Haemoglobin Flashcards
what are the haemoglobins?
a group of chemically similar molecules found in a wide variety of organisms
haemoglobin is globular - what does this mean?
round
compact
easily soluble
the haemoglobin structure is curled up - what does this mean?
the hydrophillic side chains face inwards.
this makes the molecule soluble so good for transport in the blood
finish the equation:
Hb + 4O2
4Hb(O2)
what is the tertiary structure of haemoglobin?
each polypeptide chain is folded into a precise shape for carrying oxygen
what is the quaternary structure of haemoglobin?
4 polypeptides linked together to form an almost spherical molecule
what is each polypeptide in haemoglobin associated with?
a haem group
what does a haem group contain?
Fe 2+
what can each Fe 2+ combine with?
What does this mean?
O2
4 O2s can be carried by one haemoglobin molecule
define partial pressure
a measure of the concentration of a gas, taking into account air pressure
e.g. high pO2 in lungs, low pO2 in muscles
define affinity
the tendency of a chemical substance to react with another chemical substance
what does haemoglobin’s affinity for oxygen depend on?
pO2
how does O2 bind in a high affinity?
easily
define loading/association in terms of haemoglobin
O2 associates with haemoglobin to form oxyhaemoglobin when there is a high pO2
define unloading/dissociation in terms of haemoglobin
O2 unloads from oxyhaemoglobin when there is a low pO2
define saturation in terms of haemoglobin
how much oxygen is being carried (%)
Finish the sentence:
Haemoglobins with a high affinity for oxygen…
take up oxygen more easily, but release it less easily
Finish the sentence:
Haemoglobins with a low affinity for oxygen…
take up oxygen less easily, but release it more easily
what is the role of haemoglobin?
to transport oxygen
how is haemoglobin efficient at transporting oxygen?
readily associates with oxygen at the gas exchange surfaces
readily dissociates from oxygen at tissues requiring oxygen
what allows both dissociation and association?
a change in affinity
what aspect of how haemoglobin binds with oxygen makes it a good transporter?
it binds reversibly
where in the body has a high pO2?
gas exchange surfaces
where in the body has a low pO2?
respiring tissues
what is haemoglobin like in other species?
different species have different amino acid sequences so slightly differently shaped haemoglobins. This affects the affinity
