112061
Description
Flashcards by sammi_taylor01, updated more than 1 year ago
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Created by sammi_taylor01
over 11 years ago
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| Question | Answer |
| If the amino acid sequence alters, what happens consequently to the polypeptide chain? | different sequence of amino acids, different primary structure and therefore different tertiary structure, different protein and so a different polypeptide chain |
| What is haemoglobin? | A group of protein molecules that have a quarternary structure |
| What four structures is haemoglobin made up of? | primary structure (PS), secondary structure (SS), tertiary structure (TS) and quarternary structure (QS) |
| Define the PS and SS of haemoglobin | PS-consists of four polypeptide chains. SS-polypeptide chains are all coiled into a helix. |
| Define the TS and QS of haemoglobin. | TS-each polypeptide chain is folded into a specific shape, important for it's ability to carry oxygen. QS-all polypeptides are linked together in an almost spherical molecule. |
| The QS is associated with what? | The haem group which contains an Fe2+ ion. |
| What's special about each Fe2+ ion? | They can each combine with one O2 molecule and transport O2 to respiring muscles around the body. Therefore 4 O2 molecules can be carried round the body at once by one molecule |
| What is the role of haemoglobin? | To transport oxygen round the body |
| For haemoglobin to be efficient, it must: | -readily associate oxygen at the surface where gas exchange takes place -readily dissociate oxygen to the tissues requiring it (respiring tissues) |
| How does haemoglobin release oxygen more readily in the presence of CO2? | The presence of CO2 causes the haemoglobin molecule to change shape slightly, therefore binding to the O2 molecule more loosely, enabling it to unload the oxygen more readily. |
| What are two types of haemoglobin? Describe them. | -Haemoglobins with high affinity for O2 (readily take it up, release less readily) -Haemoglobins with low affinity for O2 (take it up less easily, readily release) |
| What type of haemoglobin is required for an organism living in an environment with low oxygen concentrations? | High affinity for oxygen, they need to be able to easily bind with as much oxygen as they can in order to absorb enough of it. |
| What type of haemoglobin is required for an organism living in an environment with high concentrations of oxygen? | Low affinity for oxygen, as then it can readily release the oxygen to respiring tissues, if there is enough of it in the air it does not need to easily pick it up. |
| What's the reason for different haemoglobins having different affinities for oxygen? | Slightly different sequence of amino acids and therefore a slightly different shaped molecule. |
| What's the process called where haemoglobin binds with oxygen? Where does this take place? | 1- loading, associating 2- in humans takes place in the lungs. |
| What's the process called when oxygen is released from the haemoglobin molecule? Where does this take place? | 1-unloading, dissociation 2- in humans takes place in the respiring tissues. |
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