Oxygen dissociation curves show partial pressure of oxygen plotted against what If a species haemoglobin has a high affinity for oxygen what does this mean Why does CO 2 concentration alter Haemoglobins affinity for oxygen ID: 1041557
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1. Haemoglobin Quiz!How many oxygen molecules can one haemoglobin molecule carry?Oxygen dissociation curves show partial pressure of oxygen, plotted against what?If a species’ haemoglobin has a high affinity for oxygen, what does this mean?Why does CO2 concentration alter Haemoglobin’s affinity for oxygen?
2. 4% saturation of haemoglobin with oxygenIt associates easily and does not dissociate easilyDissolved CO2 is acidic – change in pH can alter tertiary structure of Hb
3. Oxygen Dissociation CurvesWhy is the curve that shape?Low p02 Hb subunits closely united, difficult for O2 to bindBinding of first O2 molecule induces the other subunits to bind to O2 – change in quaternary structure of HbSo smaller increase in p02 needed for second 02 to bind compared to first – positive cooperativityDifficult for last 02 to bind. Lower probability of p02 finding the single empty binding site.12/34
4. The effect of carbon dioxideCarbon dioxide lowers Hb’s affinity for oxygen.Dissolved carbon dioxide is acidic.How does this affect the position of the oxygen dissociation curve?
5. The Bohr effectCurve shifts to the rightAt high pCO2, for any given partial pressure, Hb saturation with oxygen is lower than at low pCO2
6. Different haemoglobinsDifferent species have different haemoglobinsSlightly different primary structuresDifferent affinities for oxygen, different dissociation curves
7. Lug wormsLug worms get oxygen from the waterWhen the tide is out, there is no new waterThe O2 level dropsThey must still respire!They have haemoglobin with a greater affinity for O2 than humans:They load oxygen more easily and release it less easily
8. Different dissociation curves
9. Different dissociation curvesWhy?
10. Different dissociation curvesWhy?Mouse is small so has larger SA:Vol.Loses heat easily.Replaces lost heat with high rates of respirationMore oxygen needed for higher rates of respiration
11. Haem Handout!Be prepared to get questions about unfamiliar organisms!Think about what you are told in the question… is the animal very active? Is it very small? Does it live in low O2 environment e.g. at altitude or in a closed burrow? Remember! shift to the right means lower affinity, shift to the left means higher affinityUse the examples in your text book to help you