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Biology - Module 5 > Respiration > Flashcards

Respiration Flashcards

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1
Q

What is the first stage of respiration?

A

Glycolysis

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2
Q

How many carbons does glucose have?

A

6

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3
Q

What happens to glucose in glycolysis?

A

It is broken down to 2 pyruvate molecules.

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4
Q

How many carbons does pyruvate have?

A

3

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5
Q

What can happen to pyruvate after glycolysis?

A

It can either proceed in aerobic respiration and go through the link reaction or go through fermentation.

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6
Q

What happens to ADP in glycolysis?

A

It is oxidised to form 2 molecules of ATP.

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7
Q

What happens to NAD+ in glycolysis?

A

It is reduced to form 2 molecules of NADH.

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8
Q

What are the 3 products of glycolysis?

A

2 pyruvate, 2 NADH and 2 ATP

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9
Q

What is the second stage of respiration called?

A

The link reaction

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10
Q

Where does glycolysis occur?

A

The cell cytoplasm

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11
Q

Where does the link reaction occur?

A

The mitochondrial matrix

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12
Q

What happens to pyruvate in the link reaction?

A

It loses its carboxyl group and coenzyme A bonds to the remaining acetyl group forming acetyl coA.

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13
Q

What is decarboxylation and where does this occur in respiration?

A

It is the removal of a carboxyl group producing carbon dioxide. It occurs during the link reaction in the mitochondrial matrix, where pyruvate loses its carboxyl group.

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14
Q

How many carbon dioxide molecules are formed in the link reaction?

A

2

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15
Q

What is the pyruvate referred to as after losing its carboxyl group?

A

An acetyl group

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16
Q

Which coenzyme binds to the acetyl group?

A

Coenzyme A

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17
Q

How many carbons does acetyl coA have?

A

2

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18
Q

How many acetyl coA do we get at the end of the link reaction?

A

2 for each glucose molecule

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19
Q

What happens to NAD+ during the link reaction?

A

It is reduced to 2 molecules of NADH.

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20
Q

What catalyses the link reaction?

A

Pyruvate dehydrogenase

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21
Q

What is the third stage of respiration?

A

The Krebs cycle

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22
Q

Where does the Krebs cycle occur?

A

In the mitochondrial matrix.

23
Q

In the first stage of the Krebs cycle, what is transferred by acetyl coA?

A

Acetyl coA transfers its acetyl group to oxaloacetic acid, forming citric acid.

24
Q

How many carbons does oxaloacetic acid have?

A

4

25
Q

How many carbons does citric acid have?

A

6

26
Q

What are the products of the Krebs cycle?

A

6NADH, 4CO2, 2ATP and 2FADH2

27
Q

What is the final stage of respiration?

A

Oxidative phosphorylation

28
Q

Where does oxidative phosphorylation take place?

A

The inner mitochondrial membrane

29
Q

What happens to NADH in oxidative phosphorylation?

A

NADH donates protons and electrons and these electrons are received by electron acceptors in the membrane along the electron transport chain. As a result, 10 NAD+ are formed having been oxidised.

30
Q

What happens as the electrons in the electron transport chain go from a high energy state to low energy state?

A

Energy is released which is used to pump protons (from the NADH) into the intermembrane space, which creates a proton gradient - electrochemical gradient.

31
Q

What is the electrochemical gradient between the intermembrane space and mitochondrial matrix?

A

It happens as a result of hydrogen ions being pumped into the intermembrane space causing a build up of both these ions and positive charge.

32
Q

How do the hydrogen ions leave the intermembrane space?

A

They leave via ATP synthase along with ADP and phosphate molecules which causes around 38 ATP to be synthesised.

33
Q

What does oxygen do in respiration?

A

At the end of oxidative phosphorylation it acts as the final electron acceptor, forming 6 water molecules.

34
Q

What are the products of oxidative phosphorylation?

A

10 NAD+, 6H2O and 38 ATP

35
Q

Which coenzymes are used in respiration?

A

NAD in glycolysis, link reaction, the Krebs cycle and oxidative phosphorylation (NADH). FAD in the Krebs cycle. And coenzyme A in the link reaction.

36
Q

What is the role of mitochondrial cristae in respiration?

A

They increase the surface area of the inner mitochondrial membrane where oxidative phosphorylation takes place, allowing this to occur at a quicker rate.

37
Q

Why might anaerobic respiration happen instead of aerobic respiration?

A

When oxygen is not around to act as the final electron acceptor at the end of the electron transport chain.

38
Q

What is anaerobic respiration also called in some cases?

A

Fermentation

39
Q

How is anaerobic cellular respiration similar to aerobic cellular respiration?

A

Electrons extracted from a fuel molecule are passed through an electron transport chain, driving ATP synthesis.

40
Q

How is anaerobic cellular respiration different from aerobic cellular respiration?

A

Instead of oxygen, organisms use other molecules such as sulfate or nitrate as the final electron acceptor at the end of the transport chain.

41
Q

What kinds of organisms use anaerobic cellular respiration?

A

Some prokaryotes—bacteria and archaea—that live in low-oxygen environments rely on anaerobic respiration to break down fuels e.g. methanogens.

42
Q

What are the stages of fermentation?

A

Glycolysis plus one or two extra reactions tacked on at the end.

43
Q

What is the purpose of the extra reactions after glycolysis in fermentation?

A

To regenerate the electron carrier NAD+ from the NADH produced in glycolysis. The extra reactions accomplish this by letting NADH drop its electrons off with an organic molecule (such as pyruvate, the end product of glycolysis). This drop-off allows glycolysis to keep running by ensuring a steady supply of NAD+.

44
Q

What happens to pyruvate in lactic acid fermentation?

A

2 NADH transfer its electrons directly to pyruvate, generating 2NAD+ and 2 lactate as a byproduct.

45
Q

How is lactic fermentation important for food?

A

The bacteria that make yogurt carry out lactic acid fermentation.

46
Q

Where in the body does lactic acid fermentation take place?

A
  1. Red blood cells (do not have mitochondria to carry out cellular respiration).
  2. Muscle cells do this but only when there is too little oxygen for aerobic respiration to continue. Lactic acid produced in muscle cells is transported through the bloodstream to the liver, where it’s converted back to pyruvate and processed normally in the remaining reactions of cellular respiration.
47
Q

What did people used to think lactate did to the body after exercising too hard?

A

It was once thought that the accumulation of lactate in muscles was responsible for soreness caused by exercise, but recent research suggests this is probably not the case.

48
Q

In what organism does alcohol fermentation take place?

A

Yeast

48
Q

What happens in alcohol fermentation?

A

In the first step, a carboxyl group is removed from the 2 pyruvate and released in as 2 carbon dioxide, producing 2 acetaldehyde (2 carbon molecule). In the second step, 2NAD+ passes its electrons to acetaldehyde, regenerating 2NADH and forming 2 ethanol.

49
Q

What is the difference in relative energy values of
carbohydrates, lipids and proteins as respiratory
substrates?

A

Lipids = 0.7
Proteins = 0.9
Carbohydrates = 1.0

50
Q

How do you calculate the respiratory quotient (RQ)?

A

RQ = CO2 produced / O2 consumed

51
Q

What would an RQ of 1 suggest?

A

A dependence on carbohydrate.

52
Q
A

Biology - Module 5 (2 decks)

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