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MICR221 > L8 bacterial aerobic cellular respiration > Flashcards

L8 bacterial aerobic cellular respiration Flashcards

1
Q

breakdown of proteins before entering the TCA cycle

A

protein -> amino acid (using protease)
deamination: NH2 is removed
amino acid is primarily transaminated.
amino group is removed and turned into glutamate
glutamate-> alpha-ketoglutarate (carbon skeleton)
Aketo gets fed into TCA cycle (central pathways)

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2
Q

breakdown of sugars for the TCA cycle

A

starch-> glucose
glucose gets metabolised by glycolysis -> pyruvate
pyruvate goes into TCA cycle

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3
Q

breakdown of lipids to fatty acids

2 ways

A

lipid-> fatty acid-> Acetyl CoA -> CoA enter TCA cycle

lipid-> glycerol -> glycolysis

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4
Q

what do the specilised pathways of molecule breakdown do

A

isolate the conserved carbon backbone so it can go through glycolysis or the TCA cycle

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5
Q

what are the two phases of glycolysis

A

energy investment phase

energy payoff phase

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6
Q

what happens during the energy investment phase

A

2 ATP is used to doubly phosphorylate glucose

6C molecule is cleaved into two 3C chains

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7
Q

what happens during the energy pay off phase

A

the 2, 3C molecules are converted into pyruvate

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8
Q

how many steps and what happens in them during the energy pay off stage

A

2 steps
4 ADP + 4P -> 4ATP
2NAD+ +4 e + 4H+ -> 2 NADH + 2H+

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9
Q

what is the net yield of pyruvate

A 
2ATP
2 pyruvate 
2 H2O
2NADH
(6 precursor metabolites)
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10
Q

what would happen to the pyruvate if E.coli was in a anaerobic environment

A

pyruvate would undergo lactic acid fermentation to produce ATP

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11
Q

what happens to the pyruvate under aerobic conditions

A

undergoes complete combustion to CO2

through TCA acid

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12
Q

what happens to pyruvate during TCA cycle

A

converted into acetyl CoA which produces CO2 and NADH

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13
Q

how many precursor metabolites are produced during TCA cycle

A

4

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14
Q

what does the TCA cycle produce lots of

A

NADH

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15
Q

what is FADH

A

electron carrier of slightly lower potential than NADH

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16
Q

what 4 precursor metabolites are produced

A

acetyl CoA
alpha-ketoglutarate
succinyl-CoA
oxaloacetate

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17
Q

what is used to convert pyruvate to acetyl CoA and what is produced

A

pyruvate dehydrogenase

1 NADH

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18
Q

why does the TCA cycle only occur in aerobic bacteria

A

Because the NADH needs to be converted back using an electron transport train in order to keep functioning

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19
Q

what are the products of 1 full cycle of TCA

A

3 NADH
1 GTP
1 FADH2

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20
Q

what is the yeild from 1 glucose molecule through glycolysis and TCA cycle

A

10 NADH, 2 FADH2, 2 ATP, 2 GTP

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21
Q

what are the two ways bacteria like E.coli can make ATP

A

substrate-level phosphorylation (SLP)

oxidative phosphorylation

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22
Q

what is substrate level phosphorylation

A

makes ATP as a consequence of cytoplasmic reactions (no membrane bound proteins)
-uses cytoplasmic enzymes (pyruvate kinase)

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23
Q

example of substrate level phophorylation

A

PEP-> pyruvate +ATP using pyruvate kinase

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24
Q

why is
PEP-> pyruvate +ATP using pyruvate kinase
favourable

A

the energy of cleaving a P from PEP is more negative than ATP
ATP does not have enough energy to phosphorylate PEP

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25
Q

where is another example of substrate level phosphorylation

A

during the TCA cycle when GDP is turned into GTP

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26
Q

disadvantage of substrate level phosphorylation

A

low efficiency

limited without regenerating NAD+ (fermentation)

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27
Q

advantages of substrate level phosphorylation

A

simpler and not limited by electron acceptor

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28
Q

why is OXPHOS so important

A

recycles all of the NADH and FADH2 from the central pathways

29
Q

what enzyme is involoved in YCA cycle and electorn transport chain

A

succinate

30
Q

what system is used in OXPHOS

A

electron transport chain

31
Q

how much more efficient is OXPHOS than SLP

A

10x more ATP is produced

32
Q

what are the four major components of the electron transport chain of mitochondria

A 
complex I
Complex II: succinate dehydrogenase 
complex III: cytochrome bc  1 
complex IV: cytochrome c oxidase 
ATP synthase
33
Q

what is the gst of the electrorn transport chain

A

oxidises NADH and transport electrons through to pump protons across the membrane

34
Q

what is the electron transport chain limited by?

A

availability of an electron acceptor

35
Q

where do the electrons from the transport chain go?

A

put onto oxygen hence why it is needed

36
Q

order the type of respiration from most to least efficient and yield per glucose molecule

A

aerobic: 38
microaerobic: 15
Anaerobic nitrate: 15
anaerobic fumarate: 12
fermentation Acetyl CoA: 3

37
Q

why is oxygen the best electron acceptor ?

A

it has the lowest redox potential/ most far from NAD

38
Q

features of electron transport chains

A

a membrane
membrane-bound oxidative protein complexes
Co-factors
membrane-bound reductive protein complexes

39
Q

role of a membrane in ETC

A

physical barrier to create conc gradient

40
Q

role membrane-bound oxidative protein complexes in ETC

A

liberate electrons from reducing power and MAY pump H+

41
Q

role of co-factors in ETC

A

transfer electrons between enzymes

42
Q

role of membrane bound reductive protein complexes in ETC

A

finally transfer electrons to terminal electron acceptor MAY pump H+

43
Q

example of a membrane

A

cytoplasmic membrane

44
Q

example of oxidative complex

A

complex I

takes NADH-> NAD+

45
Q

does complex I pump protons?

A

yes

46
Q

does complex II pump protons

A

no

47
Q

what are co factors

A

transfers electrons between enzymes by being reduced and oxidised

48
Q

example of a co factor

A

quinones (ubiquinone + menaquinone)

49
Q

what are quinones

A

conjugates between the electron-donating and electron-accepting reaction

50
Q

example of redcutive protien complex

A

complex III

complex IV

51
Q

what do complex II and IV do?

A

take the ubiquinol (reduced quinone) and oxidise it back to the quinone

52
Q

which two complexes make up the super complex in TB(mycobacteria) bacteria electron transport chain

A

III and IV

53
Q

differences between mitochondrial and bacteria electron transport chain

A

ndh enzyme
complexx III and IV are a super complex
cyd enzyme

54
Q

what enzymes in bacteria electron transport chain reduces NADH

A

complex I

ndh

55
Q

is ndh a proton pump?

A

no

56
Q

what cofactor does bacteria use

A

menaquinone

57
Q

which enzymes do the bacteria electron transport chain have that can use oxygen

A

super complex

cyd

58
Q

is cyd a proton pump

A

no

59
Q

can TB respire without oxygen

A

no

60
Q

what happens when TB doesn’t have oxygen

A

goes into persistance and stops replicating

61
Q

what happens when you starve E.coli of oxygen

A

TCA cycle gets shut down

start to reverse the TCA cycle

62
Q

why does the E.coli TCA cycle operate in reverse under anaerobic conditions

A

E.coli uses fumerate to produce ATP

63
Q

what electron acceptors can E.coli use except O2/ use to respire

A 
fumerate
nitrite
nitrate
DSMO
TMNO
64
Q

what does E.coli do when it runs out of electron acceptors

A

begins fermentation

65
Q

what is made during fermentation that can be used as an electron donor

A

formate

66
Q

what is the key enzyme for aerobic respiration

A

cytochrome bo

67
Q

what is the key enzyme for microaerobic respiration

A

cytochrome bd

68
Q

what is the key enzyme for anaerobic respiration

A 
nitrate reductase
nitrite reducates
fumerate reductase
DMSO reductase
TMAO reductase
69
Q

what are the key enzymes for fermentation

A

lactate dehydrogenase

formate hydrogenlyase

MICR221 (23 decks)

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