C2.1

Question 1

how are chemical signals terminated

Answer 1

diffusion (away)

degregation (acetylcholinerase of ach in synaptic cleft)

reuptate (ssris)

inactivation of receptor (beta adrenergic receptors are inactivated fro epinephrine and get phospholyerised to prevent further binding.

feedback inhibitoin (insulin secreted to terminate glucose release to blood)

Question 2

steps common to all signal transfuction pathways

Answer 2

1. receptor activation
2. signal ampliication (w 2nd messenger)
3. signal activation
4. activatio of protein kinases
5. change in gene expression/cellular function

Question 3

signal transfuction is the

Answer 3

process that links the binding of signalling molecues to the eventual repsonse by a cell

Question 4

whay is the bohr shift and how is it caused

Answer 4

it is when co2 levels reduce haemoglibin affinity for o2 which shifts the o2 dissocociation curve to the right

Question 5

6 steps of bohr shift

Answer 5

1. co2 in blood plasma increaaes
2. co3 + h2o = h2CO3 (carbonic acid)
3. H+ ions dissociate in blood plasma
4. ph in blood decreases
5. change in 3 and 4º sturcture of haemoglobin
6. lower affinity of haemoglobin

Question 6

affinity meaning

Answer 6

the tendency for 2 substrates to bind together

Question 7

what is diff about foetal haemoglobin

Answer 7

it needs to have a hgher affinity for o2 (to get across placenta)

has 2 a and 2 gamma polypeptides

binds to more o2

Question 8

cooperative binding

Answer 8

the binding of each o2 molecule changes the shape of the haemoglibin so its affinity increases

Question 9

how many o2 can bind to haemoglibin and its pp

Answer 9

4 o2s can bind and it contains 4 pp, 2 alpha and 2 beta and each has a haem groupn

Question 10

Enviro factors impacting transpiration rate?

Answer 10

1, temperature: higher= faster transpiration cause more evalopration

2. humidity : higher humididy= more water putside so decrwase diffusion
3. wind speed (higher speed=more trnaspitation cause molecules diffuse away quicker, more space)
4. light intensity (stomata open more when light is higher

Question 11

transpiration happens througb the

Answer 11

stomata and this is gaseous exchange

Question 12

PP02 is the

Answer 12

partial pressure of oxygen

it is high in lung capillaries, causes high o2 affinity for haemoglobin, causing maximum binding

low in respiring tissues