lecture 2

Question 1

THERMOPHOLE

Answer 1

Thermophiles: Adapted to high temperatures e.g. thermal vents and hot springs. EXAMPLE: Obsidian
pool in Yellowstone national park which is ~150-350C

Question 2

phsychrophile

Answer 2

Adapted to low temperatures e.g. arctic and Antarctic. Half of the Earth’s surface is
oceans between 1-4ᵒC. Temperatures in Antarctic are more stable than artic (-10 to -30)

Question 3

Protein structure regulation

Answer 3

Stable proteins for thermophiles but psychrophiles have efficient proteins

Question 4

Adaptations of hyperthermophiles 1

HYDROPHOBICITY

Answer 4

• heat stable proteins have more hydrophobic interiors
  -prevents unfolding or denaturing
• Thermophilic proteins are kept stable, so more energy is needed to cause protein conformation
• Avoid Cys and Thr residues and prefer Arg and Tyr
  o They do NOT favour proline and where there are breaks between a and B helices
  o Prefer carbon and sulfur bonds as hydrogen bonds are more unstable
  o Prefer more a helices (but both are needed in proteins)

Question 5

adaption of hyperthermophiles

ABUNDANT CHAPERONE PROTEINS

Answer 5

• MAINTAIN FOLDING

- 10% OF GENES IN GENOMES ARE CHAPERONES

Question 6

A O H,

MONOLAYER MEMBERANES OF DIBPHYTANYL TETRAETHERS

Answer 6

• SATURATED acids that make them RIGID
• prevents membrane DEGRADATION
• increased cyclisation, so packaged TIGHT and LESS LIPID MOVEMENT
• 10-20X THICKER than normal
• some species have INCREASED MOTION which increasesPROTON PERMEABILITY (IMPORTANT TO ENZYMEATIC ABILIUTY)

Question 7

dna preserving substrates

Answer 7

Reduces mutations and damage
o E.g. DNA gyrase and Sac7d
o Large mutation rate to maintain integrity
o Lots of positive changes but needs lots of active repair mechanisms e.g. DNA pol helices

Question 8

Surviving on sulphur, hydrogen and other materials that other organisms can’t metabolise

Answer 8

• live without sunlight or organic carbon source
• save metabolic activity through using sodium/proton transport exchange
• converts PMF (proton motive force) into SMF (sodium motive force)
  o High PMF generated by high respiration rate
  o Saved energy used for other processes e.g. secondary transport
  o Lots of TM proteins
  o H+ and sodium used to produce ATP
  o EXAMPLE: Thermophilic cyanobacteria in geysers

Question 9

extremosymes

Answer 9

enzyme from extremophile

Question 10

EXAMPLE: P. abyssi and T. aquaticus

Answer 10

• Hydrothermal vents: high temperatures, low nutrient levels (mostly only oligotrophs, survive at low nutrient level) and high pressures (increase rate of 1atm for every 10 meters in depth in deep sea)
• Increased pressure = decreased enzyme-substrate binding

Question 11

EXAMPLE: Thermus thermophilus

Answer 11

o Small circular genome (2Mbp), 2000 predicted genes
o Large plasmid >200 kbp
o shows features of a scavenger (lots of peptidases involved in protein folding or stability)
o Lots of overlap between genomes T. thermophilus and D. radiodurans (horizontal gene transfer?)
o Lots of NTN codons (nucleotide – thymine – nucleotide), T instead of U
o NTN encodes exclusively non-polar hydrophobic amino acids (for stabilisation)
o Mutated rapidly to preference specific codon = atypical residues = stability
o Traps and protects H bonds from moving

Question 12

Barotolerent

Answer 12

: microbes live at 1000-4000 meters

Question 13

Barophilic

Answer 13

microbes live at >4000 meters

Question 14

1) Bacteriophages

Answer 14

o Cannot culture in lab very well as need lots of components
o Electron dense structures
o Lack some metabolic processes, shows did not evolve alone and live in communities

Question 15

3) Archaeal viruses

Answer 15

o Large circular double-stranded DNA genome ~20,000 bp (not common to bacterial viruses)
o No similarity to any other known genome
o Capsid proteins found similar with bacteria and viruses