transport of gases in blood

Question 1

what is the structure of haemoglobin ?

Answer 1

• four polypeptide chains, each bound to one haem group
• each haem group can combine with one oxygen molecule
• can combine with a maximum of 4 oxygen molecules - oxyhaemoglobin

Question 2

what type of structure does haemoglobin have ?

Answer 2

quaternary structure

Question 3

what is the Bohr effect ?

Answer 3

• when a high CO2 conc causes the oxyhaemoglobin curve to shift to the right
• the affinity for oxygen decreases bc the acidic C02 changes the shape of haemoglobin slightly

Question 4

what happens if there is low partial pressure of carbon dioxide in the alveoli ? - Bohr effect

Answer 4

curve shifts to the left, increased affinity and therefore uploads more oxygen

Question 5

what happens if there is high partial pressure of carbon dioxide at respiring tissues ? - Bohr effect

Answer 5

curve shifts to the right, decreased affinity and therefore unloads more oxygen

Question 6

what happens to the curve of a dove ?

Answer 6

faster metabolism, so needs more oxygen for respiration to provide energy for contracting muscles

Question 7

what happens to the curve of an earthworm ?

Answer 7

underground there is lower partial pressure of oxygen

Question 8

oxyhaemoglobin dissociation curve

Answer 8

oxygen is loaded in regions with a high partial pressure of oxygen and is unloaded in regions of low partial pressure of oxygen

Question 9

gas exchange surface e.g. alveoli
oxygen conc:
carbon dioxide conc:
affinity of haemoglobin for oxygen:
result:

Answer 9

oxygen conc: high
carbon dioxide conc: low
affinity of haemoglobin for oxygen: high
result: oxygen is attached - loads

Question 10

respiring tissues
oxygen conc:
carbon dioxide conc:
affinity of haemoglobin for oxygen:
result:

Answer 10

oxygen conc: low
carbon dioxide conc: high
affinity of haemoglobin for oxygen: low
result: oxygen is released - unloads

Question 11

affinity of haemoglobin for oxygen - define

Answer 11

readily associates (binds) with oxygen at the surface where gas exchange takes place (high PO2)

Question 12

saturation of haemoglobin with oxygen - define

Answer 12

when haemoglobin is holding maximum of oxygen it can bind

Question 13

what is loading ?

Answer 13

when the first oxygen molecule binds to the haem group and distorts shape of the whole molecule and so the other 3 molecules is taken up at increasing rate

Question 14

what is unloading ?

Answer 14

• the opposite happens
  the oxygen detaches and unbinds from haemoglobin

Question 15

cooperative binding

Answer 15

haemoglobin changes shape when first oxygen binds making it easier for further oxygen

Question 16

explain why the curves are S - shaped ?

Answer 16

this is called a sigmoid
if the curve shifts to the right, low affinity
if the curve shifts to the left, high affinity

Question 17

why is it that when the greater the conc of CO2, more readily haemoglobin released oxygen ?

Answer 17

dissolved CO2 is acidic and the low pH causes haemoglobin to change shape so making it more likely to give up its oxygen

Question 18

how does CO2 end up to the cells ? - haemoglobin

Answer 18

mammals respire releasing CO2 and H20 as a waste product
the carbon in CO2 binds to the hydrogen = carbonic acid this decreased the pH
an increase in oxygen levels = equilibrium into the cells why ? - haemoglobin changes shape - O2 unload

Question 19

what does the increase in oxygen levels cause the Bohr shift to do ?

Answer 19

sigmoid shifts to the right

Question 20

myoglobin

Answer 20

found in muscle cells and ensures that the high oxygen demand of muscles is met
one subunit so there is no cooperative binding
curve

Question 21

foetal haemoglobin

Answer 21

• the haemoglobin of a mammalian foetus has a high affinity for oxygen that that of adult haemoglobin
• this allows the foetal haemoglobin to pick up oxygen from an environment that would normally cause adult
  haemoglobin into release 02
• this causes the oxygen curve for the foetal haemoglobin to be the left to the curve for adult haemoglobin