Download Biology Notes: Haemoglobin Structure, Function, and Oxygen Transport and more Quizzes Cell Biology in PDF only on Docsity!
What is the structure of haemoglobin?
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
What is the role of haemoglobin and how is it
efficient?
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
How does haemoglobin load and unload
oxygen?
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
Why do we have different haemoglobins?
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
How can we interpret oxygen dissociation
curves?
DEFINITION 5
The further to the left the curve, the greater the
haemoglobin's affinity for oxygen
The further to the right the curve, the lower the
haemoglobin's affinity for oxygen
How does carbon dioxide concentration affect
haemoglobin?
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
What is starch?
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
How is starch adapted for storage?
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
What is glycogen?
DEFINITION 9
Similar structure to starch but chains are shorter and it is
more branched
It animals it is stored as small granules in the muscles
and liver
It is even more readily hydrolysed to alpha glucose
because of the shorter chains
TERM 10
What is cellulose?
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
What are the differences between plant and
animal cells?
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
What is the function of root hair cells?
DEFINITION 17
They are exchange surfaces in plants that are responsible
for the absorption of water and mineral ions
They remain functional for a few weeks before dying back
and being replaced by others growing near the tip
TERM 18
How do root hair cells absorb water?
DEFINITION 18
By osmosis
High concentration of water in soil solution and low
concentration of water in root hair cells
TERM 19
How do root hair cells absorb mineral ions?
DEFINITION 19
By active transport
Concentration of minerals inside the root hair cell is
greater than concentration in soil solution
Carrier proteins use ATP to transport ions across the cell
membrane and to the root hair cell's cytoplasm and
vacuole
TERM 20
How is the xylem adapted for water
transport?
DEFINITION 20
Long tubes with no end for continuous water flow
No cytoplasm or organelles for easier water flow
Thick with lignin to withstand tension and keep water in
cells
Pits in the walls to allow lateral movement and get across
blocked vessels
