7.1 Haemoglobin
,Structure of haemoglobin molecule
• Haemoglobins are similar across a range of organisms: all have this
same basic structure…
• Has a quaternary structure, built up from primary [amino acids]
secondary [helixes] tertiary [precise 3d shape = necessary to
load/unload O2] quaternary [4 polypeptides linked, each associate
to a haem group Fe2+]
,Loading and unloading O2
• Loading, or associating, is when haemoglobin binds with O2 in the
lungs/alveolar capillaries
• Unloading, or dissociating, is when haemoglobin releases O2 into th
tissues in capillaries
• Haemoglobins with high affinity for O2 = load O2 more easily but
struggle to unload it, whereas low affinity = harder to load O2 but
easier to unload
, The role of haemoglobin
• Transport O2
• Need to be efficient by readily associating in lungs during gas
exchange, and readily dissociating in the tissues
• To do this, haemoglobin changes its affinity for oxygen based on th
conditions e.g. level of CO2 as they change the shape of the molecu
changes
High CO2 – CO2 dissolves in plasma – lowers pH – conformational
change in haemoglobin -
,Structure of haemoglobin molecule
• Haemoglobins are similar across a range of organisms: all have this
same basic structure…
• Has a quaternary structure, built up from primary [amino acids]
secondary [helixes] tertiary [precise 3d shape = necessary to
load/unload O2] quaternary [4 polypeptides linked, each associate
to a haem group Fe2+]
,Loading and unloading O2
• Loading, or associating, is when haemoglobin binds with O2 in the
lungs/alveolar capillaries
• Unloading, or dissociating, is when haemoglobin releases O2 into th
tissues in capillaries
• Haemoglobins with high affinity for O2 = load O2 more easily but
struggle to unload it, whereas low affinity = harder to load O2 but
easier to unload
, The role of haemoglobin
• Transport O2
• Need to be efficient by readily associating in lungs during gas
exchange, and readily dissociating in the tissues
• To do this, haemoglobin changes its affinity for oxygen based on th
conditions e.g. level of CO2 as they change the shape of the molecu
changes
High CO2 – CO2 dissolves in plasma – lowers pH – conformational
change in haemoglobin -
