AP7 Flashcards
What is the definition of tolerance?
The capacity of an individual has to endure continued subjection to environmental conditions without adverse reactions
What is a zone of tolerance?
Zone bounded by upper and lower zone of physiological stress within which the organism can survive for an indefinable period
What are 2 things which affect tolerance?
1) Thermal history
2) Seasonal changes in temp
3 primary functions of heat shock proteins?
1) Promote proper folding or refolding of proteins
2) Prevent potentially damaging interactions with proteins
3) Aid in the disassembly or formations of protein aggregates (where misfolded proteins aggregate)
3 jobs of molecular chaperones
1) Stabalise ? proteins
2) Minimise probability of inappropriate interactions
3) Involved in successful folding, assembelly, regulation and degredation of ? proteins
Describe the job of heat shock proteins when a protein is denatured
1) Denatured proteins are detected
2) Heat shock proteins are produced
3) They refold the denatured proteins
How do heat shock proteins avoid the stress which is denaturing the other proteins?
1) Better hydrogen bonds
2) Hold their specific shape despite stress
3) Better secondary structure
What is heat shock proteins secondary function?
Immune function
- If found extracellularly it suggests that cell membranes have been damaged
- Serves as ? signal to body
- Presents antigens from diseased cells to T cells
Why are heat shock proteins not expressed all the time?
They are costly
Experiment showed increased mortality and slower development
2 negative consequences of ice formation caused by sub-zero temperatures?
1) Cells shrink
2) Cell membrane is damaged
What are 2 ways to deal with sub-zero temperatures?
1) Freeze avoidance- keeps bodily fluids liquid
2) Freeze tolerance- control where, when and to what extent ice forms, produce antifreeze proteins, inhibit ice growth
3 examples of freeze avoidance?
1) Dry hibernation site
2) Physical barrier such as wax cuticle
3) Decrease the temp at which bodily fluids freeze by supercooling or cryoprotection synthesis
Supercooling= removal of nucleation source so ice cant crystalise eg. food/dust particles
Cryoprotectant= increase of solute concentration
How do ice-nucleating proteins work?
- Lower an insects body temp
- Initiate ice formation at relatively warm temperatures
- Allows insect to moderate the rate of ice growth
- Adjust more slowly to the mechanical and osmotic pressures from ice formation
