haemoglobin

what is haemoglobin?

water soluble protein w/ a quaternary structure

→ 4 polypeptides each containing a haem group

what is a haem group?

[Fe]²⁺

how many oxygens can bond to one haemoglobin?

4; one per haem group

what does high partial pressure of oxygen mean?

high concentration of oxygen

high affinity for oxygen meaning?

high likelihood of binding to it

when is oxygen loaded?

when partial pressure is high

when is oxygen unloaded?

when partial pressure is low

what regions have low partial pressure of oxygen?

respiring tissues

→ beneficial as oxygen unloads as required due to higher carbon, and lower oxygen conc.

what is the oxyhemoglobin dissociation curve?

curve showing % of saturated haemoglobin molecules at different partial pressures

what does it mean when the curve is shifted to the left?

oxygen is being loaded

no. saturated molecules increased

typically in alveoli

what does it mean when curve is shifted to the right?

oxygen is being unloaded

no. saturated molecules is lower

bohr effect

typically in alveoli

what’s the bohr effect?

increasing CO2 conc. shifts OHD curve right

• blood CO2 conc, increases due to respiration

• decreasing blood pH

• affinity for O2 decreases as acidity changes Hb tertiary structure slightly

• leading to faster unloading of O2 to respiring cells at given pO2

what is cooperative binding?

haemoglobin shape changes to make it easier/harder for oxygen to bind

how is the cooperative binding of haemoglobin shown in the curve?

initially hard for first O to bind

once it does, shape changes slightly making it easier for the further oxygens to bind

this sudden increase in binding oxygen as it is now easier, causes a sudden steepness in the curve

do all animals have the same type of haemoglobin?

no, they have dif types, with dif affinities for oxygen, which acts as an adaptation for their environments

RBC adaptations?

no nucleus - space for haemoglobin

biconcave - greater SA:V ratio + shorter diffusion distance

when is haemoglobin saturation low?

in respiring tissues where pO2 is low

affinity for O2 low

O2 unloads

when is haemoglobin saturation high?

in gas exchange surfaces where pO2 is high

affinity for O2 is high

O2 loaded

evidence for cooperative nature?

when partial pressure low, as O2 conc. increases, there is a slow increase in % saturation of Hb when O2 is first binding

when partial pressure is high, and O2 conc. increases, there is a rapid increase in % saturation of Hb, as it is easier for O2 to bind

advantages of bohr effect during exercise?

O2 unloaded more

faster aerobic respiration

more ATP produced

how do dif types of haemoglobin have dif O2 loading properties?

dif types have dif amino acid sequences

so dif tertiary/quaternary structure

so dif affinities for O2