Haemoglobin Text p The haemoglobins are a group of chemically similar molecules found in many different organisms. Haemoglobin is a protein with a quaternary structure.

Homework Text p.151 red 2 nd lesson p.155 red Find out about foetal haemoglobin – how does a foetus gain oxygen from its mother? Present on A4 paper (oxygen dissociation graph and explanation)

Did you know? 1 litre of water can hold 25ml of oxygen 1 litre of blood can carry 200ml. THAT’S 8 TIMES AS MUCH.

Objectives 1.What are haemoglobins and what is their role? 2.How do haemoglobins from different organisms differ and why? 3.What is loading and unloading of oxygen? 4.What colour is haemoglobin compared to oxyhaemoglobin?

Haemoglobin Each haem group can combine with one oxygen molecule, so that one molecule of haemoglobin can combine with a maximum of four oxygen molecules. This forms oxyhaemoglobin. Haemoglobin is a protein making up 95% of the dry mass of a red blood cell. It is the means of transport of oxygen around the body. polypeptide chain Haemoglobin is made up of four polypeptide chains, each bound to one haem group.

Student modelling Use playdoh to make a haemoglobin molecule

Haemoglobin molecules p150 Questions 1.How would you describe ‘Haemoglobins’? 2.Explain how haemoglobin has each level of protein structure. 3.What is a haem group, and what does it do? The haem group is known as a prosthetic group joined to the protein chain. Haem unit

Structure of Haemoglobin Primary Sequence of amino acids in a poypeptide chain Secondary In which each of these polypeptide chains is coiled into a helix or pleated. Tertiary In which each polypeptide chain is folded into a precise shape – an important factor in it’s ability to carry oxygen Quaternary In which all four polypeptides are linked together to form an almost spherical molecule. Each unit is associated with a haem group (which contain Fe 2+ that can combine with 1 O 2 molecule). Total – 4 O 2 molecules.

The Role of Haemoglobin p What 2 properties must haemoglobin have to be efficient at transporting oxygen? 2.How does haemoglobin achieve these 2 things? 3.Under what conditions does haemoglobin attach to oxygen? 4.Describe the conditions under which oxyhaemoglobin releases oxygen.

The Role of Haemoglobin p What 2 properties must haemoglobin have to be efficient at transporting oxygen? 2.How does haemoglobin achieve these 2 things? 3.Under what conditions does haemoglobin associates with oxygen? 4.Describe the conditions under which oxyhaemoglobin dissociates with oxygen. 1.Combine/associate with oxygen and dissociate or release oxygen 2.Hb changes its affinity for oxygen under different conditions because it changes its shape slightly 3.Associates more readily with oxygen when high conc. Oxygen (and low carbon dioxide) 4.Dissociates in the presence of high carbon dioxide (and low oxygen)

Different types of haemoglobin Type of haemoglobin What it doesMetabolic rate Example of organism (write in name) High affinity for oxygen Associates with oxygen easily Dissociates with oxygen less readily Low in oxygen Low affinity for oxygen High in oxygen so doesn’t matter it is taken up less easily High – oxygen is released readily into respiring tissues

Different types of haemoglobin Type of haemoglobin What it does Environment of organism Metabolic rate Example of organism High affinity for oxygen Associates with oxygen easily Dissociates with oxygen less readily Low in oxygenNot very high so it doesn’t matter if oxygen isn’t released that readily Lugworm Low affinity for oxygen Associates with oxygen less easily but dissociates more readily High in oxygen so doesn’t matter it is taken up less easily High – oxygen is released readily into respiring tissues Pigeon/bird

Why do different Hbs have different affinities for oxygen 1.What did scientists find out about different organisms haemoglobin? 2.Why do they have different affinities for oxygen?

Loading and unloading oxygen The process by which haemoglobin becomes oxyhaemoglobin is called … or … When oxyhaemoglobin loses oxygen it is called … or … Each haemoglobin molecule can combine with … oxygen molecules; Hb + 4O 2  HbO 8

Loading and unloading oxygen The process by which haemoglobin becomes oxyhaemoglobin is called loading or associating. When oxyhaemoglobin loses oxygen it is called unloading or dissociating. Each haemoglobin molecule can combine with four oxygen molecules; Hb (dark red) + 4O 2  (bright red) HbO 8

Key words Affinity Associate/loading Dissociate/unloading More readily Less readily Saturated

Objectives 1.What are haemoglobins and what is their role? 2.How do haemoglobins from different organisms differ and why? 3.What is loading and unloading of oxygen? 4.What colour is haemoglobin compared to oxyhaemoglobin?