haemoglobin

Question 1

haemoglobin structure

Answer 1

a group of chemically similar molecules
protein with a quaternary structure
four polypeptides are joined together.
each polypeptide has a haem group with a Fe2+ attached and a single O2 for each fe2 ion

Question 2

what is the role of haemoglobin

Answer 2

to transport oxygen

Question 3

how is haemoglobin effcient at transporting oxygen

Answer 3

readily associates with oxygen at the surface where gas excahnge takes place
readily disassociate with oxygen at the tissues that require it
this is achieved through affinity - it achieves this because its shape changes under certain conditions such as an increase in cabon dioxide concentration

Question 4

oxygen dissociation curves (shallow start of curve)

Answer 4

the shape of haemoglobin makes it difficult for the first 02 molecule to bind because the four sites are closely united therefore under low 02 conc not much binds causing the shallow start to the curve.

Question 5

oxygen disassociation curves (second haem)

Answer 5

the binding of the first molecule causes the quat structure to change shape making it easier to bind to a site
therefore it requires a smaller increase in partial pressure of 02 than the first one (positive cooperativity)

Question 6

effects of co2 concentration (low)

Answer 6

at the exchange surface the co2 conc is low as it has diffused across the exchange surface and been excreted from the organism.
oxygen has a high affinity for haemoglobin so is readily loaded by haemoglobin.
the reduced co2 causes the graph to shift left

Question 6

fourth haem

Answer 6

it is now harder for the last haem to bind to the oxygen molecule as there are 3 occupied sites
the curve reduces and graph flattens off

Question 7

effects of co2 concentration (high)

Answer 7

in rapidly respiring tissues the conc of co2 is high
oxygens affinity for haemoglobin is reduced meaning oxygen is readily unloaded from the haemoglobin in these tissues
shifting the curve to the right

Question 8

loading transport and unloading of oxygen

Answer 8

at the gas exchange surface co2 is constantly being removed
the pH is slightly raised due to the low conc of co2
the higher pH causes the change in shape in haemoglobin into one enabling 02 to be loaded readily
the shape change also increases affinity of haemoglobin for o2
in the tissues co2 is produced from respiring cells
ph lowers
this changes shape and affinmity of hamoglobin
haemoglobin releases its oxygen to respiring tissues