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Respiration Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

Explain why all life needs to perform respiration.

A

Cells need energy for three main types of activity -
transport, synthesis and movement.

transport of veisicles, DNA replication, protein synthesis and muscle contraction.

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2
Q

Explain why ATP is a better, immediate source of energy for metabolic reactions than glucose.

A
  • The interconversion of ATP and ADP is happening constantly in cells, meaning cells do not need a large source of ATP. ATP is therefore a good immediate energy source.
  • Contains bonds between phosphates with intermediate energy: large enough to be useful for cellular reactions but no so large that energy is waster as heat, potentially causing enzymes to denature.
  • Energy released in small bursts
  • Easily regenerated.
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3
Q

Describe 4 metabolic activities that require ATP.

A
  • Active transport
  • Synthesis of biomolecules
  • transport
  • movement
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4
Q

Draw, label and annotate a diagram of a mitochondrion.

A
  • Outer mitochondrial membrane: separates the contents of the mitochondrian from the rest of the cell. Creates cellular compartment with ideal conditions for aerobic respiration.
  • inner mitochondrial membrane: contains electron transport chain and ATP synthase.
  • Cristae: projections of the inner membrane which increase the SA available for oxidative phosphorylation.
  • Matrix: contains enzymes for the krebs cycle and the link reaction, also contains mitochondrial DNA.
  • intermembranal space: proteins are pumped into this space by the electron transport chain. The space is so small the concentration buids up quickly.
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5
Q

State the site of glycolysis within cells.

A

Cytoplasm of the cell.

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6
Q

Draw a diagram to show the process of glycolysis.

A

1) Phosphorylation - the first step of glycolysis requires two molecules of ATP. Two phosphates released from two molecules of ATP, are attached to a glucose molecule forming hexose bisphosphate.
2) Lysis - this destablises the molecule causing it to split into two triose phosphate molecules.
3) Phosphorylation - another phosphate group is added to each triose phosphate forming two triose biphosphate molecules. These photophate groups come from free inorganic phosphate ions present in the cytoplasm.

4) Dehydrogenation and formation of ATP - the two triose biphosphate molecules are then oxidised by the removal of hydrogen atoms (dehydrogenation) to form two pyruvate molecules. NAD coenzymes accept the removed hydrogens - they are reduced, forming two reduced NAD molecules.
5) 4 ATPS molecules are also produced using phosphates from triose biphosphate. (substrate level phosphorylation)

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7
Q

State the molecules required for glycolysis, the products from glycolysis, and the fate of the products from glycolysis.

A 
Requirements:
- 2 ATPs
- Glucose
- Phosphate ions 
- Coenzyme NAD 
Products:
- 4 ATPS
- 2 reduced NADs
- 2 molecules of pyruvate
Fate of products:
- ATP is used for energy 
- red NAD is used at a later stage to synthesis more ATP
- Pyruvate used in link reaction.
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8
Q

Give an example of substrate level phosphorylation.

A

The formation of ATP without involvement of an electron transport chain. ATP is formed by the transfer of a phosphate group from a phosphorylated intermediate (in this case triose biphosphate) to ADP.

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9
Q

Define the term “substrate level phosphorylation”

A

Synthesis of ATP by transfer of phosphate molecule from another molecule.

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10
Q

Define “dehydrogenation”.

A

The removal of a hydrogen atom.

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11
Q

State the site of the link reaction within cells.

A

in the matrix of the mitochondria.

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12
Q

Draw a diagram to show the process of the link reaction.

A

1) Pyruvate enters matrix by active transport.
2) Pyruvate undergoes oxidative decarboxylation - carbon dioxide is removed along with hydrogen.
3) The removed hydrogen atoms are accepted by NAD to form reduced NAD.
4) The resulting two-carbon acetyl group is bound by coenzyme A to form acetyl CoA.
5) Acetyl CoA delivers the acetyl group to the krebs cycle.
6) The reduced NAD is used in oxidative phosphorylation to produce ATP.
7) The CO2 produce will either diffuse away as metabolic waste or be used as a raw material for photosynthesis.

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13
Q

State the molecules required for the link reaction, the products of the link reaction, and the fate of the products from the link reaction.

A

Required:

  • Coenzyme A
  • pyruvate
  • NAD

Products

  • reduced NAD
  • acetyl CoA
  • CO2

Fate:

  • reduced NAD used in oxidative phosphorylation to produce ATP.
  • acetyl CoA passes on acetyl group to kreb cycle
  • CO2 produce will either diffuse away as metabolic waste or be used as a raw material for photosynthesis.
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14
Q

Define the term decarboxylation

A

Removal of a CO2

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15
Q

Define the term oxidative decarboxylation

A

Removal of carbon dioxide along with hydrogen.

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16
Q

State the site of the Kreb cycle within the cells

A

Mitochondrial matrix

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17
Q

Draw a diagram to show the process of the kreb cycle.

A

1) acetyl CoA delivers an acetyl group.
2) the 2 carbon acetyl group combines with the 4C oxaloacetate to make 6C citrate.
3) The 6C citrate molecules undergoes decarboxylation and dehydrogenation, producing 1 red NAD and 1 CO2. The loss of the carbon produces a 5C compound.
4) The 5C compound undergoes further decarboxylation and dehydrogenation reactions eventually regenerating the 4C oxaloacetate, and so the cycle continues.
5) While producing oxaloacetate, ATP is produced by substrate-level phosphorylation. This is the direct transfer of a phosphate group from an intermediate compound to ADP. In this phase, one more CO2, 1 red FAD and 2 red NAD are produced.

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18
Q

State the molecules required.

A
  • NAD
  • FAD
  • ADP
  • Acetyl CoA (the acetyl group)
  • Oxaloacetate (regenerated from the cycle)
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19
Q

State the products of the kreb cycle. (From two simultaneous cycles)

A
  • 6 red NAD (coenzyme that delivers electrons to electron transport chain)
  • 2 red FAD (coenzyme that delivers electrons to electron transport chain)
  • 2 ATP (for energy)
  • 4 C02 (by-product)
  • 2 Oxaloacetate (combines with acetyl in the kreb cycle)
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20
Q

Draw a table to summarise the products of glycolysis, link and kreb.

A

Look at notes.

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21
Q

Name three coenzymes involved in respiration and explain the function of each.

A

FAD and NAD: delivers electrons to electron transport chain.
Acetyl CoA: delivers acetyl group to kreb cycle.

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22
Q

Draw a table to show similarities and differences between NAD and FAD.

A

NAD - Takes part in all stages of cellular respiration. Accepts 1 hydrogen. Red NAD is oxidised at the start of the electron transport chain, releasing protons and electrons. Results in the synthesis of 3 ATP molecules.
FAD - only accepts hydrogen in the Kreb cycle. Accepts 2 hydrogens. Red FAD is reduced further along the chain. Results in synthesis of only 2 ATP molecules.

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23
Q

Define oxidative phosphorylation.

A

Oxidative phosphorylation is the process where energy carried by electrons, from coenzymes (NAD and FAD), is used to make ATP.

24
Q

Define the term electron carrier.

A

Proteins that accept and release electrons.

25
Q

Define electron transport chain.

A

An electron transport chain is made up of a series of electron carriers, each with progressively lower energy levels. As high energy electrons move from one carrier in the chain to another, energy is released.

26
Q

Define the term chemiosmosis.

A

The synthesis of ATP driven by the flow of protons across a membrane.

27
Q

State the site of oxidative phosphorlyation within the cells.

A

The inner folded membrane (the Cristae) of mitochondria.

28
Q

Describe the process of oxidative phosphorlyation.

A

1) Hydrogen atoms are released from coenzymes FAD and NAD and are delivered to the electron transport chain, present in the Cristae of the mitochondria.
2) The hydrogen atoms dissociate into H+ ions and electrons.
3) The high energy electrons are used in the synthesis of ATP by chemiosmosis.
4) Energy is released in redox reactions as the electrons reduce and oxidise electron carriers as they flow along the transport chain.
5) The energy is used to create a proton gradient, leading to the diffusion of protons through ATP synthase, resulting in the synthesis of ATP.
6) At the end of the chain, electrons combine with hydrogen ions and oxygen to form water. Oxygen is called the final electron acceptor and the electron chain cannot operate unless oxygen is present.

29
Q

Describe the role of the mitochondrial Cristae in oxidative phosphorlyation

A

The Cristae is the foldings in the inner mitochondrial membrane, which contains the electrons transport chain. The folding increases the SA available for respiration.

30
Q

State the molecules required for oxidative phosphoprlyation

A
  • FAD
  • NAD
  • Oxygen
31
Q

State the products of oxidative phosphorylation

A
  • Water (by product)

- ATP (used as energy)

32
Q

Define the terms “anaerobic respiration”.

A

Respiration in the absence of oxygen.

33
Q

Define the term “obligate anaerobe”.

A

Organisms that cannot live in environments containing oxygen.

34
Q

Define the term “facultative anaerobe”.

A

Organisms that can respire aerobically or anaerobically.

35
Q

Define the term “obligate aerobe”.

A

Organisms that can only respire aerobically.

36
Q

Define the term “fermentation”.

A

Anaerobic respiration without the involvement of an electron transport chain.

37
Q

Define the term “alcoholic fermentation”.

A

Fermentation that results in the production of ethanol.

38
Q

Name the types of cell that do alcoholic fermentation and the types of cell that do lactate fermentation.

A
  • Yeast and some plants root cells do alcoholic fermentation.
  • Animal cells do lactate fermentation.
39
Q

Define the term lactate fermentation.

A

Fermentation that results in the production of lactate.

40
Q

Describe the usefulness of anaerobic respiration.

A

It is a temporary emergency measure to keep vital processes running when oxygen cannot be supplied fast enough to respiring cells.

41
Q

Draw a diagram to show the process of alcoholic fermentation.

A

1) Pyruvate is converted to ethanal, catalysed by the enzyme pyruvate decarboxylase.
2) Ethanal can then accept a hydrogen atom from reduced NAD, becoming ethanol.
3) The regenerated NAD can then continue to act as a coenzyme and glycolysis can continue.
4) This can continue indefinitely in the absence of oxgen, but ethanol is toxic waste product to yeast. Yeast cells cannot survive in ethanol in a concentration.

42
Q

Draw a diagram to show the process of lactate fermentation.

A

1) In mammals, pyruvate can act as hydrogen acceptor taking the hydrogen from the reduced NAD. This is catalysed by the enzyme lactate dehydrogenase.
2) Pyruvate is converted to lactate (lactic acid) and NAD is regenerated.
3) This can be used to keep glycolysis going so a small quantity of ATP is synthesized.
4) In mammals, anaerobic respiration in the muscles is supported by ATP from aerobic respiration.
5) Lactic acid is converted back to glucose in the liver but oxygen is needed to complete this process. This is the reason for the oxygen debt (need to breathe heavily) after exercise.

43
Q

Give the two main reasons why lactate fermentation cannot occur indefinitely.

A
  • The reduced quantity of ATP produced would not be enough to maintain vital processes for a long period of time.
  • The accumulation of lactic acid causes a fall in ph leading to proteins denaturing. Respiratory enzymes are proteins and will cease to function at a low PH.
44
Q

Explain why the yield of ATP from anaerobic respiration is much lower than the yield from aerobic respiration.

A

1) Electron transport chain and kreb cycle come to a hault in the absence of oxygen.
2) When is there no oxygen to act as the final electron acceptor in oxidative phosphorylation, the flow of electrons stops. This means the synthesis of ATP by chemiosmosis stops.
3) As the flow of electrons along the electron transport chain stops, red NAD and red FAD can no longer be oxidised.
4) This means they cannot be regenerated so decarboxylation and oxidation of pyruvate and kreb cycle stop as there are no coenzymes available to accept the hydrogen atoms.
5) Glycolysis would also stop due to lack of NAD if it weren’t for fermentation.
6) the electron transport chain is where the majority of ATP is generated in aerobic resp, so the yield will be much lower if it doesn’t take place.

45
Q

Explain why glycolysis is the process that continues in anaerobic respiration whereas the link reaction, the Krebs cycle and oxidative phosphorylation all stop.

A

In glycolysis, hydrogen atoms are accepted from NAD which has been regenerated from fermentation so the glycolysis can continue.
In the link reaction and kreb cycle, NAD and FAD cannot act as coenzymes because they have not been oxidised (regenerated) by the electron transport chain so the processes stop.
In oxidative phosphorylation, the electron transport chain has stopped because there is no oxygen to act as a final electron acceptor.

46
Q

Explain why the regeneration of NAD is the crucial part of either form of fermentation.

A

Because regenerated NAD is needed for glycolysis to continue.

47
Q

Describe how the rate of anaerobic respiration and aerobic respiration can be measured in yeast.

A

Anaerobic Respiration

1) Measure the volume of CO2 released.
2) Seal respiratory substrate and yeast in a flask so that anaerobic conditions are ensured.
3) Use a gas syringe to measure the volume of CO2 produced in a given time.

Aerobic Respiration

48
Q

Define the term “respiratory substrate”.

A

Organic molecules broken down in respiration.

49
Q

Define the terms “relative energy value”.

A

The energy liberated in aerobic respiration?

50
Q

Describe how triglycerides are used in respiration.

A

1) Triglycerides are hydrolysed into fatty acids and glycerol.
2) Glycerol is first converted to pyruvate. The oxidative decarboxylation, producing an acetyl group which combines with coenzyme A, forming Acetyl CoA.
3) Fatty acids are converted into acetyl groups by beta-oxidation. These also combine with coenzyme A to form CoA.
4) The fatty acids in a triglyceride molecule can make up to 50 acetyl CoA molecules. This produces 500 ATP.

51
Q

Describe how proteins are used in respiration.

A

1) Proteins first have to be hydrolysed to amino acids and then have the amine group removed before they can enter the respiratory pathway.
2) These steps require ATP, reducing the net production of ATP.

52
Q

Define the term “respiratory quotient (RQ)” and write the equation for the respiratory quotient.

A

Respiratory quotient is the ratio of carbon dioxide produced to oxygen used in aerobic respiration.

Equation:
RQ = CO2 produced/ O2 consumed.

53
Q

State the typical respiratory quotients for carbohydrates, proteins and lipids.

A 
Carbohydrate = 1.0
Protein = 0.9
Lipids = 0.7
54
Q

Explain the difference in relative energy values between carbohydrates, lipids and proteins.

A

1) Lipids contain a greater proportion of carbon-hydrogen bonds than carbohydrate which is why they produce so much more ATP in respiration.
2) Due to the greater number of carbon-hydrogen bonds, lipids require more oxygen to break them down and release less CO2.
3) This results in RQs of less than 1 for lipids.
4) The structure of amino acids leads to RQs of somewhere between carbohydrates and lipids.
5) It takes 6 oxygen molecules to completely respire 1 molecule of glucose and this results in the production of 6 molecules of CO2. Therefore, the RQ is 1.

55
Q

Describe how a respirometer can be used to provide information about which respiratory substrate might be being used by an organism at a particular point, and explain why there may be alternative explanations for an organisms RQ value. (F)

A

1) During normal activity, the RQ is in the range of 0.8 to 0.9.
2) This range could include carbohydrates, lipids and some proteins.
3) During anaerobic respiration, the RQ increases above 1.0. Though this is not easy to measure because the exact point that anaerobic resp starts is unclear.

56
Q

Describe a step by step method to investigate the effect of one factor (temperature, substrate concentration, or different respiratory substrate) on the rate of respiration.

A

1) Use a respirometer.
2) The potassium hydroxide solution in the apparatus absorbs CO2 so if the temperature is kept the same, any changes in the volume of air in the respirometer will be due to oxygen uptake.
3) You can set up different respirometers with different conditions.
4) Measure the distance the coloured liquid moves in the graduated tube after being left for 20 mins.

Biology (35 decks)

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