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Micro > Chapter 14: Metabolic Diversity of Microorganisms > Flashcards

Chapter 14: Metabolic Diversity of Microorganisms Flashcards

1
Q

Light reaction

A

produces ATP and NADPH
- requires an electron donor from environment (water, H2S, H2)

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2
Q

Dark reactions

A

reduce CO2 to cell material for growth
requires ATP and e- (NADH/NADPH)

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3
Q

oxygenic photosynthesis

A

oxidation of H2O produces O2
-cyanobacteria

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4
Q

anoxygenic photosynthesis

A

oxidation of H2S produces SO42-
-purple/green sulfur bacteria

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5
Q

chlorophyll and bacteriochlorophyll

A

tetrapyrroles w magnesium
- different pigments allows different phototrophs to absorb different wavelengths

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6
Q

photocomplexes

A

proteins housed within membranes
- reaction centers contain pigments
- antennae pigments surround and funnel light energy to rxn centers

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7
Q

chloroplasts

A

in eukaryotes
- intercellular organelles containing thylakoids

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8
Q

thylakoids

A

sheet-like membrane systems

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9
Q

chlorosomes

A

capture low light intensities
- in anoxygenic green sulfur bacteria, filamentous anoxygenic phototrophs, & phototrophic Acidobacteria

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10
Q

Carotenoids

A

widespread accessory pigment
hydrophobic
yellow, red, orange, brown, or green
absorb blue light
-quenches toxic oxygen species, prevents dangerous photooxidation

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11
Q

phycobiliproteins

A

the main light-harvesting systems of cyanobacteria and red algae chloroplasts
- red/blue-green tetrapyrroles: “bilins” bound to proteins
pro: integrated into cytoplasmic membrane
purple bacteria: chromatophores/lamellae
cyanobacteria: thylakoids

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12
Q

phycoerythrin

A

absorbs ~550nm (red)

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13
Q

phycocyanin

A

absorbs ~620 nm (blue)

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14
Q

noncyclic photophosphorylation

A

e- do not circle back and reduce NADP+ to NADPH

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15
Q

cyclic photophosphorylation

A

occur if cell requires less NADPH to produce more ATP

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16
Q

autotrophy

A

CO2 is reduced and assimilated into cells
- in phototrophs: often called “dark rxn”

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17
Q

Calvin Cycle

A

Requires:
6 CO2
CO2 acceptor
12 NADPH
18 ATP
RuBisCO
phosphoribulokinase

To make 1 Glucose

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18
Q

carboxysomes

A

inclusions containing and improving efficiency of RubisCO in many autotrophs
- increase CO2 concentration (instead of O2)
-250 RubisCO/carboxysome

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19
Q

Reverse Citric Acid Cycle

A

aka reductive TCA cycle
used by green sulfur bacteria (and some chemoautotrophs)
more efficient:
4 NADH
2 reduced ferredoxins
10 ATP

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20
Q

Hydroxypropionate Cycle

A

2 CO2
6 H
3 ATP
into glycoxylate

21
Q

Nitrogen fixation

A

atmospheric gaseous N2 -> ammonia NH3
- no eukaryotes fix nitrogen
16 ATP

22
Q

nitrogenase

A

enzyme complex composed of dinitrogenase and dinitrogenase reductase
-inhibited by oxygen

23
Q

Ways of protecting nitrogenase from oxygen

A

oxygen-retarding slime layer
removal by respiration
anoxic heterocyst formation

24
Q

Assaying nitrogenase

A

acetylene reduction
-nitrogenases reduce other triply bonded compounds, including acetylene, to form ethylene

25
Q

assimilative reduction

A

consumes energy
ie. NO3-, SO4-, and CO2 reduction for new sources of N, S and C for new cell material

26
Q

dissimilative reduction

A

conserves energy
product of reduction is a small molecule that is excreted (N2, H2S, CH4)
- only in anaerobic respiration

27
Q

H2 oxidation

A

H2 + 1/2 O2 -> H2O
very exergonic, can be coupled to ATP synthesis
catalyzed by hydrogenase

28
Q

H2 bacteria

A

most are chemoorganotrophs
CO2 fixed by Calvin Cycle

29
Q

Oxidation of Sulfur compounds

A

H2S, S0, S2O3- (SO3 2- common)
in stages, first produces S0 (deposited in cell as an energy reserve)
produces H+ (acidifies environment)
Sox system

29
Q

facultative chemolithotrophs

A

repress synthesis of Calvin cycle and hydrogenase enzymes when organics present catalyzed by hydrogenase

29
Q

Sox System

A

oxidizes reduced sulfur compounds directly to sulfate
4 key proteins: SoxXA, SoxYZ, SoxB, SoxCD

30
Q

sulfur-oxidizing microbes that store sulfur granules lack _______

A

SoxCD (sulfur dehydrogenase)

31
Q

chemoautotrophs

A

aerobes oxidizing ferrous iron at low pH
Fe2+ -> Fe3+

32
Q

ferrous hydroxide

A

Fe3+ + 3 H2O = Fe(OH)3 + 3 H+
insoluble, precipitates in water, driving down pH

33
Q

Bioleaching

A
34
Q

Assimilative sulfur metabolism

A

incorporation of sulfate for biosynthetic purposes to make cysteine, methionine, and other organosulfur compound

35
Q

Dissimilative sulfur metabolism

A

use of sulfate as an electron acceptor for energy conservation and production of large amount of H2S (excreted)

36
Q

Sulfur reduction

A

1 ATP/SO4- reduced to HS-
e- transport reactions lead to PMF formation

37
Q

methanogenesis

A

biological production of methane
catalyzed by strictly anaerobic Archaea (methanogens)
- form of anaerobic respiration
reduction of CO2by H2 to form CH4
NEEDS TRUE ANOXIC CONDITIONS

38
Q

methanogens

A

present in freshwater sediments, sewage sludge digesters, bioreactors, animal intestines

39
Q

C1 carriers

A

coenzyme in methanogenesis
- carry C1 units along path of enzymatic reduction (methane, methanol, etc.)

40
Q

methanogenesis coenzymes

A

Coenzyme M (last step)
Coenzyme F430 (last step-not a carrier)
Coenzyme F420 (Flavin derivative, fluoresces @420 blue-green)
Coenzyme B (terminal step, catalyzed by methyl reductase enzyme complex)

41
Q

methylotrophs

A

oxidize methane (+ other C1 organic compounds) as electron donors

42
Q

aerobic methane oxidation

A

CH4 -> CH3OH -> CH2O -> HCOO- -> CO2

43
Q

serine pathway

A

acetyl-CoA synthesized from CH2O and CO2
needs 2 NADH and 2 ATP

44
Q

ribose monophosphate pathway

A

all carbon derived from CH2O (no NADH)
1 ATP per glyceraldehyde -3-phosphate(G-3-P) synthesized
reversal of glycolysis produces glucose

45
Q

anaerobic oxidation of methane (AOM)

A

can occur by an association (consortium) of 2 organisms: sulfate-reducing bacterium (SRB) and Archaea

46
Q

RuBisCO

A

active in carboxysome
very low affinity for CO2 compared to O2

47
Q
A

Micro (9 decks)

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