The Variety Of Life Flashcards
How many haem groups are in one molecule of haemoglobin?
4 haem groups, each one containing a Fe2+ ion, which is why 4 O2 molecules can be carried by one haemoglobin molecule
Where does haemoglobin have a high and low affinity in the body?
- high affinity = lungs, haemoglobin associates with O2
- low affinity = muscles, haemoglobin disassociates from O2
What is partial pressure?
The amount/ concentration of O2 in the blood
In an area where there is low/high conc of CO2 what is the affinity for O2?
High CO2: low affinity
Low CO2: high affinity
What type of haemoglobin will an organism with a low metabolic rate & that lives in an environment with little O2 have?
Haemoglobin that readily combines with O2 to absorb enough to survive
What type of haemoglobin will an organism that lives in an environment with plenty of O2 and has a high metabolic rate have?
Haemoglobin that releases oxygen easily
Why do different haemoglobins have different affinities for O2?
Different haemoglobin molecules have slightly different sequences of amino acids =different tertiary structures
What is the purpose of partial pressure?
Determines haemoglobin’s affinity for O2
What is an oxygen dissociation curve?
Shows the relationship between haemoglobin saturation with oxygen (the % of oxyhaemoglobin)
How many O2 atoms bind to one haemoglobin?
8 - one molecule is O2
What are the two advantages of the four globules in a haemoglobin molecule?
each globule…
- provides correct environment for O2 to bind to haem
- haemoglobin soluble in cytoplasm of red blood cell
How may human haemoglobins differ from other species?
- diff number of haem groups
- diff sequence amino acids on polypeptide chains
Explain co-operative binding
- first O2 molecule binds to haemoglobin
- this alters shape
- second O2 molecule binds more easily
Why is the O2 dissociation curve S-shaped?
Co-operative binding
What happens at the beginning (bottom) of the O2 disassociation curve?
Haemoglobin lets go of O2
What happens at the end (top) of the O2 dissociation curve?
Haemoglobin is highly saturated with O2, takes it up
What does the steepness of the O2 disassociation curve show?
The sensitivity of haemoglobin - a slight change in partial pressure triggers a rapid uptake/ dropping of O2
Explain how the respiring cells in muscle tissue affect haemoglobins affinity for O2
- respiring cells produce CO2
- CO2 dissolves in water to form Carbonic acid
- this is broken down, to produce H+ ions & hydrogen carbonate ions
- H+ ions = low pH
- if left in blood will poison
- haemoglobin drops O2 to bind H+ ion to haem group and carries it away to lungs to be exhaled
What is the Bohr-Shift?
The shifting to the right of the O2 disassociation curve
When does the Bohr-Shift occur?
During exercise - curve at resting point shifts right so the % of haemoglobin saturated decreases showing more O2 being released
What does the gap between the two curves (resting curve & Bohr Shift curve) represent?
The difference shows the additional O2 released from oxyhaemoglobin at any particular point
What other factors of exercise trigger the Bohr-Shift?
- acidic (low) pH
- high lactic acid conc
- increased temp
What is the advantage of the Llama having a curve shifted to the left of the Sheep?
- llama lives in high altitude
- partial pressure of O2 is low
- llamas haemoglobin has higher affinity for O2 than sheep
Why could a mutation in one of the genes coding for haemoglobin lead to a decrease in oxygen-carrying capacity of the blood?
- mutation = different base sequence, codes for different amino acids
- change in primary structure = change in tertiary structure
