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A2 Biology > 5.2.2 > Flashcards

5.2.2 Flashcards

1
Q

What is glycolysis?

A

The breakdown of 1 glucose molecule into 2 pyruvate molecules

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2
Q

Is glycolysis aerobic or anaerobic?

A

Glycolysis is anaerobic

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3
Q

Where does glycolysis take place?

A

The cytoplasm of the cell

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4
Q

What are the four main steps in glycolysis?

A

Phosphorylation
Lysis
Phosphorylation
Dehydrogenation and formation of ATP

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5
Q

Describe the first phosphorylation in glycosis

A

Two molecules of ATP release one phosphate group each, which bind to a glucose molecule, forming hexose bisphosphate

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6
Q

Describe lysis in glycolysis

A

The formation of hexose bisphosphate destabilises the molecule, causing it to split into two triose phosphate (TP) molecules

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7
Q

Describe lysis in glycolysis

A

The formation of hexose bisphosphate destabilises the molecule, causing it to split into two triose phosphate (TP) molecules

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8
Q

Describe the second phosphorylation in glycolysis

A

Another phosphate group is added to each triose phosphate, forming triose bisphosphate. The phosphate groups come from free inorganic phosphate ions in the cytoplasm

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9
Q

Describe dehydrogenation and formation of ATP in glycolysis

A

Two phosphate groups are removed from each triose bisphosphate molecule, forming 4 ATP molecules. The two triose bisphosphate molecules are oxidised by the removal of hydrogen atoms, forming two pyruvate molecules. NAD coenzymes accept the hydrogens, reducing them

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10
Q

What type of phosphorylation is seen in glycolysis?

A

Substrate level phosphorylation

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11
Q

What is substrate level phosphorylation?

A

The formation of ATP without the involvement of an electron transport chain

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12
Q

What are the net products of glycolysis?

A

2 ATPs, 2 NADHs, and 2 pyruvates

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13
Q

What is the first step of AEROBIC respiration?

A

The link reaction

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14
Q

Where does the link reaction take place?

A

The mitochondrial matrix

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15
Q

How does pyruvate enter the mitochondrial matrix?

A

Active transport

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16
Q

What happens during oxidative decarboxylation of pyruvate?

A

Carbon dioxide is removed, as well as hydrogen

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17
Q

What accepts the removed hydrogens?

A

NAD, forming reduced NAD

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18
Q

What is formed after CO2 and hydrogen are removed?

A

An acetyl group

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19
Q

What happens to the acetyl group next?

A

It binds to coenzyme A, forming acetyl CoA

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20
Q

What are the net products of the link reaction?

A

2 CO2s, 2 NADHs, 2 acetyl CoAs

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21
Q

Where does the Krebs cycle take place?

A

The mitochondrial matrix

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22
Q

What is the first step in the Krebs cycle?

A

Acetyl CoA delivers an acetyl group to the Krebs cycle. The acetyl group combines with oxaloacetate (OAA) to form citrate (6C)

23
Q

What is the second step in the Krebs cycle?

A

The citrate molecule undergoes decarboxylation and dehydrogenation producing one NADH and one CO2. A 5 carbon intermediate is formed

24
Q

What is the third step in the Krebs cycle?

A

The 5 carbon intermediate undergoes further decarboxylation and dehydrogenation reations, regenerating OAA, so the cycle continues. Two more NADHs and one FADH2 is formed.

25
Q

How many times does the Krebs cycle take place per glucose molecule?

A

2 times

26
Q

What are the net products of the Krebs cycle?

A

2 ATPs, 4 CO2s, 6 NADHs, and 2 FADHs

27
Q

How many ATPs does NADH cause the synthesis of?

A

3 ATPs

28
Q

How many ATPs does FADH2 cause the synthesis of?

A

2 ATPs

29
Q

What is the final stage of aerobic respiration?

A

Oxidative phosphorylation

30
Q

What happens at the start of oxidative phosphorylation?

A

The hydrogen atoms that have been collected by NAD and FAD are delivered to electron transport chains in the membranes of the cristae of the mitochondria. The hydrogen atoms dissociate into hydrogen ions and electrons.

31
Q

What do the electrons do in oxidative phosphorylation?

A

The electrons reduce and oxidise the electron carriers as they flow down the electron transport chain. This causes energy to be released. This energy is used to create a proton gradient leading to diffusion of protons through channel proteins lined with ATP synthase, resulting in the synthesis of ATP

32
Q

What happens at the end of the electron transport chain?

A

The electrons combine with hydrogen ions and oxygen, which is the final electron acceptor, to form water. The electron transport chain cannot operate unless oxygen is present, so respiration that results in the complete breakdown of glucose is an aerobic process

33
Q

Why is it called oxidative phosphorylation?

A

The phosphorylation of ADP to form ATP is dependent on electrons moving along electron transport chains. The electron transport chains require the presence of oxygen

34
Q

How many ATP molecules are produced from aerobic respiration?

A

38 ATPs

35
Q

What are obligate anaerobes?

A

Organisms that cannot survive in the presence of oxygen. Most obligate anaerobes are prokaryotes

36
Q

What are facultative anaerobes?

A

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

37
Q

What are obligate aerobes?

A

Organisms that can only synthesise ATP in the presence of oxygen

38
Q

What is fermentation?

A

Fermentation is a form of anaerobic respiration in which complex organic compounds are broken down into simpler inorganic compounds without the use of oxygen or the involvement of an electron transport chain

39
Q

What is fermentation?

A

Fermentation is a form of anaerobic respiration in which complex organic compounds are broken down into simpler inorganic compounds without the use of oxygen or the involvement of an electron transport chain

40
Q

What is the net ATP produced in fermentation?

A

2 ATPs

41
Q

What is the net ATP produced in fermentation?

A

2 ATPs

42
Q

What are the two main types of fermentation?

A

Alcoholic fermentation and lactate fermentation

43
Q

Describe lactate fermentation in mammals

A

Pyruvate can act as a hydrogen acceptor, taking the hydrogen from reduced NAD, catalysed by lactate dehydrogenase. The pyruvate is converted into lactate and NAD is regenerated. This can be used to keep glycolysis going so a small amount of ATP is still synthesised.

44
Q

What is the reason for oxygen debt?

A

Lactic acid is converted back to glucose in the liver, but oxygen is required for this

45
Q

Why can’t lactate fermentation occur indefinitely?

A

The reduced quantity of ATP produced is not enough to maintain vital processes for long periods, and the accumulation of lactic acid causes a fall in pH leading to proteins denaturing.

46
Q

Describe alcoholic fermentation in yeast

A

Alcoholic fermentation is irreversible, unlike lactate fermentation. Pyruvate is first converted into ethanal, catalysed by pyruvate decarboxylase. Ethanal then accepts a hydrogen atom from NADH, forming ethanol. The regenerated NAD can continue to act as a coenzyme and glycolysis can continue

47
Q

What is a respiratory quotient?

A

A quality of a substrate to show the ratio between CO2 produced and O2 consumed

48
Q

How is respiratory quotient calculated?

A

RQ = CO2 produced/ O2 consumed

49
Q

What is the RQ of carbohydrates?

A

1.0

50
Q

What is the RQ of proteins?

A

0.9

51
Q

What is the RQ of lipids?

A

0.7

52
Q

What does it mean if the RQ value is greater than 1?

A

Anaerobic respiration is taking place

53
Q

What is used to measure RQ?

A

A respirometer

A2 Biology (14 decks)

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