Feb. 24th - Temperature Stress

Question 1

temp and membranes

Answer 1

• low = gel phase
• optimal = liquid crystalline phase
• high = membrane fluidization

Question 2

phase change

Answer 2

when there is an extreme temp. change it causes membrane phase change

Question 3

temp on proteins

Answer 3

• activity has an optimum (~40)
• flexibility increases w temp

Question 4

protein aggregates

Answer 4

misfolded hard to deal w proteins

Question 5

extreme changes in temp on membranes

Answer 5

phase changes

Question 6

mild temp changes on membranes

Answer 6

low=decreased fluidity
high=increased

Question 7

extreme temp changes on proteins

Answer 7

cold and heat denaturation

Question 8

mild temp changes on proteins

Answer 8

influences flexibility

Question 9

membrane processes affected by temp change

Answer 9

ALL transmembrane transport types

Question 10

protein processes affected by temp change

Answer 10

• some transmembrane transport
  -metabolism (enzymes) ex. ATP synthesis
  -cell signalling (ex. receptors)
  -cytoskeletal processes

Question 11

steps of cell signalling

Answer 11

1. reception .. of external stimuli
2. transduction .. relay molecules
3. response

Question 12

what can act as a signal

Answer 12

anything that can alter the structure of a receptor protein
ex. temp, pH, physical stimuli, signalling molecules (ligands)

Question 13

detecting temp. change via membrane fluidity changes

Answer 13

membrane fluidity changes change the shape and activity of receptor protein

Question 14

synechocystis sp

Answer 14

proks. Hik33 signal receptor activated by decreased temps … leads to ^^^ expression of genes important for tolerating decreased temps

Question 15

ways cells detect temp changes

Answer 15

1. membrane fluidity changes which causes receptor proteins to change in shape and activity
2. temp. directly changes the shape and activity of receptor proteins
   ex. neurons in animals

Question 16

TRP channels

Answer 16

transient receptor potential

• temperature gated
  -directly sense temp changes
  -some are stimulated by specific temps and chemicals (ex. human TRPM8 : 18-25 deg. + menthol)

Question 17

Heat sensing neurons in snakes

Answer 17

heat changes conformation of specific trp channels … ions enter/ leave via channel (transduction) … response = action potentials (electrical signalling)

Question 18

neurons

Answer 18

excitable cells

Question 19

localized changes in ion concentrations can

Answer 19

initiate action potentials (ex. electrical signals)