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One blood cell contains about 280 million molecules of haemoglobin What is this?

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Presentation on theme: "One blood cell contains about 280 million molecules of haemoglobin What is this?"— Presentation transcript:

1 One blood cell contains about 280 million molecules of haemoglobin What is this?

2 Lesson Objectives (E) What are haemoglobins and what is their role? (C) How do haemoglobins from different organisms differ and why? (C) What is loading and unloading of oxygen?

3 Haemoglobin Globular protein. Quarternary structure. Two alpha + 2 beta chains. Haem group at centre of each tertiary structure (contains a ferrous ion Fe 2+ ). Each haem group carries one molecule of O 2. So Hb + 4O 2 HbO 8 oxyhaemoglobin To be efficient haemoglobin must –Readily pick up O 2 at the gas exchange surface. –Readily release O 2 at those tissues requiring it.

4 Hypochromic Anemia What happens if we have an iron deficiency?

5 Complete the table by adding high or low to the blanks Region of body Oxygen concentration Carbon dioxide concentration Affinity of haemoglobin for oxygen Result Gas exchange surface Oxygen is attached Respiring tissues Oxygen is released Affinity of haemoglobin under different conditions

6 Region of body Oxygen concentration Carbon dioxide concentration Affinity of haemoglobin for oxygen Result Gas exchange surface HighLowHighOxygen is attached Respiring tissues LowHighLowOxygen is released

7 Different Haemoglobins Different organism have different haemoglobins, this depends upon the organisms metabolism and environment. –Haemoglobins with a high affinity for oxygen. These take up oxygen more easily but release it less readily –Haemoglobins with a low affinity for oxygen. These take up oxygen less readily but release it more readily

8 What animals do you think would have a haemoglobin with a high affinity for oxygen? And a low affinity for oxygen?

9 Lesson Objectives (E) What is an oxygen dissociation curve? (C) What is the effect of carbon dioxide on the curve and why? (A/B) How do the properties of the haemoglobins in different organisms relate to the environment and the way of life of the organism concerned?

10 Oxyhaemoglobin dissociation curve

11 Oxygen dissociation curves S-shaped curve – because shape of molecule is altered as each O 2 molecule is taken up. After binding of first molecule shape changes so the binding of the others is easier. Steep part of the curve - small decrease in pp oxygen results in a big fall in Hb saturation, so that oxygen is released to the tissues where need is greatest.

12 P O 2 (mmHg)% saturation of haemoglobin Table 1. the percentage saturation of haemoglobin with oxygen at different partial pressures of oxygen Plot a graph of P O 2 against the percentage saturation of haemoglobin. The curve obtained is called the oxygen haemoglobin dissociation curve.

13 Questions

14 The Bohr effect (shift) CO 2 reduces the ability of Hb to combine with O 2. CO 2 present at respiring tissues – so Hb releases O 2.

15

16 South American Llamas live at high altitudes. Where do you think their oxygen dissociation curve would lie?

17 Llamas – high altitude, little O 2. Need higher affinity Hb – picks up O 2 more readily, but releases it less readily. Curve also shifted to left for other organisms inhabiting low O 2 environments – only releasing O 2 when pp very low.

18 Higher affinity haemoglobins 1.Foetal haemoglobin – has higher affinity than maternal Hb, so can obtain O 2. 2.Myoglobin – red pigment in mammalian muscles. Has a higher affinity for O 2 than Hb – only releasing it a very low pp. Myoglobin ‘STORES’ O 2.

19 Altitude sickness Caused by acute exposure to low partial pressure of oxygen at high altitude Compensated by altitude acclimatisation – body combats it by producing more red blood cells.

20 What animals would have a haemoglobin with a low affinity for oxygen and why? What would their curve look like?

21 Smaller animals (shrews/mice) and birds have curves shifted to the right. Have high metabolism so need O2 to be released readily.

22

23 Lesson Objectives (E) What are haemoglobins and what is their role? (C) How do haemoglobins from different organisms differ and why? (C) What is loading and unloading of oxygen?

24 Lesson Objectives (E) What is an oxygen dissociation curve? (C) What is the effect of carbon dioxide on the curve and why? (A/B) How do the properties of the haemoglobins in different organisms relate to the environment and the way of life of the organism concerned?


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