3.1 Biological molecules AQA A Level Biology
- Created by: lucieannwhite
- Created on: 01-06-18 19:20
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- Biological molecules
- Monomers and polymers
- What are they?
- Polymers are molecules made from a large number of monomers joined together
- Monomers are the smaller units from which larger molecules are
made
- Monosaccharides, amino acids and nucleotides are examples of monomers
- Condensation
- A condensation reaction joins two molecules together with the formation of a chemical bond and involves the elimination of a molecule of water
- Hydrolysis
- A hydrolysis reaction breaks a chemical bond between two molecules and involves the use of a water molecule
- What are they?
- Carbohydrates
- Saccharides
- Mono=one A single sugar molecule. e.g. Glucose, galactose and fructose
- Di = two A condensation reaction between two monosaccharides forms a
glycosidic bond and a disaccharide
- maltose is a disaccharide formed by condensation of two glucose molecules
- sucrose is a disaccharide formed by condensation of a glucose molecule and a fructose molecule
- lactose is a disaccharide formed by condensation of a glucose molecule and a galactose molecule
- Poly = many Polysaccharides are formed by the condensation of many glucose units
- Glycogen and starch are formed by the condensation of alpha-glucose
- Cellulose is formed by the condensation of beta-glucose
- Glucose
- Glucose has two isomers
- alpha-glucose
- ?-glucose
- Glucose has two isomers
- Saccharides
- Lipids
- Triglycerides
- formed by the condensation of one molecule of glycerol and three molecules of fatty acid
- A condensation reaction between glycerol and a fatty acid (RCOOH)
forms an ester bond
- Phospholipids
- one of the fatty acids of a triglyceride is substituted by a phosphate-containing group
- Phospholipids
- Phospholipids
- one of the fatty acids of a triglyceride is substituted by a phosphate-containing group
- The R-group of a fatty acid may be saturated or unsaturated
- Saturated = no double carbon bond (c=)
- unsaturated = contains a double bond (c=)
- the emulsion test for lipids
- Triglycerides
- Proteins
- General properties of proteins
- Amino acids are the monomers from which proteins are made
- need to know the structure
- peptide=one dipeptide=two polypeptide=many
- A condensation reaction between two amino acids forms a peptide bond
- A functional protein may contain one or more polypeptides
- hydrogen bonds, ionic bonds and disulfide bridges maintain the structure of proteins
- Many proteins are enzymes
- Each enzyme lowers the activation energy of the reaction it catalyses
- models of enzyme action
- Lock and key theory
- Induced fit model
- How they form complexes?
- the active site of the enzyme is complementary in shape to the substrate
- factors affecting this
- enzyme concentration
- substrate concentration
- pH
- calculate pH, using the formula: pH = ?log10 H+
- Temperature
- inhibitors
- the biuret test for proteins
- General properties of proteins
- Monomers and polymers
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