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MICR221 Lectures 1-38 > MICR221 Lecture 8 - Principles Of Bacterial Aerobic Cellular Respiration > Flashcards

MICR221 Lecture 8 - Principles Of Bacterial Aerobic Cellular Respiration Flashcards

1
Q

what is converted to form NADH?

A

food sources

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2
Q

what is cell metabolism?

A

taking everything down to a conserved backbone that allows conserved pathways to be operated on meaning that it will not have to produce lots of different proteins

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3
Q

what is the function of specialised pathways?

A

to isolate the conserved carbon backbone from molecules so it can either enter into glycolysis or the CAC

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4
Q

how many carbon rings do sugars/monosaccharides contain?

A

6 carbon rings only

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5
Q

what are sugars/monosaccharides converted to?

A

converted to glucose-6-phosphate or early precursors of glycolysis

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6
Q

what is the relationship between entry into the CAC and an amino acid with a removed amino (NH2) group

A

the amino (NH2) group must be removed to have variable entry into the CAC

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7
Q

what can NH2 be converted to?

A

converted into glutamate

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8
Q

what can glutamate be converted to?

A

can be converted to alpha-ketoglutarate

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9
Q

what is the relationship between alpha-ketoglutarate and the CAC?

A

alpha-ketoglutarate is key in the CAC as it determines the overall rate of the CAC

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10
Q

what is the conversion of glutamate to alpha-ketoglutarate regulated by?

A

the process is tightly regulated by both the CAC and the urea cycle

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11
Q

what is the purpose of deamination?

A

removes excess amino groups (NH2)

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12
Q

can the process of glutamate conversion to alpha-ketoglutarate be reversed?

A

yes it can be reversed

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13
Q

what are fatty acids?

A

glycerol

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14
Q

when does glycerol enter glycolysis?

A

glycerol enters the later stages of glycolysis with only 2 enzyme reactions

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15
Q

what is the relationship between when a molecule enters a pathway and energy investment?

A

if a molecule enters later in a pathway then they can only get the benefits/products from when they entered the pathway but this means the molecule requires a lower energy investment to enter

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16
Q

what is beta-oxidation?

A

the flexible removal of acetyl-CoA or jpropionyl-CoA from any length fatty acid depending on if the chain is odd or even numbered. Both of these molecules can enter the CAC

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17
Q

what are the 2 phases of glycolysis?

A

energy investment phase

energy payoff phase

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18
Q

what is the energy investment phase of glycolysis?

A

ATP is used to further phosphorylate sugar so it forms an unstable intermediate. The 6C sugar ring is then broken down in 2 3C chains that go through the glycolysis cycle twice more

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19
Q

what is energy payoff phase of glycolysis?

A

the production of ATP and NADH from oxidations and the eventual removal of phosphate

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20
Q

how many molecules of pyruvate are produced for each molecule of glucose?

A

2 pyruvate for each molecule of glucose

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21
Q

what is the catabolic process to produce NADH?

A

1) the 2 pyruvate are entered into the CAC and the cycle moves in the forward direction
2) acetyl-CoA is added in and bound to the conserved intermediates (carbons are added on these 4C molecules and they are later removed to generate NADH at the same time)

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22
Q

what are many of the catabolic reactions to produce NADH driven by?

A

driven by dehydrogenase

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23
Q

what is the favourable reaction direction aerobically?

A

aerobically the favourable direction is oxidative –> forward cycle

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24
Q

what is the function of dehydrogenase?

A

performs oxidation reactions that can produce a lot of energy currencies

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25
Q

what are the 2 major routes of ATP production?

A

substrate level phosphorylation

oxidative phosphorylation

26
Q

what is substrate level phosphorylation?

A

makes ATP as a consequence of cytoplasmic reactions such as glycolysis and the CAC. It is low efficiency but is simple and not limited by electron acceptor although it is eventually limited without regenerating NAD+ (e.g fermentation). Low amounts of ATP are produced but smaller amounts of proteins are made

27
Q

what are fermenters?

A

bacteria that have evolved to make ATP purely from cytoplasmic substrate level phosphorylation

28
Q

what do cytoplasmic reactions require?

A

require NAD+ to drive redox reactions and oxidise glucose

29
Q

what is oxidative phosphorylation?

A

uses reducing powers to generate ATP and the ETC + ATP synthase also. It is high efficiency but complex and limited by the electron acceptor but regenerates NAD+. It is linked by PMF also known as cellular respiration

30
Q

what are the reducing powers of oxidative phosphorylation?

A

FADH2 and NADH

31
Q

what establishes the concentration gradient for oxidative phosphorylation?

A

electrons that are put onto oxygen

32
Q

what is oxidative phosphorylation good for in terms in types of organisms?

A

good for organisms that need to produce lots of ATP (fast growth rates or need to use their carbon sources more efficiently for persisters and slow growing cells)

33
Q

how does oxidative phosphorylation compare with substrate level phosphorylation in terms of the amount of ATP produced?

A

oxidative phosphorylation produces up to 10 times more ATP than substrate level phosphorylation because the presence of oxygen hugely impacts ATP yields

34
Q

what processes is ATP required for?

A

anabolic processes like polymer synthesis

35
Q

what does the growth of bacteria depend on in terms of ATP?

A

growth of bacteria depends on ATP yields

36
Q

what is redox (reduction) potentials?

A

electrons in redox active molecules have an inherent energy which is measured in voltage. These molecules have electrons within them that exist in different energy levels and this is the molecules reduction potential

37
Q

what is the relationship between low energy electrons and stability?

A

molecules with low energy electrons such as oxygen are more stable as they are more positive

38
Q

what is reduction potential?

A

the tendency of a molecule to accept or release electrons

39
Q

what does it mean if the reduction potential is more negative?

A

a more negative reduction potential means they are more likely to release electrons so the electron is in a higher energy orbital/state. Energy release form transferring electrons can be used to do work by being coupled to proton pumps

40
Q

what is the lowest energy electron acceptor in biological systems?

A

oxygen

41
Q

what is aerobic respiration?

A

respiration where oxygen is used as the terminal electron acceptor

42
Q

what is anaerobic respiration?

A

respiration where no oxygen is available so bacteria use an alternative electron acceptor

43
Q

what are oxidation reactions?

A

reactions that release electrons from the donor and protons are pumped by enzymes then electrons are passed to certain carrier molecules which then pass them onto other enzymes which can do further perform proton pumping actions and will ultimately give electrons to terminal electron acceptor proteins

44
Q

what does the ETC involve?

A

involves a series of membrane bound proteins and cofactors

45
Q

what does catalysation of the redox reactions in the ETC produce?

A

usually produces a proton motive force (PMF)

46
Q

what makes bacteria flexible?

A

their mitochondrial configuration

47
Q

what are the 4 key features of the electron transport chain (ETC)?

A

membrane
oxidative protein complexes
cofactors
reductive protein complexes

48
Q

what is a membrane?

A

a physical barrier that is needed to create a concentration gradient

49
Q

what are oxidative protein complexes?

A

complexes that liberate electrons from reducing powers and may pump H+

50
Q

what is the function of cofactors?

A

to transfer electrons between enzymes

51
Q

what is the function of reductive protein complexes?

A

to finally transfer electrons to a terminal electron acceptor and may pump H+

52
Q

what is complex I?

A

NADH dehydrogenase (large multisubunit enzyme) that oxidises NADH and reduced coenzyme Q (ubiquinone) by inducing structural changes that pump protons

53
Q

what is reduced coenzyme Q?

A

ubiquinone

54
Q

what is complex II?

A

succinate dehydrogenase which is the same enzyme from the CAC that generally does not pump protons

55
Q

what occurs at complex II?

A
  • FAD is a covalently bound intermediate here
  • succinate is oxidised
  • quinone is directly reduced
56
Q

what is quinone?

A

a small lipophilic chemical with an aromatic head group that accepts electrons with many different types with redox potentials

57
Q

what is a quinol?

A

a reduced quinone that is a small molecule that can freely diffuse through the membrane to the terminal enzyme

58
Q

what is cytochrome c?

A

a small protein that contains a heme group that accepts electrons that is generally only associated with oxidase enzymes that perform oxygen reduction

59
Q

what is cytochrome P4SO?

A

a heme containing enzyme that performs reactions

60
Q

what is complex III?

A

cytochrome bci transfers between quinol and cytochrome c by indirectly transferring protons using electron carrier acid/base chemistry. They are linked to complex IV and in many bacteria they are a super complex

61
Q

what is the function of complex IV?

A

takes electrons from cytochrome c and is used to terminally reduce oxygen by cytochrome c oxidase. Protons are taken up during catalytic intermediates and pumped

MICR221 Lectures 1-38 (10 decks)

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