Haemoglobin

Haemoglobin
Haemoglobin is a protein with several important
properties:
It is found in red blood cells where it has a vital role in
oxygen transport
It is a protein with a quaternary structure because it is
made from the four polypeptide chains
It has a remarkable ability to pick up oxygen where it is
abundant and released it where it is needed…read more

Haemoglobin is a protein making up
to 95% of the dry mass of the red
Hb + 40 Hb0
blood cells. Haemoglobin binds with
(associate with) oxygen in the
lungs where the concentration
(partial pressure) of oxygen is
high. Haemoglobin then travels
around the body and unbinds
(dissociates with) oxygen when
the particles pressure of oxygen
is low.
Each haem group can combine with
one oxygen molecules, so that one
molecules of haemoglobin can
combine with the maximum of four
oxygen molecules. This is called
oxyhaemoglobin.…read more

The key point about haemoglobin There are two key features of
is not that it can pick up oxygen- the oxygen dissociation
lots of substances can do that but curve:
that it can release it again in areas
where it is needed. At a high oxygen concentration
(found in the lungs) where the
The polypeptide chains of curve is level, haemoglobin
haemoglobin effect the affinity it becomes almost saturated with
has for binding oxygen. oxygen
Polypeptide chains can have slight At a low oxygen concentration
differences in their primary (found in tissue) where the curve
sequences or polypeptide folding is steep, oxyhaemoglobin
can be altered by changing the pH dissociates
or temperature.
The behaviour of haemoglobin
with oxygen is illustrated by the
oxygen dissociation curve.…read more

Oxygen Dissociation
Curve
Describe: Explanation:
When the partial pressure of oxygen is
low, the saturated of haemoglobin is It is difficult for the first oxygen
also lo. Haemoglobin has only bound molecule to bind to haemoglobin
to a small amount of oxygen. because of the shape folding of
As the partial pressure of oxygen is the polypeptide chains. Once the
increasing, the percentage saturation first molecule has to
of haemoglobin is also increasing. The haemoglobin the change in shape
haemoglobin is binding to more that this causes makes it easier
oxygen. The line is very steep which
means that small changes in partial for more oxygen to bind.
pressure makes big increases in the Haemoglobin has bonded to as
percentage of haemoglobin . much oxygen as it can so the line
As the partial pressure of oxygen is high, becomes constant.
the percentage saturation of
haemoglobin levels of to become
constant at a high point nearly 100%…read more

Carbon dioxide on 0 dissociation
This graph shows how haemoglobin binds oxygen in different concentration of CO.
Putting haemoglobin in high levels of CO the curve is shifted to the right. This is
called Bohr Shift.…read more

The effects of exercise Overall, this means that
when the CO
Carbon dioxide is produced when concentration are high,
you respire as a product given more oxygen is released.
off by the respiring muscles.
This carbon dioxide dissolves This is good because
in the blood plasma and oxygen is needed for
produces an acidic solution respiration.
which cause some of the
hydrogen bonds to brake. This
leads to the haemoglobin
protein shape (this is
reversible)…read more