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Biology Module 5 > Respiration 5.7 > Flashcards

Respiration 5.7 Flashcards

1
Q

what is the need for cellular respiration

A

occurs in living cells, releases energy and makes ATP

for active processes like endo/exocytosis, movement of flagella/cilia and DNA replication

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2
Q

what are anabolic reactions

A

when a large mol is synthesised from smaller ones

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3
Q

what are catabolic reactions

A

hydrolysis of large mol into smaller ones

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4
Q

describe the structure of the mitochondria

A

matrix fluid

outer membrane

inner membrane

intermembrane space

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5
Q

describe the fluid matrix

A

where link reaction and Krebs cycle takes place

contains enzymes and coenzymes FAD and NAD

mitochondrial DNA (codes for enzymes and proteins) and ribosomes

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6
Q

describe the outer membrane

A

contain channel and carrier proteins

controls movement in and out

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7
Q

describe the inner membrane

A

folds to form cristae the site of the ETC

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8
Q

describe the intermembrane space

A

where oxidative phosphorylation occurs

close in contact with the matrix so reduced NAD and FAD can easily deliver H2 to the ETC

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9
Q

what is the first stage of respiration

A

glycolysis

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10
Q

what happens in phosphorylation

A

2 phosphates from 2 ATP used to phosphorylate glucose

creates 1 hexose biphosphate and 2 ADP

hexose biphosphate splits into 2 triose phosphate

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11
Q

what happens in oxidation

A

triose phosphate oxidised and forms 2 pyruvate

NAD gains H+ that TP lost and becomes reduced NAD

4ATP made but 2 used in phosphorylation so net gain of 2 ATP

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12
Q

what is the second stage of aerobic respiration

A

link reaction

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13
Q

what happens in the link reaction

A

in mitochondrial matrix

pyruvate, decarboxylated where 1 C atom removed from pyruvate to form CO2

NAD collects H+ from pyruvate forming acetate and becomes reduced

acetate + coenzyme A forming acetyl coA

no ATP prod.

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14
Q

what is the third stage of aerobic respiration

A

Krebs cycle

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15
Q

what happens in the Krebs cycle

A

acetyl group from acetyl coA + oxaloacetate form citrate

coenzyme A goes back to link reaction

citrate converted to a 5C compound

decarboxylation and dehydrogenation of 5C mol

H+ used to reduce NAD

5C mol converted into 4C compound

decarboxylation and dehydrogenation produces one molecule of reduced FAD and 2 reduced NAD

ATP prod from ADP + Pi

citrate now converted into oxaloacetate

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16
Q

what is substrate level phosphorylation

A

when a phosphate group is directly transferred from one mol. to another

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17
Q

what is the fourth stage of aerobic respiration

A

oxidative phosphorylation

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18
Q

why is oxidative phosphorylation useful

A

energy carried by e- from reduced coenzymes are used to create ATP

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19
Q

what happens in oxidative phosphorylation

A

H2 atom released from reduced FAD and NAD

H2 splits into H+ and e-

e- move along ETC losing energy at each carrier

energy form e- pumps protons from matrix to intermembrane space

conc. of protons is higher in intermembrane space than in matrix

protons move down electrochemical gradient to matrix by ATP synthase

ATP made form ADP + Pi

at end of ETC, protons, e- and O2 combine to form water

O2 is the final e- acceptor

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20
Q

define the chemiosmotic theory

A

process of ATP production caused by the movement of H+ along membrane due to e- moving down ETC

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21
Q

importance of decarboxylation

A

releases CO2 waste product

produces energy to e- carriers to make ATP

connects link reaction to Krebs cycle

22
Q

importance of dehydrogenation

A

transfers e- to carriers like NAD and FAD, reducing them

reduced NAD and FAD transport e- to ETC and energy used to make ATP
occurs throughout respiration

w/o this no high energy e- carriers so ETC doesn’t function and no ATP made

23
Q

importance of NAD

A

e- carrier accepts H+ and becomes reduced

glycolysis: NAD –> NADH

Krebs cycle: NADH from dehydrogenation

ETC: NADH donates e- and produces ATP

24
Q

importance of FAD

A

e- like NAD

Krebs cycle: FAD —> FADH2

ETC: FADH2 donates e- at a lower lvl than NADH and prod ATP

25
Q

importance of coenzyme A

A

carriers and transfers acetyl group

Link reaction: combines w/ acetyl group from pyruvate decarboxylation to form acetyl coA

Krebs cycle: acetyl coA transfers acetyl group into oxaloacetate to form citate

26
Q

importance of substrate level phosphorylation

A

immediate source of energy

in the absence of O2 ETC cant function and can rely entirely on subs-lvl-phosp in glycolysis for ATP

this is important in low O2 environments or during intense exercise

27
Q

what happens if O2 is absent

A

O2 cant act as final e- acceptor

H+ and e- cant make H2O

conc. of H+ in matrix inc

conc. of H+ reduces in inner mitochondrial membrane

oxi-phosp comes to an end

reduced NAD and FAD unable to unload H+ and cant be reoxidised

Krebs and Link reaction stop

28
Q

how is reduced NAD reoxidised for fungi and plants

A

ethanol fermentation pathway

29
Q

describe what happens in the ethanol fermentation pathway

A

every mol of pyruvate from glycolysis is decarboxylated and converted to ethanal using pyruvate decarboxylase

ethanal accepts H2 atoms from reduced NAD and forms ethanol using enzyme ethanol dehydrogenase

NAD reoxidised and can now accept more H2 atoms from TP so glycolysis can continue

30
Q

how is reduced NAD reoxidised in mammals

A

lactate fermentation pathway

31
Q

describe the lactate fermentation pathway

A

pyruvate from glycolysis accepts H2 from reduced NAD

catalysed by enzyme lactate dehydrogenase

pyruvate reduced into lactate

NADH reoxidised so can accept more H2 atoms from TP in glycolysis and can continue to make more ATP needed for muscle contraction in a short period

32
Q

where is lactate produced and where does it go

A

muscle tissue carried in the blood to liver

33
Q

when more O2 is available what can lactate do?

A

converted to pyruvate which can enter the Krebs cycle by Link reaction

recycled to glucose and glycogen

34
Q

what happens if lactate was not removed from muscle tissues

A

pH lowers

inhibits actions of many enzymes in glycolysis and muscle contraction

35
Q

describe the ATP yield from respiration

A

ethanol and lactate dont prod ATP

only allow glycolysis to continue so net gain of 2 ATP can still be made

36
Q

compare the ATP yield in anaerobic and aerobic respiration

A

in anaerobic: glucose only partly broken down so many mol can undergo glycolysis so yield of ATP made per min is very large

however yield of ATP in anaerobic respiration is smaller than aerobic

37
Q

what are respiratory substrates

A

organic mol. that can be broken down to release energy to make ATP

38
Q

describe carbs as a respiratory substrate

A

glucose as main substrate

disaccharides digested into monosaccharides

monosaccharides into glucose by isomerase enzymes

39
Q

what type of carbohydrate do RBC and brain cells use

A

glucose

40
Q

what type of carb do animals and some bacteria use

A

glycogen hydrolysed into glucose for respiration

41
Q

what carbs do plants use

A

starch hydrolysed into glucose for respiration

42
Q

describe lipids as a substrate

A

for muscles

triglycerides hydrolysed to FA and glycerol by lipase

glycerol converted to pyruvate before oxidative decarboxylation to prod an acetyl group picked up by coenzyme A from acetyl coA

43
Q

compare carbs and lipids

A

greater proportion of C-H bonds in FA compared to carbs so prod. more ATP than an equal mass of carbs

lipids store 2x more energy than carbs

44
Q

what is B-oxidation

A

when the FA-coA complex transported to matrix and broken to acetyl coenzyme A

45
Q

describe proteins as respiratory substrate

A

excess AA deaminated in liver from urea and keto acid

keto acid enters respiratory pathway as pyruvate, acetyl coA or krebs cycle acid like oxaloacetic acid

46
Q

how does the energy value for each substrate different

A

differs depending on the availibilty of protons fro chemiosmosis

the more hydrogen atoms a respiratory substrate has the more ATP it can make

47
Q

what is the mean energy value for carbs, lipids and proteins

A

15.8kJg-1
39.4
17.0

48
Q

as H+ combine with oxygen to form H2O….

A

the greater proportion in H in a mol means more O2 needed for respiration

49
Q

what is the respiratory quotient

A

RQ= CO2 prod/O2 consumed

no units bcs its a ratio

50
Q

what is the RQ value used for

A

to deduce the substrate being used for respiration

51
Q

compare the RQ value in aerobic and anaerobic conditions

A

in aerobic (normal) conditions, RQ is 0.8 to 1
if RQ is more than 1, anaerobic respiration is happening bcs more CO2 is prod than O2 consumed

52
Q

what happens when glucose lvls are insufficient

A

proteins used and broken down into AA then undergoes deamination forming keto acids

Biology Module 5 (7 decks)

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