Haemoglobin Flashcards
(37 cards)
Describe the protein structure of Hb. Include details of prosthetic groups.
Quaternary protein structure.
Contains 4 prosthetic haem (Fe2+) groups in each of the 4 polypeptide chains.
State the 3 IMFs/interactions present in the quaternary protein structure.
Disulfide bridges
Hydrogen bonds
Hydrophilic/hydrophobic interactions
Where does loading of oxygen occur and why?
Lungs.
High concentration of oxygen.
Where does unloading of oxygen occur and why?
Muscles.
Low concentration of oxygen, muscles require it for respiration.
What is loading/unloading?
Loading is the addition of oxygen to Hb.
Unloading is the loss of oxygen from Hb.
What is oxygen affinity?
How well a molecule is able to take up Hb.
If a Hb molecule has low oxygen affinity, what does this mean for loading/unloading?
Oxygen is taken up less easily.
It is released from Hb more easily.
If a Hb molecule has high oxygen affinity, what does this mean for loading/unloading?
Oxygen is added to the Hb more easily.
Oxygen is harder to lose from Hb.
Which 2 gases are able to alter the shape of Hb?
Why?
Gradual addition of oxygen Hb leads to changes in the shape of it.
Carbon dioxide also changes the shape of it as it is acidic. It makes the Hb bind more loosely to the oxygen, so oxygen is lost more easily.
Why are there different haemoglobins for different species?
What does this mean for oxygen affinity?
Different species produce different amino acid sequences, leading to different tertiary/ quaternary structures
Different Hb molecules will have different oxygen affinities.
Name the graph used to show how Hb associated with oxygen.
Oxygen dissociation curve.
What shape are oxygen dissociation curves typically?
S - Shaped
Why is the binding of the oxygen to the 1st Hb molecule difficult?
The polypeptide chains in the Hb molecules are closely united.
Explain why its more easy for the 2nd/3rd oxygen to bind to the Hb.
Name the affect that causes this.
The binding of the first oxygen changes the shape of the Hb. This makes it easier for other oxygen molecules to bind.
Positive cooperativity.
Explain why it is more difficult for the 4th oxygen to bind to the Hb.
Probability makes it harder for oxygen to bind as there is only 1 free binding site, so there is less chance of the oxygen finding a free space to bind.
What is partial pressure?
The concentration of oxygen in the body.
What does it mean if an oxygen dissociation curve is further left?
There is a higher affinity for oxygen.
What does it mean if an oxygen dissociation curve is further right?
There is a lower affinity for oxygen.
What happens when partial pressure is higher in the lungs?
There is more oxygen association.
What happens when partial pressure is lower in tissues?
Leads to more oxygen dissociation in the lungs.
In the lungs, partial pressure is higher.
State the Hb oxygen affinity, concentration of CO2 (high/low) and whether O2 associates or not.
High oxygen affinity.
Low CO2 concentration.
O2 associates.
In tissue, partial pressure is lower.
State the Hb oxygen affinity, concentration of CO2 (high/low) and whether O2 associates or not.
Low Hb O2 affinity.
High CO2 concentration.
O2 dissociates.
What must happen for O2 to be transported efficiently?
Hb must be readily available at exchange surfaces and oxygen must dissociate readily at aerobically respiring tissues.
Why does Hb have lower affinity for oxygen in the presence of CO2?
Presence of CO2 suggests that is is an aerobically respiring tissue that requires a supply of oxygen.
