adult & fetal haemoglobin

• What does the oxygen dissociation curve show?

  the rate at which oxygen associates, and also dissociates, with haemoglobin at different partial pressures of oxygen (pO2)
• What does the partial pressure of oxygen mean?

  the pressure exerted by oxygen within a mixture of gases; it is a measure of oxygen concentration
• What does it mean when haemoglobin is referred to as saturated?

  all of its oxygen binding sites are taken up with oxygen; so when it contains four oxygen molecules
• What does haemoglobin's affinity for oxygen mean?

  The ease with which haemoglobin binds and dissociates with oxygen
• When haemoglobin has a high affinity for oxygen what occurs?

  it binds easily and dissociates slowly
• What occurs when haemoglobin has a low affinity for oxygen?

  it binds slowly and dissociates easily
• what is another difference between fetal and adult haemoglobin?


  adult haemoglobin has 2 beta chains attached to 2 alpha chains

  but fetal haemoglobin has 2 gamma chains attached to 2 alpha chains

  leading to a different conformational structure
• what do the gamma subunits do in fetal haemoglobin?


  increase the affinity of the haemoglobin, thus the haemoglobin can readily bind to oxygen that is present in the mother's blood

  crucial to maintaining healthy development of the foetus