haemoglobin Flashcards
what is a quaternary structure?
two or more polypeptide chains
why is haemoglobin used to transport oxygen in the blood?
because oxygen solubility in water is very low
how any polypeptide chains does haemoglobin have?
4
what is the prosthetic group in haemoglobin ?
haem group (Fe2+)
what is another name for red blood cells?
erythrocytes
how many oxygen molecules does one haem group bind to?
1
what is the maximum number of oxygen molecules a haemoglobin can bind to?
4, 1 per haem group
how MUST haemoglobin do in order to be efficient at transporting oxygen?
readily associate with oxygen (in the lungs) and readily dissociate oxygen at respiring tissues
does haemoglobin always bind to 4 oxygen molecules?
no, it may also bind to 1,2 or 3 oxygen molecules
what is percentage saturation?
amount of oxygen bound to haemoglobin
give the formula of percentage saturation
oxygenated haemoglobin/maximum saturation x100
what is cooperative bonding?
when the first oxygen molecule binds to haemoglobin it alters the tertiary structure of the haemoglobin making it easier for the 2nd and 3rd oxygen to bind
what is partial pressure of oxygen?
the proportion of oxygen in a mixture of gases or solution
what is the shape of the oxygen dissociation curve?
sigmoidal
what is meant by the term affinity?
chemical attraction
where is the pO2 high at where is it low?
high at the lungs, low at the respiring tissues
what happens at the lungs?
- high pO2
- haemoglobin has a higher affinity for oxygen
- haemoglobin becomes almost fully saturated (98%)
what happens at respiring tissues?
- low pO2
- hamoglobin has a lower affinity for oxygen
- oxyhaemoglobin begins to break down
what is the dissociated oxygen used for?
aerobic respiration
what is the effect of increased respiration rate on oxygen dissociation?
- aerobic respiration-reduces O2 in tissue fluid
- reduces pO2
- oxygenated blood unloads more oxygen due to lower affinity
what is Bohr shift?
- if pO2 saturation increases, saturation oh Hb decreases
- Hb has a lower affinity for oxygen
- dissociation curve shifts to the right
what is the effect of CO2 on oxygen dissociation?
- CO2 dissolves in the blood and makes it more acidic
- lowers the pH
- alters the tertiary structure of Hb
lower affinity to O2
what is the relationship between surface area to volume ratio of mammals and their oxygen dissociation curves?
- smaller mammals have a greater S.A : V ratio so more heat is lost per unit body mass
- smaller mammals have greater rate of respiration
- oxygen required for aerobic respiration
- Hb releases more oxygen-so has a lower affinity
what causes variations in Hb affinity?
mutations
foetal haemoglobin and haemoglobin in organisms living at high altitudes/bottom of lakes has a ________ affinity for oxygen
higher
curve shifts to the right
becomes fully saturated at lower pO2
which organisms have Hb which has a curve shifted to the right?
very active animals or small animals that lose het through a large S.A :V ratio
why do organisms with a high metabolic rate have a curve shifted to the right?
- Hb has a lower affinity foe O2
- so dissociates readily so more O2 is available for aerobic respiration
what is haemoglobin?
a protein
how many haemoglobin molecules does one red blood cell contain?
approx. 300 million
