Haemoglobin Flashcards
What type of protein is haemoglobin
Globular
Why is it good that red blood cells do not contain a nucleus
Provides more space inside the cell for haemoglobin so that they can transport as much O2 as possible
What structure does haemoglobin have
Quaternary made up of 4 polypeptide chains
Describe the globin proteins in a haemoglobin
Four globin subunits are held together by disulphide bonds
Arranges so their hyrophobic R groups are facing inwards helping to preserve the three dimensional spheric shape
The hydrophilic R groups face outwards to maintain solubility
What does the haem group contain
Fe2+ which is able to reversibly combine with an oxygen molecules to form oxyhaemoglobin
How many oxygen molecules can be carried in a haemoglobin
Because of their four haem mgroups they can carry four oxygen molecules or 8 oxygen atoms
What is haemoglobins function
Binding oxygen in lungs and transporting the oxygen to the tissue to be used in aerobic metabolic pathways
Why can oxygen be carried efficiently
Oxygen isn’t very soluble in water and haemoglobin is
What does the Fe2+ allow when transporting haemoglobin
Allows O2 to be reversibly bind
No amino acids that make up the polypeptide chains in haemoglobin are well suited to binding with oxygen
What does the oxygen bind to
The haem groups
Whats another word for red blood cells
Erythrocytes
Equation for haemoglobins binding to oxygen
Oxygen + Haemoglobin <-> Oxyhaemoglobin
4O2 + Hb <-> Hb4O2
Process name of O2 binding
Cooperative bindig
Describe cooperative binding
Binding of first O2 molecule results in conformational change in the structure of the haemoglobin molecule
so its easier for each successive O2 to bind
How are red blood cells adapted for O2 transport
Red blood cells lack nuclei = more space for haemoglobin
Biconcave shape = high SA:V, so there is a short diffusion distance for O2
What does the oxygen dissociation curve show
Rate at which oxygen associated and dissociates with haemoglobin at different partial pressures of oxygen
Whats the partial pressure of oxygen meanign
Partial pressure of O2 refers to the pressure exerted by oxygen within a mixture of gases, a measure of oxygen concentration
What occues to O2 when haemoglobin has a higher affinity for oxygen
Haemoglobin can bind easily and dissociate slowly
Which way does the curve move for high and low CO2 affinity
High affinity = right
Low affinity = left
When is oxygen associated and where
Gas exchange surface
When O2 conc is high, CO2 conc is low and affinity of haemoglobin for O2 is high
When is oxygen dissociated and where
Repiring tissues
When O2 conc is low, CO2 conc high, and affinity of haemoglobin for O2 is low
Where does loading/ associating take place
In lungs
Where does unloading and dissociating take palce
Tissues
WHen do haemoglobins take up more O2 easily
Haemoglobin with high affinity for O2 = load easily and release less easily
Describe the quanternary structure of haemoglobin
Four polypeptides are linked to form a spherical molecule
Each polyppetide is associated with a haem group which contains Fe2+ and can combine with a single O2
How can substance X benefit endurance for athletes
Results in more red blood cells which means athletes have more haemoglobin
So more oxygen can be offloaded and absorbed
More ATP is released and used for muscle contraction
Delays anaerobic respiration
What structure protein is haemoglobin
Quaternary with four polypeptide chains two alpha globins and two beta globins, each with a prosthetic haem group
How are the four globin subunits held together
Disulphide bonds arranges with hydrophobic R group inwards and hydrophilic outwards
What does the prosthetic haem contain
Iron II ion (Fe2+)
Haemoglobins functions
-Oxygen binding and transporting
-Oxygen is insoluble in water but haemoglobin is soluble so can be caried efficiently
-Haem enables small molecueles to be bound more easily because each oxygen binds alters quaternary structure so other oxygen has higher chance of binding
-Iron II ion allows O2 to reversible bind
What two types of globin proteins make up the haem group
Two alpha globins and two beta globins
What is haemoglobins functions
1) binding O2 in lungs and transporting it to tissue for aerobic metabolic pathways
2) O2 not soluble inwater and haemoglobin is, O2 canbe carried more efficiently around the body
3) Existence of Fe2+ alows O2 to be reversible bind as amino acids arent well suited
WHat happens if haemoglobin decreases in the bloodq
Fewer haemoglobin so less O2 is delivered o muscles
Less O2 means reduces AEROBIC RESPIRATION
Which means less ATP available for muscle contraction, reducing muscle contraction
Advantage of someone having less haemoglobin if haemoglobin has a lower affnity for O2
(Graph shifts right) so haemoglobin has a lower affinity
Haemoglobin dissociates MORE oxygen
So oxygen is available for use in aerobic respiration
Demand for ATP can be met at lower haemoglobin concentrations
Roles of haemoglobin
1) transport oxygen to aerobic metabolic pathways
2) Removing CO2 from respiring tissues
3) Dissociating oxygen from haemoglobin at respiring tissues
Advantage of having a low affinity for O2
Dissociates at tissues more easily
So can have a greater rate of respiration
