebs cycle?

A

It’s converted to triose phosphate

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11
Q

How do proteins enter the Krebs cycle?

A
  • Protein is hydrolysed to amino acids which are deaminated in the liver
  • The amino groups combine with CO2 making urea, which requires 2 ATPs
  • The remains are converted to acetyl CoA, pyruvate or another Krebs cycle intermediate
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12
Q

What is the primary, secondary and final energy source?

A

1 - Carbohydrates
2 - Fat
Last resort - Body proteins

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13
Q

Why is it difficult to transfer fat in the blood?

A

As they’re non-polar

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14
Q

Why is it easy to transfer carbohydrates in the blood?

A

As they’re polar and soluble

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15
Q

Can fats be respired anaerobically?

A

No

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16
Q

Can carbohydrates be respired anaerobically?

A

Yes

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17
Q

Why do lipids yield twice the ATP of carbohydrates?

A
  • The energy used to drive oxidative phosphorylation is in the electrons attached to the hydrogen atoms released by dehydrogenase enzymes
  • Lipids have twice as many hydrogens as carbohydrates, so:
  • 2x the hydrogens are released during respiration
  • 2x the reduced NAD/FAD take hydrogen to the ETC
  • 2x high energy electrons are passed down the carrier chain providing energy for proton pumps
  • 2x protons are pumped into the intermembrane space
  • 2x protons pass through ATP synthase to build ATP from ADP + Pi
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18
Q

What happens at the electron transport chain?

A
  • NAD and FAD transport H+ to the ETC where it divides into high energy electrons and protons
  • Electrons are passed backwards and forwards across the inner mitochondrial space by electron carriers
  • Energy in electrons is used by H+/proton pumps which pump H+ into the inter-membrane space
  • This builds an electrochemical gradient allowing ATP synthesis to occur by chemiosmosis as protons diffuse through ATPase
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19
Q

Why is oxygen the final electron and proton acceptor and what’s its role?

A
  • As it combines with electrons and hydrogens forming H2O (oxidative phosphorylation / photophosphorylation)
  • Maintains gradients as it removes e- and H+
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20
Q

What does reduction mean?

A

Gaining an electron

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21
Q

What does oxidation mean?

A

Losing an electron

22
Q

What is the definition of respiration?

A

The breakdown of complex food molecules to release ATP

23
Q

What are the 3 major types of respiration?

A
  • Aerobic respiration of fat (at rest)
  • Aerobic respiration of glucose (moderate exercise)
  • Anaerobic respiration of glucose (violent exercise)
24
Q

Where does the electron transport chain occur?

A

In the inner membrane of mitochondria

25
Q

How many reduced NAD and FAD are produced from the complete oxidation of 1 glucose molecule?

A
  • 10 reduced NAD

- 2 reduced FAD

26
Q

How many ATPs are produced from the ETC from the oxidation of each reduced NAD and FAD?

A
  • Each NAD - 3 ATPs, using 3 proton pumps

- Each FAD - 2 ATPs, using 2 proton pumps

27
Q

What does pyruvate from glycolysis form in anaerobic respiration?

A

The reduced NAD formed in glycolysis transfers the hydrogen to pyruvate, to form lactic acid in animals, and ethanol and CO2 in plants

28
Q

What is the yield of ATP in anaerobic respiration?

A
  • 2 ATPs in glycolysis (substrate-level phosphorylation)

- The 2 reduced NAD formed in glycolysis are oxidised when 2 pyruvates are reduced to a lactate

29
Q

How many ATP molecules are formed per glucose molecule?

A
  • 2 ATPs in glycolsis (substrate-level phosphorylation)
  • 2 ATPs in Krebs cycle (substrate-level phosphorylation)
  • 34 ATPs from oxidative phosphorylation (using chemiosmosis)
30
Q

Why is the maximum yield of ATP molecules per glucose often not obtained?

A
  • Due to leaky membranes

- ATP is used to move pyruvate, ADP, and reduced NAD and FAD across mitochondrial membrane

31
Q

What is the definition of aerobic respiration?

A

The release of large amounts of energy as ATP from the breakdown of molecules, with O2 as the final electron acceptor

32
Q

What is the definition of anaerobic respiration?

A

The breakdown of molecules in the absense of O2, releasing little energy and making a small amount of ATP by substrate-level phosphorylation

33
Q

Why can’t glycolysis constantly continue during anaerobic respiration?

A

As NAD will run out if it is not being oxidised again (either by the ETC or fermentation)

34
Q

Why is a build up of lactic acid in muscles bad?

A

As it causes muscle fatigue

35
Q

What is lactic acid fermentation?

A

A series of anaerobic reactions in animal cells where pyruvate uses reduced NAD to form lactic acid (lactate) and NAD. This NAD can be reduced again in glycolysis.

36
Q

What are the 2 different types of fermentation?

A
  • Lactic acid fermentation

- Alcoholic fermentation

37
Q

What is alcoholic fermentation?

A
  • Anaerobic process in which cells convert pyruvate into CO2 and ethanol
  • Pyruvate is broken down to ethabal by releasing a CO2 molecule
  • The ethanal accepts the H+ from reduced NAD to form ethanol
  • NAD can then be reduced again in glycolysis
  • Happens in yeast and some plant cells
38
Q

What is a disadvantage of alcoholic fermentation?

A

It’s irreversible and ethanol can build to toxic levels

39
Q

Why is ATP needed for glycolysis?

A

To phosphorylate glucose, which lowers the activation energy needed and stops it diffusing out the cell

40
Q

How does a camels hump produce metabolic water?

A
  • Long, fatty acid tails are converted into many acetate, which are dehydrogenated and decarboxylated, producing lots of CO2 and reduced NAD
  • Reduced NAD and FAD carry the hydrogen to the inner mitochondrial membrane where O2 is the final electron acceptor, forming H2O used by camel
41
Q

Why does having a large number of proton pores in the inner mitochondrial membrane result in a person being less likely to gain weight?

A
  • Larger number of proton pores means protons leak back into matrix
  • This reduces yield of ATP from chemiosmotic gradients and so less ATP is made from oxidative phosphorylation
  • This means food isn’t converted to ATP as efficiently and fats aren’t stored as well, so these people don’t gain as much weight
42
Q

What is a metabolic pathway?

A

A sequence of reactions controlled by enzymes

43
Q

Where does oxidative phosphorylation occur?

A

On the inner membranes of mitochondria in aerobic respiration

44
Q

Where does photophosphorylation occur?

A

On the thylakoid membranes of the chloroplasts in the light-dependent stage of photosynthesis

45
Q

Where does substrate-level phosphorylation occur?

A

When phosphate groups are transferred from donor molecules e.g. G3P to ADP to make ATP in glycolysis, or when enough energy is released for a reaction to bind ADP to inorganic phosphate

46
Q

What are obligate aerobes?

A

Organisms that use aerobic respiration only, so can’t respire in the absense of O2

47
Q

What are facultative anaerobes?

A

Microorganisms that respire aerobically, but can also respire anaerobically in the absense of O2

48
Q

What are obligate anaerobes?

A

Some bacteria which use anaerobic respiration, and can’t respire in the presence of O2

49
Q

What is a coenzyme?

A

A molecule required by an enzyme in order to function

50
Q

What does cyanide, a non-competitive inhibitor, do in the ETC?

A
  • It stops electrons and protons being transferred to water, so they accumulate and destroy the proton gradient
  • ATP synthetase can’t operate and the cell dies quickly
51
Q

What do longer fatty acid chains that enter the Krebs cycle have?

A
  • More carbon atoms - so more CO2 is produced

- More hydrogen atoms - so more NAD is reduced, so more ATP is produced, also more H2O is produced

A LEVEL BIOLOGY (13 decks)

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