4- transport of gases in blood

Question 1

structure of haemoglobin

Answer 1

• composed of four polypeptide chains: two alpha chains and two beta chains
• each chain has a haem group with an iron atom, which can bind to one molecule of oxygen
• one haemoglobin molecule can carry up to four oxygen molecules

Question 2

role of haemoglobin in gas exchange

Answer 2

• haemoglobin transports O2 from the lungs to tissues and CO2 from tissues to the lungs
• oxygen transport: oxygen binds to the iron in the haem groups, forming oxyhaemoglobin
• carbon dioxide transport: some carbon dioxide is carried in the bloodstream bound to haemoglobin (carbaminohaemoglobin)

Question 3

Bohr affect on haemoglobin

Answer 3

• the effect of pH on the oxygen- binding affinity of haemoglobin
• high pH (low carbon dioxide concentration): leads to a higher affinity for oxygen, facilitating oxygen uptake in the lungs
• low pH (high carbon dioxide concentration): leads to a lower affinity for oxygen, facilitating oxygen release in respiring tissues

Question 4

oxygen dissociation curve

Answer 4

• a graph showing the relationship between oxygen pressure (PO2) and the oxygen- carrying capacity of haemoglobin
• sigmoidal shape: indicates that as the oxygen pressure increases, more oxygen binds to haemoglobin until it becomes fully saturated
• left shift: occurs at higher pH levels, lower temperatures, or lower carbon dioxide levels- this signifies a higher affinity of haemoglobin for oxygen
• right shift (bohr effect): occurs at lower pH levels, higher temperature, or higher carbon dioxide levels, this signifies a lower affinity of haemoglobin for oxygen

Question 5

myoglobin structure

Answer 5

• single polypeptide chain with 153 amino acids
• contain one heme (iron containing) group

Question 6

function of myoglobin

Answer 6

• stores oxygen in muscle cells, releasing it during periods of hypoxia or intense exercise

Question 7

myoglobin vs haemoglobin

Answer 7

• haemoglobin is a tetramer, with four polypeptide subunits. myoglobin is monomeric
• haemoglobin transports oxygen in the blood from the lungs to the tissues. myoglobin stores oxygen in muscle cells

Question 8

myoglobin oxygen affinity

Answer 8

myoglobin has higher oxygen affinity than adult haemoglobin, to store oxygen effectively

Question 9

structure of foetal haemoglobin

Answer 9

• composed of two alpha and two gamma chains
• contains two heme groups

Question 10

function of foetal haemoglobin

Answer 10

transports oxygen from mothers bloodstream to the foetus

Question 11

foetal haemoglobin vs adult haemoglobin

Answer 11

• adult haemoglobin is made up of two alpha and two beta chains. foetal haemoglobin has two alpha and two gamma chains
• foetal haemoglobin has a higher oxygen affinity than adult haemoglobin, facilitating effective oxygen transfer from mother to foetus

Question 12

oxygen affinity in foetal haemoglobin

Answer 12

higher than adult haemoglobin, to effectively extract oxygen from the mothers blood