Lec 8

Question 1

“EXTREME” ENVIRONMENTS BASED ON: (5)

Answer 1

Temperature
Moisture
pH
Salinity
Contaminants

Question 2

(LOW TEMPERATURE ENVIRONMENTS)

Sulfide gradients result in

Answer 2

microbial sulfur cycling

Question 3

Cold adapted microbes synthesize

Answer 3

cold adapted enzymes which have higher activity at low temperatures

Question 4

PSYCHROPHILES optimal temperature for growth =

Answer 4

-15 –> +15*C

Question 5

(PSYCHROPHILES)

Membrane adaptations:

Answer 5

1. ) Increase in unsaturation
2. ) Decrease in average chain length
3. ) Increase in methyl branching (only seen in bacteria)

Question 6

(PSYCHROPHILES)

Proteins adaptations:

Answer 6

1. ) Increase lysine:arginine ratios & reduced arginine / proline content
2. ) Glycine clustering at catalytic site
3. ) Decreased inter-domain & subunit ion, electrostatic, and aromatic interactions
4. ) Increased hydrophobic surface residues / reduced core hydrophobic residues
5. ) Increased size & number of enzyme cavities
6. ) Increased mobility of catalytic site
7. ) Extended surface loops (Predominance of neutral AAs) (Reduced proline content)

Question 7

To battle ice, psychrophiles have

Answer 7

ice binding proteins (bind ice crystals and stop them from spreading)

Question 8

• Thermophiles grow optimally between =
• Hyperthermophiles =
• Most thermophiles isolated =

Answer 8

= 45-70C
= anything that can grow above 80C
= archaea

Question 9

(THERMOPHILES)

Membrane adaptations: (3)

Answer 9

1. ) Decrease in unsaturation
2. ) Increase in average chain length
3. ) Presence of monolayers (Only in Archaea)

Question 10

(THERMOPHILES)

Proteins adaptations: (6)

Answer 10

1. ) Proteins are rigid
2. ) More inter-subunit interactions
3. ) Less and shorter loops
4. ) More metal binding sites
5. ) More electrostatic interactions
6. ) Increased oligomerization

Question 11

Heat-Adapted Proteins: Stabilizing Interactions

Answer 11

1. ) Less cavities
2. ) More ion pairs
3. ) Less/shorter loops
4. ) More AT/proteins (histones) associated

Question 12

Microbes that live high pressure environment:

Answer 12

barophiles

Question 13

High pressure has the same effects on cellular membranes as

Answer 13

low temperature

Question 14

Barophiles’ proteins are

Answer 14

less flexible - so similar to high temperature organisms

Question 15

(Barophiles)

The pressure can cause…

Answer 15

…normally fluid membranes to become waxy and impermeable to nutrients