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CCEA A2 Biology Unit 2 > U2T1 - Respiration > Flashcards

U2T1 - Respiration Flashcards

Respiration

1
Q

What is the equation for aerobic respiration?

A

Glucose + oxygen -> carbon dioxide + water + energy

C6H12O6 + 6O2 -> 6CO2 + 6H2O + ATP

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2
Q

How does respiration occur?

A

Series of enzyme controlled steps so energy release controlled.

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3
Q

How is ATP synthesised?

A

From ADP + inorganic phosphate (Pi) during phosphorylation, making ATP energy rich with extra phosphate group. By substrate level or oxidative phosphorylation. Uses condensation (removes 1 molecule water). To convert back, use hydrolysis (use water, catalysed by ATPase)

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4
Q

Describe the conversion of ATP to ADP and ADP to AMP.

A

They yield same amount of energy as breakage of bond between single remaining phosphate + sugar yields very little energy. Done by ATPase. Reversible but requires energy.

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5
Q

How much ATP do cells store?

A

Very little. Max 5g in body at any time. Rapidly built from ADP + Pi so continual cycling in cells.

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6
Q

Why is ATP a suitable energy store?

A

Hydrolysis of ATP molecules releases small amount of energy compared to glucose so can be released in small, manageable steps. ATP hydrolysis is single reaction (1 bond broken) which releases energy immediately + provides cell fine control over energy. ATP small + soluble so can be transported around cell easily.

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7
Q

What are some uses of ATP?

A

Energy for metabolic processes, movement, active transport + activates molecules via phosphorylation (glycolysis).

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8
Q

Describe the structure of the mitochondria.

A

Surrounded by double membrane separated by inter-membrane space, outer membrane permeable to most small molecules, inner membrane highly folded forming cristae which increase SA for more ATP. Enzymes for ETC on cristae. Matrix contains chem compounds + some resp reactions occur there.

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9
Q

What are the stages of aerobic respiration?

A

Gycolysis, link reaction (pyruvate oxidation), kreb’s cycle + ETC (Electron transport chain)

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10
Q

Describe the process of glycolysis.

A

Activate glucose by phosphorylation, make more reactive + uses ATP as 2 phosphates come from hydrolysis of 2 ATP molecules, cerates fructose 1,6 biphosphate.
Splits into 2 3-carbon molecules of triose phosphate, oxidised by H2 loss using dehydrogenation by dehydrogenase to form pyruvate with production of 2 ATP molecules. H2 atoms collected by NAD which reduces them to NADH. At end, glucose - 2 pyruvate results in 4 ATP created + 2 NADH + H+. Uses 2 ATP so net gain ATP is 2.

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11
Q

What is the process of the link reaction?

A

Pyruvate decarboxylated by removal of 1 molecule of CO2. Dehydrogenation occurs with H2 removal, forming NADH. 2 carbon acetyl group combines with CoA, forming acetyl CoA. 2 carbon acetyl group enters Kreb’s cycle whilst CoA recycled to be combined with another acetyl group.

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12
Q

What are other names for the Krebs cycle?

A

Tricarboxylic acid cycle (TCA) + citric acid cycle.

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13
Q

Where does the Krebs cycle take place?

A

Mitochondrial matrix. Involves cyclical series of reactions.

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14
Q

Describe the process of the Krebs cycle.

A

2C Acetyl CoA combines with 4C oxaloacetate forming 6C citric acid/citrate which undergoes decarboxylation, forming 5C oxoglutarate, losing 1 molecule CO2. Dehydrogenation also occurs, H2 reduces NAD to NADH. Oxoglutarate decarboxylated, forming 4C oxaloacetate, losing CO2 + cycle continues. Converting 5C Oxo to 4C Oxa involve dehydrogenation so at 2 points occurs so 2 molecules NADH produced. At 1 point, hydrogen released + used by FAD, reducing it to FADH2.

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15
Q

What is produced by the Krebs cycle?

A

As 2 molecules Acetyl CoA for each glucose molecule, cycle turns twice for each molecule so for each molecule, cycle produced 2 molecules of ATP directly, 6 pairs H2 atoms for 6 molecules NADH + 2 pairs H2 atoms forming 2 molecules FADH2.

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16
Q

Where does the ETC occur?

A

Cristae of mitochondria.

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17
Q

Why is the ETC diagram drawn as sloping?

A

As throughout chain, electrons lose potential energy as it’s converted into chemical energy in form of ATP. NAD, FAD, coenzymes + carriers arranged into sequence of decreasing potential energy, each carrier downstream has stronger reducing power than one before so H2 + electrons can move along chains with carriers reduced + oxidised as H2/e+ pass along chain in redox reactions.

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18
Q

Describe the process of the ETC.

A

NAD + FAD feed in pairs of H2 from link, krebs + glyco. H atoms split into protons + electrons between CoA Q + Cyto B. NAD passes in H atoms earlier than FAD which feeds in between flavoprotein + cyto Q. H2 dissociates into electrons (2e-) + protons (2H+) so ETC functions as electron carrier. O2 acts as final acceptor of H atoms + combines with H2 (e- + h+ rejoin) to form water, catalysed by cytochrome oxidase. As H atoms released from carriers (FAD + NAD), carriers regenerated to return to glycolysis + so on.

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19
Q

What is interesting about the cytochromes involved in the ETC?

A

Contain iron, electrons go to cytochromes, hence why you can become breathless when anaemic.

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20
Q

At what stage is O2 needed for respiration? What is the only stage which can occur without it?

A

ETC (acts as final acceptor)

Glycolysis

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21
Q

What increases the amount of ATP produced from the ETC?

A

Higher surface area due to more deeply folded cristae as more space for electrons + coenzymes etc.

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22
Q

What is the total number of ATP formed at each stage of respiration? Which is highest?

A

Glyco - 2 (substrate)
Link - 0
Krebs - 2 (substrate)
ETC - 34 (oxidative)

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23
Q

How much ATP is theoretically + realistically produced during respiration + why are these values different?

A
  1. 30 - 36.
    NADH from glycolysis can’t enter mitochondrion easily so passes electron onto FAD molecule which then enters ETC. NADH probably produces 2.5 ATP’s and FADH 1.5 ATP’s.
24
Q

What other substrates can be used in respiration?

A

Glucose, fat, protein. When triglycerides hydrolysed into fatty acids + glycerol, glycerol enters at glycolysis + fatty acids enter at krebs cycle. Other carbs also. Many enter at acetyl CoA stage.

25
Q

What happens to fatty acids when they enter the respiratory chain at the krebs cycle?

A

Undergo beta oxidation. Can yield lots of ATP. Triglycerides are energy rich.

26
Q

What happens to proteins in the respiratory chain?

A

Hydrolysed into amino acids. After amino group removed by deamination, residue enters cycle as acetyl CoA (majority), pyruvate or intermediate compound of krebs cycle.

27
Q

What can still happen during anaerobic respiration?

A

Glycolysis. No other parts of the respiratory chain. Only 2 ATP molecules produced here. Also 2 pairs of hydrogen atoms which possess lots of free energy (normally passed to NAD). Energy can’t be released without O2 but H2 must be removed for glycolysis to continue so they’re combined with pyruvate to form ethanol/lactate by fermentation. Doesn’t yield energy, just mops up excess hydrogen ions. All occurs in cytoplasm + quite fast. Only done for short time period.

28
Q

Why does anaerobic respiration occur in healthy mammals?

A

Skeletal muscles due to strenuous exercise. Muscles respire aerobically + anaerobically at this time. Provides extra energy (escape from predator/win race). Lactate produced causes muscle fatigue + cramps. Need O2 to convert back to glucose/metabolised.

29
Q

What is the equation for anaerobic respiration in animals?

A

Glucose -> lactate + energy

C6H12O6 -> 2C3H6O3 + energy

30
Q

What is the equation for anaerobic respiration in plants + fungi?

A

Glucose -> ethanol + carbon dioxide + energy

G6H12O6 -> 2C2H5OH + 2CO2 + energy

31
Q

Describe anaerobic respiration in plants + fungi.

A

CO2 released as waste product + ethanol eliminated as waste product. Have lower metabolic rate so can respire anaerobically for longer with fewer issues.

32
Q

What is the equation for RQ?

A

RQ = Vol (molecules) of CO2 released/Vol (molecules) of O2 consumed.

33
Q

What is the RQ value of glucose?

A

6/6 = 1

34
Q

What are the RQ values of carbs, proteins + lipids?

A

1, 0.9, 0.7.

35
Q

What is the RQ for just anaerobic respiration?

A

Infinity

36
Q

What is the average RQ for human?

A

0.85

37
Q

What does an RQ of less than 1 suggest?

What does an RQ of more than 1 suggest?

A

Some carb + lipids respired.

Anaerobic resp. Higher = more anerobic resp.

38
Q

What is the equation to calculate volume for a respirometer? (so can calc RQ)

A

V = pi x r2 x h

39
Q

How do you obtain a value for amount of CO2 produced using a respirometer?

A

Replace potassium hydroxide with water.

40
Q

How do you obtain a value for amount of O2 consumed using a respirometer?

A

Potassium hydroxide in tubes.

41
Q

If no change in liquid movement in manometer, what can we say?

A

Vol of CO2 produced same as O2 absorbed. CO2 produced replaces O2 used so gas volume same.

42
Q

What is the control tube in a respirometer for?

A

Glass beads fill tube to same volume as respiring organism in other tube.

43
Q

What should be done to ensure the respirometer experiment is reliable?

A

Repeat, temp controlled water bath so minimal changes in pressure + vol within tube which could cause air in U-tube to expand/contract, varying results.

44
Q

What does KOH do?

A

Absorbs CO2.

45
Q

Describe how the respirometer works when filled with KOH?

A

As organism respires, uses O2 + releases CO2. As CO2 absorbed, KOH moves towards organism (pressure drops in their tube). Distance moved in given time can be used to estimate rate of resp + amount of O2 used.

46
Q

What reaction creates the 6 molecules of CO2 in respiration?

A

Decarboxylation in krebs cycle + link reaction.

47
Q

How would O2 availability limit activity of krebs cycle?

A

Need oxidised carriers but not available as can’t unload hydrogen so couldn’t occur.

48
Q

How can a mammal physiologically maximise ATP production from aerobic resp?

A

O2 dissociation curve + bohr shift.

49
Q

Why can anaerobic resp only use glucose as resp substrate?

A

Need glucose for glycolysis to occur which is the only stage of respiration which can be carried out without oxygen.

50
Q

Most ATP is made in respiration, where does the rest come from?

A

Light dependent stage of photosynthesis.

51
Q

What is done before anaerobic respiration will occur?

A

Animal physiologically maximises ATP production from aerobic by increasing breathing + heart rate so they get as much oxygen in as possible.

52
Q

What can you assume if an RQ is more than 1?

A

It is probably a plant or fungus as their anaerobic resp doesn’t produce CO2.

53
Q

In respiration, how many ATPs do NADH + FADH yield each?

A

NADH yields 3 whilst FADH yields 2.

54
Q

Why would you put a Respirometer in a water bath for 10 minutes before using?

A

Allow temp to get up to required temp and allow for animal/plant to respire at the required temp.

55
Q

Explain the processes by which NADH is oxidised under anaerobic conditions in mammalian tissue?

A

Lactate produced by oxidising NADH and giving it’s hydrogen to pyruvate.

CCEA A2 Biology Unit 2 (16 decks)

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