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Flashcards in Haemoglobin Deck (9)
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What is haemoglobins

Are protein molecules with a quaternary structure that has evolved to make it efficient at loading oxygen under one set of conditions but unloading it under a different set of conditions


What’s the structure of haemoglobin

Primary - sequence of amino acids in the four polypeptide chains

Secondary - in which each of these polypeptide chains is coiled into a helix

Tertiary- in which each polypeptide chain is folded into a precise shape - an important factor in its ability to carry oxygen

Quaternary- in which all 4 polypeptides are linked together to form an almost spherical molecule. Each polypeptide is associated with a haem group - which contains a ferrous Fe ion. Making a total of 4 O2 molecules that can be carried by a single haemoglobin molecule in humans


What is loading (associating)

The process by which haemoglobin binds with oxygen. Takes place in the lungs


What is unloading (dissociating)

The process by which haemoglobin releases its oxygen

Takes place in the tissues


What’s the difference between haemoglobins with a high affinity for oxygen and a low affinity for oxygen

High affinity - take up oxygen more easily, but release it less easily

Low affinity - take up oxygen less easily, but release it more easily


The role of haemoglobin is to transport oxygen. Haemoglobin must do what to be efficient at transporting oxygen

Readily associate with oxygen at the surface where gas exchange takes place

Readily dissociate from oxygen at those tissues requiring it


What’s the oxygen concentration, co2 concentration, affinity of haemoglobin for oxygen and result in the gas exchange surface

Oxygen concentration- high

Co2 conc- low

Affinity- high

Oxygen is associated


What’s the oxygen concentration, co2 concentration, affinity of haemoglobin for oxygen and result in the respiring tissues

Oxygen concentration- low

Co2 conc- high

Affinity - low

Oxygen is dissociated


Why do different haemoglobins have different affinities for oxygen

Each species has a slightly different amino acid sequence. The haemoglobin of each species therefore had a slightly different tertiary and quaternary structure and hence different oxygen binding properties