Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

LSCI 230 > 4. Metabolic diversity > Flashcards

4. Metabolic diversity Flashcards

1
Q

Compare aerobes vs. Anaerobes vs. Facultative aerobes

A

– Aerobes: require oxygen for growth (Legionella)
– Anaerobe: oxygen is not required for growth (Clostridium)
– Facultative aerobe: oxygen is not required but enhances growth rate (E. coli)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the source of energy, electrons and carbon?

A

– Energy: chemicals or light.
– Electrons: organic compounds (glucose) or inorganic compounds (H2S).
– Carbon: organic compounds (glucose) or inorganic compounds (CO2).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Chemotrophy vs. Phototrophy

A
  • Chemotrophy: uses chemicals as energy

- Phototrophy: uses light as energy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Heterotrophs (Chemoorganotrophs) vs. Autotroph

Chemoorganotroph vs. chemolithotroph

A
  • Heterotroph: uses organic chemicals as carbon source
  • Autotroph: uses inorganic carbon sources (CO2)
  • Chemoorganotroph:: organic energy source
  • Chemolithotroph: inorganic energy source
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q 
Chemoorganotroph
Chemolithoautotroph
Chemolithoautotroph
Photoheterotroph
Photoautotroph
A

1) Chemoorganotroph:
- organic energy source
- organic electron donor
- organic carbon source
e. g. Protozoa, fungi,snimal cells

2) Chemolithoautotroph:
- Inorganic energy source
- Inorganic electron donor
- organic carbon source

3) Chemolithoautotroph:
- inorganic energy source
- inorganic e- donor
- CO2 carbon source
e. g. Nutrifying bacteria, sulfur bacteria

4) Photoheterotroph:
- Light energy source
- organic/ inorganic e- donor
- organic carbon source
e. g. purple nonsulfur bacteria

5) Photoautotroph:
- Light energy source
- inorganic e- donor
- CO2 carbon source
e. g.Algae, purple sulfur bacteria, green sulfur bacteria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

electron receptor of aerobic vs. anaerobic respiration.

A
  • Aerobic respiration uses oxygen as terminal electron acceptors
  • Anaerobic respiration/ Fermentation use other terminal e- acceptors
    e. g. no oxygen for final e acceptor in GI tract
  • *all the other electron receptor are higher in the redox tower compared to oxygen, so metabolism is less favourable than oxygen
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Denitrifying bacteria

  • what is the terminal e- acceptor?
  • Dentrification?
A
  • Dentrifying bacteria terminal e- acceptor is Nitrogen compounds
  • Dentrification: NO, N2O,N2 are gases lost from the environment
    e. g. sewage treatment to remove nitrate to prevent algal growth
  • -> loss of nitrate to atmosphere is harmful for agriculture, because plants use nitrate as a source of nitrogen.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Nitrate- based anaerobic respiration

A

reduce nitrate completely to dinitrogen, thus it can generate more energy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Sulfate & Sulfur reduction

compare the e- donor and terminal e- acceptor for

  • Desulfovibrio
  • Desulfuromonas
A
  • Desulfovibrio can use sulfate (SO42-) or sulfite (SO32-) as a terminal electron acceptor.
  • Desulfovibrio can use an organic compound (lactate) or an inorganic compound (H2) as an electron donor. When lactate is used additional ATP is produce.
  • Desulfuromonas use sulfur (S0) as a terminal electron acceptor
  • Desulfuromonas use acetate, ethanol and other organic compounds as electron donors.
  • H2S = rofen egg smell, can turn mud flats black due to the formation of metal sulfides.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

e- donor vs. terminal e- receptor

which one is higher in the redox tower?

A

electron donor is higher in the redox tower than final electron receptor
- more willing to donate e-, higher reducing power

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Phototroph:
Photoautotroph
Photoheterotroph

anoxygenic
oxygenic

A

Photoautotroph: CO2 carbon source

Photoheterotroph: organic carbon source

anoxygenic: purple& green bacteria
reducing power: sulfate& sulfur reducers

oxygenic: cyanobacteria, algae, green plants.
reducing power: oxygen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Absorption of light energy

  • light sensitive pigments
  • chlorophyll a
A
  • Light energy is used to generate a pmf.
  • depends on pigment used in the bacteria ,
    different light wave can be absorbed
  • chlorophyll a is stained purple, found in purple bacteria
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Why purple bacterias can live beneath green bacteria? some chemohetertroph and chemoautotroph can live in sediments?

Pigments diversity

A
  • light comes from the top
  • green bacteria absorbs red blue light
  • purple bacteria absorb the light that green bacteria do not absorb
  • so they do NOT interfere the growth each other
  • chemoheterotrophs and chemoautotroph use sulphur source or nitrogen source of energy
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Reaction center

A

pigments that surround the reaction center act as antennae to harvest light (LH) and funnel the energy to the RC.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Carotenoids and Phycobilins

A
  • Carotenoids are hydrophobic, light – sensitive pigments firmly embedded in the photosynthetic membrane
  • Carotenoids protects the system against bright light–(production of toxic forms of oxygen.)
  • Phycobilins form the main light- harvesting systems in Cyanobacteria: phycobilisomes. They harvest light of other wavelengths than chlorophyll.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Sites of photosynthesis - Eukaryotes

A
  • Plants, algae: chloroplast. The chlorophylls are attached to the membrane of the thylakoid.
    • Proton motive force is generated across the thylakoid membrane. pumping H+ inside the membrane
    – Stroma: alkaline, negative.
    – Intrathylakoid space: acid, positive.
17
Q

Sites of photosynthesis - bacteria

A

photosynthetic pigments are integrated into internal membranes:

  1. In the cytoplasmic membrane itself: heliobacteria.
  2. In intracytoplasmic membrane systems: purple bacteria (vesicles, lamellae)
  3. In thylakoid membrane: cyanobacteria, prochlorophytes
18
Q

Sites of photosynthesis - bacteria

Chlorosome

A
  • Chlorosome: present in green sulfur bacteria (Chlorobium) and green nonsulfur bacteria (Chloroflexus).
  • the best photosystem to capture energy at very low light intensity.
  • Green bacteria can colonize niches of very low light intensity,
    e. g.deep, anoxic aquatic habitat.
19
Q
  • Cyclic photophosphorylation
  • Noncyclic photophosphorylation
  • Reducing power
A

Cyclic photophosphorylation:
= no need for electron donor
- electrons go down ETC and then go back to RC, RC accept the electron and gets energized again
- Produce pmf for ATP synthase

Noncyclic photophosphorylation=a pair of electrons is used to produce PMF and NADPH.

Reducing power = need electron donor
- electrons are used to reduce NAD+ to NADH by ferredoxin.

20
Q

Anoxygenic Photosynthesis: purple bacteria

A
  • electron source:
    1) Purple sulfur: H2S;
    2) Purple nonsulfur: succinate (organic compounds, photoheterotrophs, also used as a carbon source)
  • In purple bacteria, NADH is produced by reverse electron flow: because energy of P870* is not enough to reduce NAD+.
  • use energy to create high pmf, strong enough to force electron back up the chain into NADH dehydrogenase to produce NADH
  • pmf supply energy (less ATP will be produced).

– Electrons are transferred to COMPLEX I of the respiratory chain (NADH dehydrogenase) which reduces NAD+ to NADH. (Involves reversal of its normal function)

21
Q

Anoxygenic photosynthesis

  • Green sulfur bacteria
  • Cyanobacteria
A

1) Green sulfur bacteria
- electron source: Oxidation of reduced sulfur compounds (H2S, S, S2O32-).
- Two systems run in parallel:
1. PMF–>ATP (electrons cycle)
2. Reduce NAD+, oxidize H2S

2) Cyanobacteria
- electron source: oxidized H2S. because H2S inhibits PSII, blocking the production of NADH
e- from H2S–>electron chain H2S–>NADPH
- Cyclic photophosphorylation:
e- (from P700) –> electron chain, creating pmf that drives ATP synthase.

22
Q

Oxygenic photosynthesis

A
  • PSII P680 Noncyclic photophosphorylation: a pair of electrons is used to produce PMF and NADPH.
  • PSI P700 Cyclic photophosphorylation: when reducing power is sufficient, e- return to cytochrome bf and goes to P700, no need for an electron source.
23
Q

pmf in oxygenic photosynthesis

A
  • accumulation of H+ inside the thylakoid lumen, making inside acid and positive
  • the chloroplast storm is relativelyy alkaline negative compares to thylakoid lumen.
24
Q

Chemoautotroph
e.g. Nitrifying bacteria
e.g. sulfur bacteria
( NOT sulfur reducer)

A
  • Use inorganic compounds as source of energy and electrons, and CO2 as carbon source.
25
Q

Nitrifying bacteria

A
  • use inorganic nitrogen compounds as electron donors: ammonia (NH3) and nitrite (NO2-).
26
Q

nitrification

A
  • complete oxidation of ammonia to nitrate
  • only occurs in aerobic conditions – requires O2.
    step 1. Nitrosomonas oxidizes ammonia to nitrite and another group
    step 2. Nitrobacter oxidizes nitrite to nitrate (NO3-).
    NH3 –>NO2- –> NO3-
  • nitrite is toxic, nitrate is a better source for plants
27
Q

Nitrosomonas

NH3–> NO2-

A
  • Final electron acceptor: O2.
  • AMO (ammonia monooxygenase) needs 2 e- to oxidize ammonia. Supplied by the Q.
  • For every 4 e- generated from oxidation of NH3 to NO2-, only 2 reach the Cyt aa3, the proton pump. other 2 goes to reverse e- flow to produce NADH.
  • NADH is produced by reverse electron flow. Q–> Complex I of the respiratory chain, pmf is the energy source.
    (strong pmf to force electrons back to AMO)
  • very low yield
28
Q

Nitrobacter

NO2- –> NO3-

A
  • Final electron acceptor: O2.
  • NXR: nitrite oxidoreductase.
  • NADH is produced by reverse electron flow. Q–>Complex I, pmf is the energy source.
  • Very low yield!
29
Q

Sulfur bacteria – Thiobacillus

A

• Oxidize sulfur compounds (source of
e-: H2S, S0, S2O32-).
• electron acceptor: O2
• Produce (SO4)2- and protons (sulfuric acid). causes acidic run-off from coal mines.(environmental pollution)
• NADH is produced by reverse electron flow.
• Sulfide (H2S) oxidation occurs in steps, the first step yielding S0, which is stored in cell inclusions.

30
Q

chemolithoautotroph:

methanogens vs. methanotroph

A
  1. Methanogens
    - strict anaerobes
    - produce CH4
    - Found in marshes, anaerobic sediments, landfill sites, intesWnal tract of animals.
  2. Methanotrophs
    - aerobes, require oxygen to produce NADH
    - use CH4 as a source of carbon and energy (electron donor).
    - Present in aerobic zones overlying anaerobic sediments.
31
Q

Fixation of CO2 – Calvin cycle

A
  • Photoautotrophs: algae, cyanobacteria, purple sulfur and green sulfur bacteria.
  • Chemoautotrophs: nitrifying bacteria, sulfur bacteria, some methanogens.
  • Eukaryotes: enzymes in the stroma of chloroplast.
  • Prokaryotes: enzymes in the cytoplasm.
32
Q

Calvin cycle

A
  • 6 CO2 + 12 NADPH + 18 ATP——> C6H12O6 + 12 NADP+ + 18 ADP + 17 Pi

LSCI 230 (9 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions