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Definitions and explanations about the structure, function, and efficiency of haemoglobin, including its role in oxygen transport, oxygen loading and unloading, different types of haemoglobins, and oxygen dissociation curves. Additionally, it covers the relationship between carbon dioxide concentration and haemoglobin, as well as an introduction to starch, glycogen, and cellulose.
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Primary structure - sequence of amino acids in four chains of amino acids Secondary structure - coiled into a helix, 2 alpha 2 beta Tertiary structure - chain folded into precise shape to allow it to carry oxygen Quaternary structure - four polypeptide chains linked to form an almost spherical molecule. Each is associated with a haem group which contains iron which combines with a single oxygen. TERM 2
DEFINITION 2 Transport oxygen To be efficient, it must readily associate at gas-exchange surfaces and dissociate at respiring tissues Haemoglobin changes its affinity for oxygen under different conditions because its shape changes in the presence of certain substances In the presence of CO2, haemoglobin changes shape and binds more loosely with oxygen so it is more easily dissociated TERM 3
DEFINITION 3 First oxygen binds to a haem group so distorts the shape of the haemoglobin molecule so the second, third and fourth oxygen molecules are taken up increasingly quickly Fourth oxygen molecule is taken up several hundred times more quickly than the first At respiring tissues with low pO2, first oxygen is released very quickly but others are released much more slowly TERM 4
DEFINITION 4 Haemoglobins with a high affinity for oxygen take up oxygen quickly but release it less readily and vice versa Organisms living in environments with little oxygen require haemoglobin with a high affinity for oxygen provided their metabolic rate is not very high , so the body can absorb enough oxygen but does not use it up too quickly Organisms with high metabolic rate need haemoglobin with a low affinity for oxygen so it is dissociated quickly and they receive the evergy they require Lugworm's are not very active but live in areas with low pO2, so they need a high affinity for oxygen Mice have a large SA:V ratio so lose heat rapidly and need a high metabolic rate to compensate for their temperature regulation Haemoglobins have different affinities for oxygen because they have different shapes because they have slightly different base sequences and therefore a different arrangement of amino acidics in their primary structures TERM 5
DEFINITION 5
Haemoglobin has a reduced affinity for oxygen in the presence of CO The Bohr Effect: Tthe greater the concentration of CO2, the more rapidly haemoglobin releases its oxygen When CO2 dissolves in the blood, it produces carbonic acid which lower pH values Low pH causes oxygen to dissociate more quickly Curve shifts to the right TERM 7
DEFINITION 7 Polysaccharide Found in plants as small grains, especially in storage organs like potato tubers Major energy source for food Made up of chains of alpha glucose monosaccharides linked by glycosidic bonds that are formed by condensation reactions Unbranched chain is wound into a tight coil that makes the molecule very compact Two types: Amylose (20%) which is unbranched with a 1, glycosidic bond, and Amylopectin (80%) which is branched with 1,4 and 1,6 glycosidic bonds TERM 8
DEFINITION 8 Starch is suited for storage because: It is insoluble and therefore does not affect osmosis It is insoluble so does not easily diffuse out of cells It is compact so lots is stored in a small space When hydrolysed it forms alpha glucose which is easily transported and used in respiration The human equivalent of starch is glycogen TERM 9
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DEFINITION 10 Made of monosaccharides of beta glucose rather than alpha glucose To form glycosidic links, each beta glucose molecule must be rotated by 180 degrees compared to its neighbour so the -CH2OH group alternates between being above and below the chain Does not form a coiled chain like starch, but forms straight, unbranched chains Chains run parallel to one another so hydrogen bonds form cross- links between them Hydrogen bonds are very weak but the sheer number of them strengthens cellulose Cellulose moleculesare grouped together in microfibrils which are arranged in parallel groups called fibres
Cellulose cell wall surrounds the cell as well as well- surface membrane Only cell-surface membrane surrounds the cell Chloroplasts are present in large numbers in most cells Chloroplasts are never present Normally hav a large central vacuole filled with cell sap If vacuoles are present they are small and scattered throughout the cell Starch grains are used for storage Glycogen granules are used for storage TERM 17
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