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APS 325: Life in Extremes > Lecture 4: extremes of temperature > Flashcards

Lecture 4: extremes of temperature Flashcards

1
Q

the majority of organisms an temperature ranges

A

majority can only tolerate a narrow range of temperatures

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2
Q

cryophiles (psychrophiles)

A

low temperature optima for growth

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3
Q

what do we find at -18 DC

A

himalayan midge active at -18 DC and some single celled organisms

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4
Q

mesophiles

A

mid-range temperature optima (humans)

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5
Q

thermophiles

A

high temperature optima

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6
Q

extremeophiles grow best at a __ range of extreme conditions

A

narrow

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7
Q

temperature of most of the oceans

A

are at approx 5DC and ocean depths are at 1-2 C

–> COLD

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8
Q

cold areas on earth

A
  • oceans

- poles (rarely exceed 0DC)

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9
Q

ice is rarely completely ____

A

frozen

  • inclusions of liquid water are common
  • channels of brine pockets present
  • condensed microscopic halophilic environments
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10
Q

lots of organisms can survive cold organisms but can they ___

A

GROW

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11
Q

Fragilaria sublinearis

A
  • diatom
  • eukaryotic algae
  • grows on underside of ice flow (stable) and photosynthesises on the light filtering through
  • stick together
  • gives ice flow a brown colour
  • temp optimum = 7-12 DC
  • but will grow at 1-2DC
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12
Q

Fragilaria sublinearis adaptations for survival

A
  • stick together
  • high light harvesting capacity (limited light through ice)
  • lipid structure which allow them to function at low temp (polyunsaturated fatty acids)
  • cryoprotectants (prevents freezing)
  • osmoprotectants
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13
Q

Melosira arctica

A
  • filamentous diatom
  • which can form large growths on the underside of ice floes
  • low CO2, low light environments, small temp range
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14
Q

2 filamentous diatoms (eukaryotic algae) found under ice sheets

A
  • Melosira arctica

- Fragilaria sublinearis

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15
Q

massive ___ have been found under sea ice

A

algal blooms

– due to new tech (access is difficult drill through 1/2m of ice) ?? or due to Climate change???

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16
Q

studying diatoms: ____ approaches allow us to study their adaptions

A
  • genomic approaches allow us to study their adaptions
  • culture it in lab
  • unusual no. of light harvesting complex genes
17
Q

‘Red snow’

A
  • eukaryotic algae
  • Chlamydomonas nivalis
  • photosynthetic
  • common in snow fields
  • summer you get melt water pools, but in winter u get red snow
  • survive when frozen, thrive in pools??? –> assumption
  • extreme temp = resistant spores with photo protective red pigment == RED
18
Q

Chlamydomonas nivalis =

– global spread?

A

north america, New zealand, australia, europe –> LOW CO2 environments

19
Q

red snow name

A

Chlamydomonas nivalis

20
Q

Chlamydomonas nivalis physiology

A
  • pink form = resting form? JUST surviving?
    • Williams et al 2003 used gas exchange to measure photosynthesis in dense algae blooms
  • GAS EXCHANGE OCCURS IN RED SNOW
21
Q

problems organisms face at low temperatures

A
  • lipid membranes become semi-crystalline and lose integrity at low temperatures (e- transport point, structure)
  • enzyme activity becomes v slow
  • ice crystal formation can disrupt cell structure
22
Q

organisms which exist at low temperatures produce membranes which are rich in __ fatty acids

A

unsaturated (double bonds in chain)

23
Q

membranes at low and high temp

A
  • at low = semi crystalline become brittle
  • middle = gel
  • at high = blow up
24
Q

appearance of saturated and unsaturated fatty acids

A

unsaturated = kink. stops them packing together so well

- sat = tougher, stick together at high temp

25
Q

saturated / unsaturated fatty acids come crystalline at low temp first

A

saturated! as already ordered, better at higher temps

26
Q

enzymes in low temp organisms

A

adapted! to the environment

  • change in aa sequence
  • –> BUT MAKES IT OBLIGATE extremeophile, doesnt work well at other temps
27
Q

ice crystal formation damage to cells, how do organisms protect themselves

A
  • cells physically disrupted
  • psychrophilic organisms can produce CRYOPROTECTANTS
    e. g. glycerol
  • -> lower freezing point
  • -> cells containing glycerol freeze into a glass state (tiny crystals)
  • -> compatible solute
28
Q

adaptations organisms have to cold environments

A
  • lipid composition is rich in polyunsaturated fatty acids
  • enzymes adapted
  • cryoprotectants are produced
29
Q

fissures

A

small gaps in ice crystals, mini brine veins, solutes excluded so in liquid, high salt prevent freezing, BACTERIA also present
- Hypersaline

30
Q

bacteria in brine vein

A

too big to move between veins, but product from the bacteria (metabolic interactions) can move through veins

31
Q

is life possible in solid ice?

A
  • gases can diffuse through (N2, CO, CH4, CO2, O2)
  • so living bacteria in frozen ice
  • suspended animation? WE DONT KNOW
32
Q

lakes beneath ice sheets: what do they tell us=

A
  • Lake Vostok
  • cores provide valuable info about climate change
  • kept liquid by pressure
  • isolated from rest of environment for millennia
  • more lakes now discovered
33
Q

drilling into lakes beneath ice sheets:

A
  • for CC info
  • ceased before contamination
  • ice cores from the melted/refrozen zone contains indication of life (micro-organisms can be cultured)
  • smapling w/o contamination is challenging
34
Q

conditions of lakes beneath ice sheets=

A
  • Dark (3.5km of ice above)
  • – no photosynthesis
  • – hot springs may exist within lake
  • cold
  • – -3 DC
  • high pressure
  • – 380 atmospheres
  • low nutrient
  • – thick sediment does exist
35
Q

risk of contamination to lakes beneath ice sheets

A

kerosene (to keep bore whole open) in drilling down into lake

36
Q

now new lakes under ice have been discovered what do we know

A

network between them, vostok not so independent and therefor preserved

37
Q

successful lake beneath ice sheet sampling: Lake Whillans

A

found microbial system,

  • knew contamination was to occur.
  • Measure contaminants and compare that to sample
  • connected to sea
  • not as deep
38
Q

conditions in Lake Vostok similar to those of Europa

A
  • Europa (a moon of jupiter)
  • may contain a liquid ocean under a frozen crust
  • eruptions of cry-volcanoes suggest that this ocean is rich in organic material

APS 325: Life in Extremes (15 decks)

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