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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
where is another example of substrate level phosphorylation
during the TCA cycle when GDP is turned into GTP
26
disadvantage of substrate level phosphorylation
low efficiency | limited without regenerating NAD+ (fermentation)
27
advantages of substrate level phosphorylation
simpler and not limited by electron acceptor
28
why is OXPHOS so important
recycles all of the NADH and FADH2 from the central pathways
29
what enzyme is involoved in YCA cycle and electorn transport chain
succinate
30
what system is used in OXPHOS
electron transport chain
31
how much more efficient is OXPHOS than SLP
10x more ATP is produced
32
what are the four major components of the electron transport chain of mitochondria
``` complex I Complex II: succinate dehydrogenase complex III: cytochrome bc 1 complex IV: cytochrome c oxidase ATP synthase ```
33
what is the gst of the electrorn transport chain
oxidises NADH and transport electrons through to pump protons across the membrane
34
what is the electron transport chain limited by?
availability of an electron acceptor
35
where do the electrons from the transport chain go?
put onto oxygen hence why it is needed
36
order the type of respiration from most to least efficient and yield per glucose molecule
aerobic: 38 microaerobic: 15 Anaerobic nitrate: 15 anaerobic fumarate: 12 fermentation Acetyl CoA: 3
37
why is oxygen the best electron acceptor ?
it has the lowest redox potential/ most far from NAD
38
features of electron transport chains
a membrane membrane-bound oxidative protein complexes Co-factors membrane-bound reductive protein complexes
39
role of a membrane in ETC
physical barrier to create conc gradient
40
role membrane-bound oxidative protein complexes in ETC
liberate electrons from reducing power and MAY pump H+
41
role of co-factors in ETC
transfer electrons between enzymes
42
role of membrane bound reductive protein complexes in ETC
finally transfer electrons to terminal electron acceptor MAY pump H+
43
example of a membrane
cytoplasmic membrane
44
example of oxidative complex
complex I | takes NADH-> NAD+
45
does complex I pump protons?
yes
46
does complex II pump protons
no
47
what are co factors
transfers electrons between enzymes by being reduced and oxidised
48
example of a co factor
quinones (ubiquinone + menaquinone)
49
what are quinones
conjugates between the electron-donating and electron-accepting reaction
50
example of redcutive protien complex
complex III | complex IV
51
what do complex II and IV do?
take the ubiquinol (reduced quinone) and oxidise it back to the quinone
52
which two complexes make up the super complex in TB(mycobacteria) bacteria electron transport chain
III and IV
53
differences between mitochondrial and bacteria electron transport chain
ndh enzyme complexx III and IV are a super complex cyd enzyme
54
what enzymes in bacteria electron transport chain reduces NADH
complex I | ndh
55
is ndh a proton pump?
no
56
what cofactor does bacteria use
menaquinone
57
which enzymes do the bacteria electron transport chain have that can use oxygen
super complex | cyd
58
is cyd a proton pump
no
59
can TB respire without oxygen
no
60
what happens when TB doesn't have oxygen
goes into persistance and stops replicating
61
what happens when you starve E.coli of oxygen
TCA cycle gets shut down | start to reverse the TCA cycle
62
why does the E.coli TCA cycle operate in reverse under anaerobic conditions
E.coli uses fumerate to produce ATP
63
what electron acceptors can E.coli use except O2/ use to respire
``` fumerate nitrite nitrate DSMO TMNO ```
64
what does E.coli do when it runs out of electron acceptors
begins fermentation
65
what is made during fermentation that can be used as an electron donor
formate
66
what is the key enzyme for aerobic respiration
cytochrome bo
67
what is the key enzyme for microaerobic respiration
cytochrome bd
68
what is the key enzyme for anaerobic respiration
``` nitrate reductase nitrite reducates fumerate reductase DMSO reductase TMAO reductase ```
69
what are the key enzymes for fermentation
lactate dehydrogenase | formate hydrogenlyase

MICR221 (23 decks)

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