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Alevel Biology OCR > 5.2.2 - Respiration > Flashcards

5.2.2 - Respiration Flashcards

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1
Q

What is respiration?

A

a process where glucose is broken down to release energy (generated in the form of ATP)

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2
Q

What is the equation for respiration?

A

glucose + oxygen -> carbon dioxide + water

C6H12O6 + 6O2 -> 6CO2 + 6H2O

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3
Q

Why is cellular respiration needed?

A 
to produce ATP for processes like...
-active transport
-photosynthesis
-cell division
-movement of vesicles
-phagocytosis
etc
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4
Q

Describe the structure of a mitochondrion

A
  • double membrane where inner mitochondrial membrane is folded to form cristae
  • matrix containing mitochondrial DNA and ribosomes (needed for protein synthesis to make any enzymes needed)
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5
Q

Where does glycolysis occur?

A

cytoplasm

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6
Q

What is glycolysis?

A

the breakdown of glucose into pyruvate

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7
Q

What are the products of glycolysis (per one molecule of glucose)?

A

2x pyruvate
2x ATP
2x redNAD

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8
Q

What happens during glycolysis?

A 
glucose
glucose phosphate
fructose phosphate
fructose bisphosphate
2x triose phosphate
2x triose bisphosphate
2x triose phosphate
2x pyruvate
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9
Q

Where does the link reaction occur?

A

matrix of mitochondria

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10
Q

What is the link reaction?

A

the conversion of pyruvate into acetyl coA

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11
Q

What happens in the link reaction?

A

pyruvate -> acetyl group -> acetyl CoA

  • dehydrogenation (pyruvate looses Hs and NAD gains them so is reduced)
  • decarboxylation (CO2 is lost)
  • coenzyme A added
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12
Q

What are the products of the link reaction (per one molecule of glucose)?

A

2x acetyl CoA

2x redNAD

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13
Q

Where does the Krebs Cycle occur?

A

matrix of mitochondria

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14
Q

What happens in the Krebs Cycle?

A
  • acetyl CoA and OAA forms citrate
  • citrate is decarboxylated (looses CO2) and dehydrogenated (looses H as NAD is reduced) to form a 5C intermediate
  • 5C intermediate is decarboxylated (looses CO2) and dehydrogenated (looses H as NAD is reduced) to form a 4C intermediate
  • 4C intermediate is converted into a different 4C intermediate as ADP is phosphorylated
  • 4C intermediate is converted into another 4C intermediate as FAD is reduced
  • 4C intermediate is converted into oxaloacetate (OAA) as NAD is reduced
  • OAA can be reconverted into citrate, allowing the cycle to continue
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15
Q

What are the products of the Krebs Cycle (per one molecule of glucose)?

A

2x ATP
2x redFAD
6x redNAD

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16
Q

What coenzymes are used in cellular respiration?

A
  • NAD
  • FAD
  • coenzyme A
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17
Q

What is substrate level phosphorylation?

A

phosphorylation when a phosphate group is directly transferred from one molecule to another
eg. during glycolysis and the Krebs Cycle

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18
Q

What is oxidative phosphorylation?

A

phosphorylation when energy from electrons from reduced coenzymes (NAD and FAD) is used to synthesise ATP

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19
Q

Where does oxidative phosphorylation occur?

A

inner mitochondrial membrane (cristae)

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20
Q

What happens in oxidative phosphorylation?

A
  • in the matrix of the mitochondria, redNAD and redFAD are dehydrogenated into NAD and FAD and hydrogen atoms
  • these Hs are dissociated into H+ and e-
  • these e- move down an electron transport chain in the inner mitochondrial membrane, loosing energy as they do so
  • this energy is used by a proton pump move the H+ ions across the inner membrane into the intermembrane space, creating a proton (electrochemical) gradient across the inner membrane
  • the H+ ions then move back across the inner membrane through ATP synthase (known as chemiosmosis)
  • this turns ATP synthase on so that ADP can be phosphorylated into ATP
  • the H+ ions and e- then combine with oxygen (aka the final electron accepter) to produce water (this is catalysed by cytochrome oxidase)
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21
Q

How do metabolic poisons disrupt oxidative phosphorylation?

A
  • they bind to electron carriers, which inhibits the electron transport chain
  • reduces chemiosmosis
  • inhibits Krebs Cycle as NAD and FAD are not regenerated
22
Q

How much ATP is produced across all of aerobic respiration?

A

38

23
Q

Why is less ATP produced than the theoretical maximum?

A
  • some ATP is used for active transport (of pyruvate and H+ ions from glycolysis into the mitochondrion)
  • some energy is released to surroundings (eg. as heat)
  • not all of the H+ ion movement across the membrane is used to generate ATP/goes through ATP synthase (eg. H+ leak through membrane)
  • not all redNAD produced is used to make ATP
24
Q

What are the stages in aerobic respiration?

A
  • glycolysis
  • link reaction
  • Krebs Cycle
  • oxidative phosphorylation
25
Q

What are obligate anaerobes?

A

organisms that only respire anaerobically

eg. prokaryotes like clostridium

26
Q

What are obligate aerobes?

A

organisms that only respire aerobically

eg. mammals

27
Q

What are facultative anaerobes?

A

organisms that can respire both aerobically and anaerobically (depending on the conditions)
eg. yeast

28
Q

What are the two types of anaerobic respiration?

A

lactate fermentation

alcoholic fermentation

29
Q

Where does lactate fermentation occur?

A

cytoplasm of muscle cells

in mammals

30
Q

What happens in lactate fermentation?

A
  • pyruvate is converted into lactate (lactic acid)
  • catalysed by lactate dehydrogenase
  • redNAD is oxidised
31
Q

What happens to the lactate produced from lactate fermentation when there is oxygen again?

A

-lactate is converted back into glucose in the liver

32
Q

Where does alcoholic fermentation occur?

A

yeast

33
Q

What happens in alcoholic fermentation?

A
  • pyruvate is decarboxylated to form ethanal (catalysed by pyruvate dehydrogenase and pyruvate decarboxylase)
  • ethanal is reduced to ethanol (catalysed by ethanal dehydrogenase)
  • redNAD is oxidised
34
Q

What would happen if too much ethanol was produced in alcoholic fermentation?

A

-cell membranes would dissolve in the ethanol

35
Q

Why do organisms respire anaerobically?

A
  • 2xATP are still produced in glycolysis

- NAD is regenerated (which is needed in glycolysis, so allows glycolysis to continue)

36
Q

Why does anaerobic respiration produce less ATP than aerobic respiration?

A
  • ATP is only produced from glycolysis (only 2 molecules of ATP)
  • Krebs cycle, oxidative phosphorylation, etc can’t occur (oxygen is needed as a final electron acceptor)
37
Q

RQ=

A

volume of CO2 produced
____________________
volume of O2 used

38
Q

What molecules are normally used in respiration?

A

carbohydrates and lipids

39
Q

When are proteins used in respiration?

A

during starvation

40
Q

What substrate is being used for respiration if there is a RQ value of 1?

A

carbohydrates

41
Q

What substrate is being used for respiration if there is a RQ value of 0.7?

A

lipids

42
Q

What substrate is being used for respiration if there is a RQ value of 0.8-0.9?

A

proteins
-range because there are different R groups in different amino acids
(or a mixture of carbohydrates and lipids)

43
Q

Why do lipids release more energy than carbohydrates when used as a respiratory substrate?

A
  • lipids have more H atoms
  • so can form more redNAD
  • which forms more ATP
44
Q

What does a RQ value of more than 1 mean?

A

anaerobic respiration is occuring

45
Q

What is a respirometer used for?

A

to find the rate of respiration

-measured the volume of O2 produced/CO2 used

46
Q

What is the function of soda lime in a respirometer?

A

absorbs CO2

47
Q

What is the function of the syringe in a respirometer?

A

used to reset the respirometer at the end of each trial

48
Q

What does it mean when the bubble/coloured liquid in the glass tube of the respirometer moves left?

A
  • more O2 is used than CO2 is produced (in aerobic conditions
  • how much O2 is absorbed (in anaerobic conditions)
49
Q

What does it mean when the bubble/coloured liquid in the glass tube of the respirometer moves right?

A

-more CO2 is produced than O2 is used (in aerobic conditions)

50
Q

What causes the bubble/coloured liquid to move in a respirometer?

A

changes in pressure from O2/CO2 being used/produced

Alevel Biology OCR (26 decks)

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