Part 2 Flashcards
(22 cards)
How can fever during infection help the immune system response?
It increase the proliferation and movement of white blood cells
and enhances the rate of phagocytosis.
How can high temperature cause stress and problems?
Above the optimum the cell loses control of the plasma membrane as it becomes fluid and diffusion becomes harder to control.
Proteins no longer fold properly and thus can’t function properly
How do membranes respond to heat?
The lipid composition of the membrane changes
There is more saturated fatty acid.
The double bond in the saturated fatty acid bends the tail making it more viscous.
There is also more cholesterol which is more stable.
This packs the membrane more tightly so it is less fluid - maintaining fluidity.
What are heat shock proteins?
Heat shock proteins are a group of proteins that are produced when a cell is exposed to elevated, sub-lethal temperatures.
What do heat shock proteins do?
They protect the cell if it is exposed to what would have been a lethal temperature rise.
They also help fold proteins properly, stabilising them as they come of the ribosome so that they can function properly (chaperonin)
When are heat shock proteins produced?
During sub-lethal temperature rises or in response to other stresses such as oxygen or nutrient deprivation
What do heat shock proteins show about cells?
They show redundancy - its a crucial system to keep forming proteins
Geogemma barossii
is a prokaryote from the archaea domain that grows in sulphur and iron rich hydrothermal vents at 121C
Adaptions of Geogemma barossii
High G-C levels in their third codon position
-supercoiling of DNA so more stable
-temperature stable with strong bonds
-changes to membrane composition
ether bond in phospholipids rather than ester bonds
What problems can low temperatures cause?
Slow enzyme reaction
rigid and viscous membranes
Ice crystals
What are glycoproteins?
Glycoproteins are proteins with a sugar attached.
What is glycosylation?
The process of attaching a sugar. (post-translational modification).
What happens to proteins in cold temperatures?
Glycoproteins become more abundant in cold temperatures
Many are present in the plasma membrane with the carbohydrate region presented outside the cell
to protect the cell.
What does the addition of a sugar molecule to the protein do?
glycosylation of the protein stabilises the protein structure in the extracellular environment therefore offering some protection from the environment.
It provides a hard shell
and helps protect against ice crystal formation.
What else is present in the plasma membrane and has the same job as glycoproteins in cold temperautres?
Glycolipids
How does the Artic fish survive temperatures lower than -2c
Use glycoproteins to stop them from freezing.
They have a large amount of glycoproteins.
Ice crystals form along the length of the glycoproteins and so they wont cause damage to the cell
How does the Rana sylvatica survive low temperatures of -16C?
Wood frog
can survive multiple freezing and thawing cycles through the use of anitfreeze glycoproteins and high glucose levels.
How do high glucose levels stop the Rana sylvatica from freezing?
Changes the osmotic balance in the blood so fewer ice crystals form
Planococcus halocryphilus survives what temperatures?
Can grow at -15C and stay metabolically active at -25C
Psychophiles can do what? and why?
Survive at vry low temperautres because they have proteins and metabolism optimised for these temperatures.
What are the proteins like in psychophiles
The proteins are structurally more flexible. they are more open and so higher temperatures would destory them
Adaptations allow psychophiles to survive at low temperatures but what does this mean for metabolic rate?
Metabolism will be slower along with other rates
diffusion
growth
