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2B > Respiration > Flashcards

Respiration Flashcards

1
Q

Outline aerobic respiration.

A

Requires oxygen and produces CO2, water and lots of ATP.

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2
Q

Outline anaerobic respiration.

A

Doesn’t need oxygen. Produces lactate (animals) or ethanol and carbon dioxide (plants and fungi). Produces only a little ATP.

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3
Q

What does anaerobic respiration produce in animals?

A

Lactate

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4
Q

What does anaerobic respiration produce in plants?

A

Ethanol and CO2.

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5
Q

What does anaerobic respiration produce in fungi?

A

Ethanol and CO2.

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6
Q

What are the four stages that aerobic respiration are split into?

A
  1. Glycolysis
  2. Link reaction
  3. Krebs cycle
  4. Oxidative phosphorylation
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7
Q

In one sentence, summarise what glycolysis is.

A

Am anaerobic process involving the splitting of glucose (6C) into two pyruvate (3C).

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8
Q

Where does glycolysis occur?

A

The cytoplasm

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9
Q

Outline glycolysis.

A
  1. Phosphorylation occurs. This is because 2 ATP are hydrolysed into 2 ADP+Pi (2 glucose phosphate).
  2. Each molecule of phosphorylated glucose is split into 2x triose phosphate (3C).
  3. This triose phosphate is oxidised, forming 2x pyruvate.
    Then, the hydrogen (lost from oxidation) is transferred to NAD to form NADH.
  4. 4 ATP produced (so net gain of 2).
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10
Q

What are the products of glycolysis?

A

2x ATP molecules, 2x pyruvate, and 2x NADH.

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11
Q

Where does a H+ come from in glycolysis to produce NADH?

A

The H+ is lost from the oxidation (of triose phosphate (which produces 2x pyruvate)).

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12
Q

In glycolysis, how many ATP molecules are produced?

A

4 (but net gain of 2).

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13
Q

What does glycolysis provide evidence for?

A

Evolution. As it’s a universal feature of every living organism.

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14
Q

Why doesn’t glycolysis need organelles for the process to occur?

A

Because the enzymes for the glycolytic pathway are already found in the cytoplasm of cells.

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15
Q

How many carbons does triose phosphate have in glycolysis?

A

3C

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16
Q

How many carbons does pyruvate have?

A

3C

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17
Q

What is pyruvate?

A

An acid with 3C

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18
Q

In one sentence, summarise the link reaction.

A

The 3C pyruvate molecules enter a series of reactions which lead to the formation of acetyl COA (2C).

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19
Q

Outline the link reaction.

A
  1. The two pyruvate molecules are actively transported into the matrix of mitochondria.
  2. The pyruvate is oxidised to acetate. (In this, the 3C pyruvate loses a CO2 molecule and 2 hydrogens (which are then used to form NADH)).
  3. The 2C acetate combines with COA to produce acetyl COA.
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20
Q

What is the overall equation of the link reaction?

A

Pyruvate + NAD + CoA —> acetyl CoA + NADH + CO2.

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21
Q

How many times do the LR and KC occur for every glucose molecule?

A

Twice

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22
Q

Why does the LR and KC occur twice for every glucose molecule?

A

Because two pyruvate molecules are made for every glucose entering glycolysis

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23
Q

How much ATP is produced in the link reaction?

A

None

24
Q

In one sentence, summarise what the Krebs Cycle is.

A

The introduction of acetyl CoA into a cycle of oxidisation-reduction reactions that yield some ATP and a large quantity of NADH and FADH.

25
Q

How do the pyruvate molecules get from glycolysis to the link reaction?

A

The two pyruvate molecules are actively transported into the matrix of the mitochondria for the LR.

26
Q

Outline the process of the Krebs Cycle.

A
  1. Acetyl CoA (from LR) combines with a 4C to produce a 6C molecule.
  2. In a series of oxidisation-reduction reactions, the 6C then loses 2x CO2 and hydrogen to give a 4C molecule, and 1x ATP due to substrate-level phosphorylation.
  3. The 4C molecule can now combined with a new molecule of acetyl CoA to being the cycle again.
27
Q

Why is the Krebs Cycle process known as a cycle?

A

Because acetyl CoA combines with a 4C molecule (to produce a 6C).
But in oxidisation-reduction reactions, the 6C loses 2x CO2 to give a 4C molecule again.
This 4C can then combine with a new molecule of acetyl CoA to begin the cycle again.

28
Q

How many molecules of ATP does the Krebs Cycle produce?

A

1

29
Q

How many molecules of CO2 does the Krebs Cycle release?

A

2

30
Q

How many molecules of CO2 does the LR and KC produce?

A

3

31
Q

What are coenzymes?

A

Molecules that some enzymes require in order to function. They are important in respiration and photosynthesis.

32
Q

Why is NAD the most important carrier in respiration?

A

Because it works with dehydrogenase enzymes (that catalyse the removal of hydrogen atoms from substrates, and transfer them to other molecules involved in oxidative phosphorylation).

33
Q

Why is the Krebs Cycle so important? (4)

A
  • it breaks down macromolecules into smaller ones (eg pyruvate is broken down into CO2).
  • it regenerates the 4C molecule that combines with acetyl CoA, which would otherwise accumulate.
  • it produces H+ aroma that are carried by NAD to the electron transfer chain and provide energy for oxidative phosphorylation. This leads to the production of ATP that provides metabolic energy for the cell.
  • it’s a source of intermediate compounds used by cells in the manufacture of other important substances eg chlorophyll.
34
Q

Name the 2C molecule that pyruvate is converted to during the LR.

A

Acetate

35
Q

State in which part of the cell the KC takes place.

A

In the matrix of mitochondria

36
Q

In one sentence, summarise oxidative phosphorylation.

A

Energy carried by electrons from received coenzymes (NADH and FADH) is used to make ATP.

37
Q

Outline the process of oxidative phosphorylation

A
  1. NADH and FADH donate the electrons of their hydrogen atoms to the first molecule in the electron transfer chain.
  2. The electrons pass along a chain of electron transfer carrier molecules in a series of oxidation-reduction reactions.
    As the electrons flow along the chain, the energy they release causes the active transport of protons across the inner mitochondrial membrane into the inter-membrane space.
  3. Protons accumulate in the inner membrane space. Then, they diffuse back into the matrix through ATP synthase channels embedded in the inner mitochondrial membrane.
  4. At the end of the chain, electrons and protons combine with oxygen to form water. (Oxygen is the terminal acceptor of electrons).
38
Q

In oxidative phosphorylation, what do NADH and FADH donate their hydrogen atoms to?

A

The first molecule in the electron transfer chain.

39
Q

In oxidative phosphorylation, how do electrons pass along the chain of electron transfer carrier molecules?

A

In a series of oxidation-reduction reactions.

40
Q

In oxidative phosphorylation, happens when electrons flow along the chain of electron transfer carrier molecules?

A

As electrons flow along the chain, the energy they release causes the active transport of protons across the inner mitochondrial membrane -> the inter-membrane space.

41
Q

In oxidative phosphorylation, how do protons diffuse back into the matrix?

A

Protons have accumulated in the inner-membranal space creating a higher conc.

Then, they can diffuse through ATP synthase channels embedded in the inner mitochondrial membrane.

42
Q

How is water formed in oxidative phosphorylation?

A

At the end of the chain, electrons and protons combine with oxygen to form water.

43
Q

What is the terminal acceptor of electrons in oxidative phosphorylation?

A

Oxygen.

44
Q

Where does oxidative phosphorylation occur?

A

In the cristae in mitochondria.

45
Q

Why is oxygen important as the final acceptor of hydrogen atoms?

A

Because without its told in removing hydrogen atoms at the end of the chain, the hydrogen ions (protons) and electrons would ‘back up’ along the chain and the process of respiration would come to a halt.

46
Q

Why are electrons carried by NAD and FAD passed along a series of electron transfer carrier molecules?

A

Because the electrons therefore move down an energy gradient, which allows their energy to be released gradually and therefore more usefully (as less is lost as heat).

47
Q

What 3 substances can be oxidised by cells to release energy?

A

Sugars (glucose, standard)
Lipids
Proteins

48
Q

Outline how lipids can be used as a respiratory substrate.

A
  1. Lipids are hydrolysed to glycerol + fatty acids.
  2. The glycerol is then phosphorylated and converted -> triose phosphate which enters the glycolysis pathways and subsequently KC.
  3. The fatty acid is broken down into 2C which are converted to acetyl CoA which then enters the KC.
  4. This oxidation of lipids produces 2C fragments of carbohydrate and many hydrogen atoms. Said hydrogen atoms are then used to produce ATP during OP.
49
Q

Outline how proteins can be used as a respiratory substrate.

A
  1. It is hydrolysed into its constituent AA.
  2. These have their amino group removed (deamination) before entering the respiratory pathway at diff points depending on the number of carbon atoms they contain.

(3C -> pyruvate).
(4C and 5C -> intermediates in the KC).

50
Q

The surface of the inner mitochondrial membrane is highly folded to form christae. What’s the advantage of this?

A

Provides a greater SA of membrane incorporating enzymes and other proteins involved in OP.

51
Q

Why can the KC or electron transfer chain not work in the absence of oxygen?

A

Because soon all of the NAD and FAD will be reduced, so will not be available to take up the H+ produced during the KC and so the enzymes stop working.

52
Q

Anaerobic respiration participates in glycolysis. Why is this not that great?

A

It’s quick, but not as efficient as aerobic, because there is an incomplete breakdown of glucose.

53
Q

In anaerobic respiration, why is ethanol / lactate produced?

A

Ethanol / lactate regenerates oxidised NAD, meaning glycolysis can continue despite a lack of oxygen - meaning a small amount of ATP can still be produced.

54
Q

Why is lactate bad?

A

Because a build up can cause cramp and muscle fatigue (if it accumulates in muscle tissue). Also, as it’s an acid, it also causes pH change which affects enzymes.

55
Q

How is lactate removed?

A

Lactate is removed by the blood and taken to the liver to be converted into glycogen.

2B (26 decks)

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