Biological molecules

inorganic ions
1. Mg 2+
  1. important part of chlorophyll therefore essential for photosynthesis, plants without enough magnesium in their soil cannot produce chlorophyll and turn yellow (chlorosis) and growth can stunt, mammals need magnesium for their bones
2. Fe 2+
  1. important part of haemoglobin which transports oxygen in red blood cells, lack of iron in diet leads to anaemia
3. Ca 2+
  1. important structural component of bones and teeth in mammals and is a component of plant cell walls
4. PO4 3-
  1. used in making nucleotides such as ATP and the DNA bases A, C, G, T and U, also a part of phospholipids which are present in the membranes of cells
water
1. properties
  1. boils at 100 °C
  2. Freezes at 0°C
    1. expands when frozen
  3. moves based on water potential
  4. high latent heat of vaporization
  5. high specific heat capacity
2. significance
  1. product of aerobic respiration
  2. product of condensation reactions
    1. condensation reactions are reactions that form polymers and water as a product
  3. reactant in photosynthesis
  4. reactant in hydolysis
    1. hydrolysis is the breakdown of a compound when reacted with water
  5. necessary for regulating metabolism
  6. provides support (turgidity) and buoyancy
Carbohydrates
1. Monosaccharides
  1. triose
    1. contains 3 carbons
    2. only 3 possible trioses L/D-Glyceraldehyde (enantiomers/optical isomers) and Dihydroxyacetone (symmetrical so has no enantiomers)
    3. dihydroxyactone is a component of a molecule important in cellular respiration
    4. trioses intermediate in reactions of respiration and photosynthesis
  2. pentose
    1. 5 carbons
    2. 2 groups, aldopentoses with an aldehyde group (O=C-H) and ketopentoses with a keytone functional group (O=C)
    3. examples of aldopentoses are the deoxyribose part of DNA and the ribose part of RNA, ketopentoses are much rarer
  3. hexose
    1. Has 6 carbons
    2. 2 groups, aldohexoses (e.g glucose) and ketohexoses (e.g fructose)
    3. the only naturally occurring ketohexoses are fructose, psicose, sorbose and tagatose
  4. monosaccharides can act as: a source of energy in respiration, carbon-carbon bonds are broken to release energy which is transferred to make ATP building blocks for larger molecules, e.g glucose is used to make loads of molecules including starch, glycogen and cellulose intermediaries in reactions (see triose) parts/constituents of nucleotides (see pentose)
2. disaccharides
  1. sucrose
    1. glucose+fructose
    2. important in transport in phloem of flowering plants
    3. can be hydrolysed to separate it's glucose and fructose
  2. lactose
    1. glucose+galactose
    2. found in mamailian milk
    3. can be hydrolysed to separate it's glucose and galactose
  3. maltose
    1. glucose+glucose
    2. important in germinating seeds
    3. the glucose molecules can be separated by hydrolysis
  4. composed of two monosaccharides units bonded by a glycosidic bond (and removal of water) this can be reversed by hydrolysis
3. polysaccharides
  1. starch
    1. made of alpha glucose monomers bonded by glycosidic bonds
    2. used by plants to store glucose, starch is used because it is insoluble so has no effect on the water potential of the cell, starch also can't diffuse out of the cell
    3. found in high concentration in seeds and storage organs like potato tubers
    4. the alpha glucose is bonded in 2 different ways, as amylopectin and amylose. Amylose is an unbranded chain of 1,4 bonded monomers that coil into a helix, amylopectin is like amylose but has some 1,6 bonds on it's monomers that cause it to have other 1,4 bonded chains branching off it
  2. glycogen
    1. main storage product in animals
    2. very similar to amylopectin in starch however it has shorter alpha-1,4 linked chains so is more branched
  3. cellulose
    1. found in plant cell walls which makes it the most abundant organic molecule on earth
    2. consists of many long chains of beta glucose monomers bonded by 1,4 glycosidic bonds this bond rotates the adjacent monomers 180 degrees allowing it to form hydrogen bonds between adjacent parralel chains, between 60 and 70 cellulose molecules to form microfibrils, these microfibrils are in turn held in bundles called fibres, these fibres are freely permeable and run parralel in cell wall layers but at angles to adjacent layers
  4. chitin
    1. found in the exoskeleton of insects and in fungal cell walls
    2. resembles cellulose with chains of beta-1,4 linked monomers but has a group derived from amino acids to form a heteropolysaccharide
    3. can form microfibrils exactly like cellulose
lipids
1. triglycerides
  1. triglycerides are formed by the combination of one glycerol molecule and three molecules of fatty acid, the glycerol molecule is always the same however the fatty acid molecules can vary, the fatty acids join to the glycerol molecule by condensation reactions, in this reaction three molecules of water are removed and ester bonds (O=C) are formed between the glycerol and the fatty acids (this is a reversible reaction and can be reversed by hydrolysis)
  2. make up energy reserves in both plants and animals, thermal insulation under animal skin, protects vital organs in animals e.g kidneys produce lots of metabolic water (water released during chemical reactions in the body) when oxidized
2. phospholipids
  1. phospholipids are two fatty acid tails bonded to a phosphate head, the phosphate head is hydrophilic and the fatty acid tails are hydrophobic, this is because the phosphate head has oxygen molecules whereas the fatty acid tails have no oxygen molecules, this mix of polarities allows phospholipids to form the phospholipid bilayer that makes up cell membranes
3. effects of fats on human health
  1. saturated
    1. If a fat is saturated then it has only single carbon-carbon bonds, it solidifies readily and is likely a solid fat at room temperature
    2. If someone has a diet high in saturated fats low density lipoproteins (LDL's) build up and cause harm. Fatty material called atheroma gets deposited in the coronary arteries, restricting blood flow and thus restricting oxygen delivery to the heart. results in cardiovascular and coronary heart disease, causing medical conditions such as angina and myocardial infarction (heart attack)
  2. unsaturated
    1. If a fat is unsaturated that means that a carbon-carbon double bond is present so the chain forms a kink, the chains cannot arrange uniformly and the lipid doesn't solidify readily. this is why unsaturated lipids are oils which remain liquid at room temperature
    2. If a diet is high in unsaturated fats the body makes more high density lipoproteins (HDL's) which carries harmful saturated fats to the liver for disposal the higher the ratio of HDL:LDL the lower the chances of developing cardiovascular and coronary heart disease.
4. properties
  1. like carbohydrates, lipids contain carbon, hydrogen and oxygen but, in proportion to the hydrogen and oxygen , they contain much less oxygen. They are non polar but dissolve in inorganic solvents like propanone and alcohols
  2. properties of fats and oils are determined by the fatty acid tails present
5. waxes
  1. waxes are lipids that melt above about 45°C. They ave a waterproofing role in both animals (insect exoskeleton) and plants (in the cuticle of a leaf)
amino acids/proteins
1. protein structure
  1. primary
  2. secondary
  3. tertiary
  4. quarternary
  5. fibrous
  6. globular
2. amino acids
  1. R group
    1. This is a carboxyl group
    2. This is an amino group
  2. List of all amino acids

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Biological molecules

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	Created by Jack Bruce over 5 years ago