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A Level Biology > Respiration > Flashcards

Respiration Flashcards

1
Q

What is respiration?

A

series of metabolic reactions where respiratory substrate molecules are metabolised to produce ATP molecules which can then be hydrolysed to release energy for energy requiring processes in cells

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2
Q

What is a respiratory substrate?

A

any molecule that can be metabolised to produce ATP

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3
Q

Why is glucose not very useful (why does it need to be respired)?

A

1 glucose molecule has a lot of chemical potential energy but not very useful because energy in 1 big package

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4
Q

Why is ATP more useful than glucose?

A
  • around 32 ATP molecules produced by resp

- high energy molecules but much more useful bc energy is in small packages

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5
Q

respiration does not produce…

A

ENERGY, produces ATP

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6
Q

ATP requiring processes e.g.?

A
  • AT
  • muscle contraction
  • protein synthesis
  • cilia movement
  • bulk transport
  • DNA rep
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7
Q

Stages?

A
  1. Glycolysis
  2. link reaction
  3. Krebs cycle
  4. Oxidative Phosphorylation
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8
Q

Glycolysis?

A
  • splitting of glucose

- occurs in aerobic and anaerobic

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9
Q

Size of ribosomes in mitochondria?

A

70s, needed for translation of mitochondrial proteins

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10
Q

Why are there stalked particles in mitochondria?

A
  • all along IMM
  • ATP synthase molecules 1-2micrometer long
  • H+ move through ATP synthase molecules by FD allowing synthesis of ATP
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11
Q

why does mitochondria have DNA?

A

• contains genes for mitochondrial proteins e.g. ATP synthase

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12
Q

cristae in mitochondria?

A
  • folds
  • inc SA
  • for e- carrier proteins - OP
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13
Q

membrane of mitochondria?

A
  • inner membrane
  • intermembranal space
  • outer membrane

envelope

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14
Q

inner mitochondrial membrane?

A
  • folds to inc SA
  • separates intermembranal space from matrix
  • contains membrane proteins involved in OP
  • H+ ion move thru ATP synthase
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15
Q

intermembranal space?

A

provides a space for the build up of a H+ proton gradient

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16
Q

outer mitochondrial membrane?

A

compartmentalises the link reaction, krebs cycke, and OP from cytoplasm of the cell

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17
Q

glycolysis doesn’t occur in?

A

mitochondria, actually occurs in cytoplasm

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18
Q

Steps in glycolysis?

A 
Glucose 
      ⬇ (ATP ➡ ADP + Pi)
hexose phosphate 
      ⬇ (ATP ➡ ADP + Pi)
hexose bisphosphate 
      ⬇
2 TP
      ⬇ (4ADP ➡ 4ATP), (2redNAD produced)
2Pyruvate
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19
Q

Glucose to hexose bisphosphate is

A

phosphorylation

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20
Q

triose phosphate to pyruvate is ?

A

oxidation, (2redNAD produced)

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21
Q

how many ATP needed to start resp

A

2

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22
Q

NAD?

A
  • coenzyme
  • H carrier
  • takes part in reactions catalysed by dehydrogenases (takes H)
  • when it gets reduced, gains 2 H atoms (2H+ + 2e-)
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23
Q

reduction of NAD equation?

A

NAD + 2H+ + 2 e- ➡ NADH + H+

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24
Q

The link reaction?

A
  • happens in matrix

* links glycolysis and krebs cycle

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25
Q

Steps of link reaction?

A 
2 Pyruvate (3C)
        ⬇ (2CO2 removed, decarboxylation reaction)
           (H lost, dehydrogenation)
2 Acetate (2C)
        ⬇ ⬅ coenzyme A 
2 Acetyl coenzyme A 
        ⬇
2 Acetate
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26
Q

what happens to acetate?

A

combines with the coenzyme A (upwards arrow), fed into KC

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27
Q

How many acetates from 1 pyruvate?`

A

1

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28
Q

H that are lost are used to

A

reduce NAD

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29
Q

KC a.k.a

A

citric acid cycle or TCA

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30
Q

What enters the krebs cycle?

A
  • acetyl coA combines with oxolacetate (4C)
  • forming citrate (6C)
  • goes off to collect more acetate
  • Citrate then decarboxylated and dehydrogenated (oxidised)
  • H combine with NAD to form redNAD and FAD to form redFAD
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31
Q

KC summary - per 1 turn ?

A
  • 3 redNAD
  • 2 CO2 produced
  • 1 ATP
  • redFAD
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32
Q

ATP produced from glycolysis and KC is

A

substrate level phosphorylation, OP contrasts

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33
Q

⭐ 2 TURNS OF KC PER

A

1 GLUCOSE

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34
Q

OP?

A
  • ETC
  • located within mitochondrial membrane, happens in IMM, IMS and matrix
  • where the most energy required
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35
Q

OP?

A
  • redNAD and redFAD give up their H to the ETC where the H are split into H+ + e- using energy from e- movement
  • H+ are pumped (not AT) into IMS
  • more H+ in IMS = diffusion gradient
  • H+ move into matrix through ATP synthase, producing ATP
  • -chemisosmosis
  • O2 accepts e- from ETC - final electron acceptor
  • O- + 2H+ -> H2O
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36
Q

OP is not?

A

substrate level phosphorylation

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37
Q

OP - if O is not available?

A
  • If O2 not avbl to collect e-, e- is stuck
  • traffic jam queue of NAD and FAD waiting to drop off H+
  • causes shortage for krebs cycle
  • prevents other stages
38
Q

why do we not achieve the potential yield of ATP molecules?

A
  • only get potentials if enough ADP + Pi in mitochondria

* 25% of ATP made is used to transport ADP into mitochondria and ATP out into cell

39
Q

how many ATPs produced in OP?

A

• 28, 32 in total from resp - 2 gained in KC and 2 in Gly

40
Q

How many turns of KC for every glucose ?

A
  • 2
  • Glycolysis: 2 molecules of pyruvate formed
  • make 2 molecules of acetyl coA
  • so, for each molecule of glucose, 2 turns of krebs cycle
41
Q

Other reasons why max theoretical yield of glucose of not achieved ?

A
  • 38
  • pyruvate has to be AT from cytoplasm into matrix
  • ADP and Pi have to be AT from cytoplasm into matrix
  • some H+ leak across IMM back into matrix
42
Q

H+ ion movement thru ATP synthase is?

A

facilitated diffusion

43
Q

Evid for chemisosmosis?

A
  1. pH gradient, high in matrix - chemiosmosis
  2. dinitrophenol causes IMM to be very leaky to H+. Mit treated with DNP produce less ATP - H+ can bypass ATP synthase so less ATP made
  3. isolated thylakoids can be made to produce ATP
44
Q

When there’s no O2?

A
  • O cannot accept electron
  • so ETC stops
  • redNAD can’t be reoxidised so
  • Krebs cycle stops
  • pyruvate not made so acetyl coA not made
45
Q

Why should glycolysis no longer continue?

A

• redNAD made can no longer release H and be recycled

46
Q

2 pathways of anaerobic resp?

A
  • ethanol pathway (yeast and some bacteria)

* lactate pathway

47
Q

Ethanol pathway?

A
  • 2 pyruvate produced in pyruvate
  • 2Pyruvate decarboxylated into 2 Ethanal by pyruvate decarboxylase
  • Ethanal reduced from ethanal into 2 ethanol by ethanol dehydrogenase
  • redNAD to oxNAD - oxNAD regen so glycolysis can continue
48
Q

ethanol pathway - ATP yield & plants?

A
  • low ATP yield

* occurs in waterlogged plants bc they’re O2 deprived

49
Q

lactate pathway?

A
  • all mammals
  • only 2 mols of ATP produced
  • glycolysis continues
  • but pyruvate is reduced to lactate generating oxNAD so glycolysis can continue
50
Q

what happens to pyruvate in lactate pathway?

A

Pyruvate ➡ lactate by lactate dehydrogenase

oxNAD made

51
Q

in both anaerobic systems ?

A
  • there is a toxic build up

* if toxic levels of ethanol, reaction can be reversed

52
Q

how do we deal w lactate?

A
  • travels in blood to liver
  • where it’s combined with O2 (the oxygen debt!) to form CO2 and H2O - 20% oxidised
  • lactate to pyruvate in liver
  • if there’s a lot: pyruvate ➡ glucose➡glycogen
53
Q

which reactions happen to keep glycolysis going?

A
  • mammals: lactate pathway

* yeast: ethanol pathway

54
Q

what are the disadvantages of anR comp to AR?

A
  • lactate and ethanol r toxic
  • lactate causes pain, can’t happen for long
  • ethanol kills yeast cells if closed envir
  • 2 ATP produced in lactate
55
Q

what happens to the lactate when ATP demand returns to a level where it can be met by AR?

A
  • lactate ➡ pyruvate in the liver
  • pyruvate enters link reaction
  • pyruvate can b converted to glycogen for storage
56
Q

Removal of lactate also needs?

A
  • to become oxidised back to pyruvate, lactate also needs oxNAD to be reduced
  • oxNAD supplied by OP when AR restarts
57
Q

What is a resp substrate?

A

substance used to produce ATP in a cell by respiration

58
Q

How can triglycerides be respired?

A
  • hydrolysed to FA
  • which enters KC via acetyl coA
  • and glycerol which ➡ pyruvate
59
Q

lipids & resp?

A

lipids store and release about 2x as much energy as carbs

60
Q

how can proteins be respired?

A
  • proteins are hydrolysed to AA
  • AA have to be deaminated at hepatocytes - ornithine cycle
  • requires ATP, reducing net ATP production
61
Q

how is RQ measured?

A

using a respirometer

62
Q

Where does each RS enter resp?

A
  • glycerol in TP (gly)
  • FA in acetyl coA
  • lactate at pyruvate
  • AA from proteins at pyruvate or KC
63
Q

energy content in decreasing order?

A

lipids > alcohol > carbs/ proteins

64
Q

oxidation involves ?

A

dehydrogenation - loss of H atoms

65
Q

why do different RS have diff energy densities?

A
  • ATP is obtained from RS thru oxidation forminh redNAD
  • involves dehydrogenation
  • if a molecule has proportionally more H atoms, then more redNAD molecules are formed and more ATP molecules can be synthesised in OP
  • also means more O2 needed to accept e-s at the end of ETC - so lipids have RQ of >1
66
Q

What can the RQ value show?

A
  • what is being respired

* whether or not anR is occuring

67
Q

RQ equation?

A

vol of CO2 out (in a set time)/ vol of O2 in (in a set time)

68
Q

RQ values ?

A

carbs: 1
protein: 0.8-0.9
lipids: 0.7

69
Q

RQ general?

A
  • can be volume, n, molecules

* if RQ values are high, more CO2 is being produced than O2 is being used, indicating high levels of anR

70
Q

if RQ is over 2 ?

A
  • ethanol pathway

* some O2 in the yeast may be taken up

71
Q

RQ for lactate pathway?

A

• can’t calc

72
Q

Why is the RQ for complete anR of glucose in yeast infinite?

A

2CO2 produced but none used -2/0 = infintity

73
Q

why can the RQ for anR of glucose in humans can’t be calc?

A

no O2 used and no CO2 produced

74
Q

Respirometer: bubble movement?

A
  • when O2 taken in, would move ⬅ towards the thing

* when CO2 exhaled (more than taken in) moves ➡

75
Q

when something is respiring (taking in O2) as much as it is exhaling CO2?

A

• bubble would move the same amount in each direction so no overall movement: RQ is 1

76
Q

respirometer: why does the exp need to be done 2x?

A
  • with KOH/ sodalime - absorb CO2
  • more movement towards organism
  • record movement - will tell us the O2 consumption
  • repeat w/o absorber - to get CO2 production along (minus the values)
77
Q

if RQ is >1?

A

could be respiring anR, producing more CO2 than O2 consumption

78
Q

Glycolysis is?

A

substrate level phosphorylation

79
Q

Why is ATP needed in glyolysis?

A
  • addition of phosphate group to glucose destabilises glucose bc P = polar which makes it more likely to undergo the following reactions
  • glucose = stable so ATP needed
80
Q

what is the point of the KC?

A

To make red coenzymes

81
Q

KC products?

A
  • 3redNAD, 1red FAD for acetyl

* 6 redNAD, 1 redFAD, 1 ATP per glucose

82
Q

if ETC stops, how are other stages affected?

A
  • NADH and FADH build up
  • this is bc they can’t give up e- bc the 1st e- carrier is already occupied w e-
  • means no oxNAD and oxFAD regen
  • so KC will stop ^ are needed there
  • link reaction stops - needs NAD and coA
  • glycolysis continues
83
Q

when the coenzymes are reoxidised in OP?

A

can go back to KC and accept more H+.

84
Q

Respirometer: why is a gauze platform used?

A

• stops organisms from falling into the liquid

85
Q

Respirometer: why is a screw clip used?

A

seal apparatus

86
Q

Respirometer: why is a syringe used?

A

to reset position of liquid in capillary tube

87
Q

Respirometer: 3 way tap?

A

• to top up O2 to inc volume

88
Q

Respirometer: why are glass beads used in the control tube?

A

to ensure exactly the same V as respiring organisms

89
Q

Respirometer: why is a capillary U tube used?

A

to measure CO2 production and O2 consumption

90
Q

Respirometer: why is a control tube used?

A
  • Cancels out the effect of temp in respirometer
  • same V of air in each tube because same vol of organisms and beads
  • so if T inc, air inside both tubes expands so the liquid is pushed up and down by the same degree - doesn’t move
91
Q

effect of T on respirometer?

A
  • causes gas to expand
  • which causes the movement of fluid
  • but fluid should only move due to O2/ CO2

A Level Biology (28 decks)

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