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EcologyA > Abiotic Effects > Flashcards

Abiotic Effects Flashcards

1
Q

Abiotic factors

A 
Temperature
Pressure
Salinity 
PH
Oxygen
Radiation
Heavy metals and toxic compounds
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2
Q

Abiotic boundaries for earth and other plants

A

Restraints on earths life is a combination of pressure, PH, temp and salinity
Life has been detected in all regions of the earth
If same criteria are placed on other planets suggests life is possible

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3
Q

Extremophile

A

Org that grows optimally under 1+ chemical/physical extreme condition

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4
Q

Evolution of earths extremophiles

A

Most of earths history only microbial life existed
Bacteria and archaea branches ~3.8bya
Prokaryotes more evolved to inhabit varied and extreme abiotic conditions
Present day O2 concs only in place the last few hundred million years

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5
Q

PH nomenclature

A 
hyperacidophile = PH 9
Hyperalkiphile = >PH 11
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6
Q

Temperature nomenclature

A

Psychrophile =<15C
Mesophile =20-45C
thermophilic =45-80C
Hyperthermophile = >80C

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7
Q

Salinity nomeclature

A

Non-halophile = <1.2%
Halotolerant = 1.2-2.9%
Halophile = >8.8%
Extreme halophile = >14.5%

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8
Q

Pressure nomeclature

A 
Piezotolerant = 0.1-10MPa
Piezophile = 10-50MPa
Hyperpiezophile = >50MPa
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9
Q

Water nomenclature

A

Xerophile = <0.7

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10
Q

Micro environments/niches

A

Abiotic gradients creating micro niches within microscopic distances

  • affected by microbial activities
  • what grows where determined by nutrient availability

E.g. in soil aggregate decreasing O2 towards the centre until anoxic = aerobic microorgs on outside and anaerobic in centre

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11
Q

low temperature environments

A 
Antarctic ice sheets 
Permafrost in tundra
Sea ice
Glaciers and frozen lakes
Deep ocean and sea floor
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12
Q

Describe psychrophily

A

Ice contains <100nm layers of liquid water
W/ high concentrations solutes
Large enough gaps to support microbial life
Microbial activity measured at -40C in tundra
E.g. sea ice bacterium psychromonas

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13
Q

adaptations to psychrophily

A
  1. Proteins/enzymes
    - Ahelix and b sheet structures = more flexibly
    - polar > hydrophilic AA content
  2. Cytoplasmic membranes
    - high content unsaturated and short chain fatty acids
    - polyunsaturated fatty acids e.g. unsaturated diether lipids (UDLs) in methanococcoides burtonii
  3. Cold shock proteins
    - RNA regulation: prevents inhibitory mRNA secondary structure formation
  4. Cyroprotectants
    - glycerol = prevents ice crystals
    - extracellular polysaccharide substances (EPS)
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14
Q

High temperature environments

A

Hydrothermal vents
Hot springs, geysers and fumaroles
Hot mud volcanoes

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15
Q

E.g. hyperthermophile bacteria

A

Thermotoga maritima

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16
Q

Hyperthermophile adaptations

A
  1. stabilising proteins
    - hydrophobic cores
    - disulphide bonds
    - stabilisation by chaperones (assist with protein folding )
  2. Stabilising DNA
    - reverse DNA gyrase = positive supercoils
    - DNA binding proteins or archeal histones
  3. Stabilising lipids
    - dibiphtynal tetraether lipids in archaea
    - bacterial diether lipids = produce membrane that are less permeable so better in extremes
17
Q

Is there an upper temp limit on life?

A

People used to think it was 60C
Now we think it is 130C
Have seen life at 122C

18
Q

Describe Geogemma barossi

A

Alive at 122C
Archaea in hydrothermal vent
Obligate anaerobe
Iron reducing chemolithotroph = needs iron for energy

19
Q

Describe thermus aquaticus

A

Bacterium from hot spring
Optimum temp = 65-70C
Chemotroph
Source of Taq polymerase = no PCR without these

20
Q

Piezophiles

A

Pressure increases by 1 mega pascal per kilometre in the oceans so often found underwater
They are often facultative anaerobes belonging to psychrophiles
Hyperthermophile-piezophiles are archaea

21
Q

Piezophile adaptations

A

High proportion of unsaturated fatty acids in membranes = prevents gelling at high pressure
Specific outer membrane protiens (OmpH) porins allow molecules to diffuse through membrane

22
Q

Hyper saline (High salt) environments

A

Seawater evaporating ponds
Salt lakes
Saline soils

23
Q

How to halophiles regulate osmolarity

A

Regulation of turgor pressure
Osmolytes = solutes that increase osmolarity within cell without affect metabolism e.g. glycerol
‘Salt in’ cytoplasm accumulation of K+ as osmolytes

24
Q

bacteriorhodopsin

A

Bacteriorhodopsin produced by halobarchaea
Allows growth in absence of water and dissolved O2 as saline environments sry out red/purple colouration as absorbs light at 570nm
1st membrane to have its 3D structure elucidated
7 membrane spanning a-helixes > each with ~25 hydrophobic AA with one molecule of retinol in centre of the protein
- all trans retinol molecules activated by light and protonated

25
Q

Energy transduction in bacterhodopsin

A

light mediated ATP synthesis

  1. Retinal protonated when exposed to light = converted from trans to cis form
  2. Retinal transfers its H+ to a protein. Protein has conformational change and carries H+ across cell membrane = released into periplasm
  3. Protons in periplasm re-enter cell via ATP synthase = ATP generated
  4. De protonated retinal picks up another H+ from cytoplasm
    Cycles back
26
Q

Low PH environments

A

Sulphur lakes
Acid drainage
Cave ‘snotties’ - bacteria hanging from ceiling

27
Q

How do acidophiles adapt to high PH sand e.g. of acidophile

A

E.g. = E.coli

Continuously, actively pump out H+

28
Q

How do alkaliphiles adapt to high PH sand e.g. of alkaliphiles

A

E.g. Bacillus firmus

Reduce internal PH
Call walls contain acidic polymers
Na+/H+ antiporters systems and ATPase driven expulsion

29
Q

Types of anaerobic metabolism

A

Fermentation

Anaerobic respiration

30
Q

Fermentation

A

Same organic compound as e- donor and e- acceptor

ATP formed by substrate level phosphorylation

31
Q

Anaerobic respiration

A

Formation of proton motif force (PMF) by oxidative phosphorylation
Involves electron acceptor other than O2

32
Q

Niche partitioning in marine sediment

A

As further down becomes more anaerobic and alternative electron acceptor to O2 changes
3 zones:
Oxic = aerobic respiration, fermentation, nitrate reduction
Suboxic = manganese or iron reduction
Anoxic = sulphate reduction or methanogenesis (using carbon dioxide)

EcologyA (18 decks)

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