3.2 describe the structure of carbohydrates, proteins and larger molecules made up from smaller basic units: starch and glycogen from simple sugars, proteins from amino acids, lipids from fatty acids and glycerol

~         Biological molecules: carbohydrates

-       Body’s main ‘fuel’ for supplying cells with energy

-       Starch is a large insoluble molecule. Starch is manufactured in the green leaves of plants from excess glucose produced during photosynthesis and serves the plant as a reserve food supply/ storage carbohydrate. Some plants that store glucose as starch: e.g. rice, barley, potato, wheat. Starch is made from a long chain of glucose molecules joined together. It is called a polymer of glucose. Monomer of starch: glucose. Starch is only found in plant tissues, but animal cells sometimes contain a very similar carbohydrate called glycogen, found in tissues where it acts as a store of energy.

-       Monosaccharaide: basic monomer units of carbohydrates. ‘Single’ sugars such as glucose and fructose are called monosaccharaides. 

-       Disaccharide: consist of 2 monosaccharaides joined by a glycosidic bond. Sucrose (table sugar) is made from 2 monosaccharaides (glucose and fructose) and is called a disaccharide. Lactose is also a disaccharide of glucose joined with a monosaccharaide galactose. Maltose is a disaccharide of glucose and glucose.

-       Polysaccharides: consist of thousands of monosaccharaides (monomers) linked by glycosidic bonds to form long chains. Polymers of monosaccharaides, e.g. starch and glycogen. 

~         Biological molecules: Lipids (fats and oils) 

-       Two types of molecule lipids are made of:glycerol and fatty acids

~         Biological molecules: proteins

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- The amino acids are linked together in long chains, usually folded up or twisted into spirals.

-       Monomers of proteins: Amino acids.

-       The shape of a protein is very important in allowing it to carry out its function. The order of amino acids and the number of amino acids in each protein decides the shape. As there are 20 different types of amino acids and the order and number of structures varies, there are thousands of different proteins in organisms.

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