biologival molecules

• Triglycerides are used as energy reserves in plant and animal cells.
• Phosphate heads are hydrophilic and the tails are hydrophobic and as a result phospholipids form micelles when they are in contact with water as heads are on the outside as they are attracted to water and tails are on the inside as they move away from water.
• Lipids are biological molecules which are only soluble in organic solvents such as alcohols.
• Unsaturated lipids which can be found in plants contain carbon-carbon double bonds and melt at lower temperatures than saturated fats, making them healthier as they provide essential fatty acids.
• Some triglycerides contain a mix of different fatty acids.
• Microfibrils are strong threads which are made of long cellulose chains joined together by hydrogen bonds and they provide structural support in plant cells.
• Saturated lipids such as those found in animal fats don’t contain any carbon-carbon double bonds and excessive consumption can increase the cholesterol levels in blood, increasing the risk of coronary heart disease.
• Triglycerides are non-polar and hydrophobic molecules composed of one molecule of glycerol and three fatty acids joined by ester bonds formed in condensation reactions.
• Sucrose is a disaccharide formed by condensation of glucose & fructose.
• In phospholipids, one of the fatty acids of a triglyceride is substituted by a phosphate-containing group.
• Lactose is a disaccharide formed by condensation of glucose & galactose.
• There are many different types of fatty acids, they vary in chain length, presence and number of double bonds.
• Maltose is a disaccharide formed by condensation of two glucose molecules.
• Cellulose is a component of cell walls in plants and it’s composed of long, unbranched chains of beta glucose which are joined by glycosidic bonds.
• Polysaccharides are formed from many monosaccharides joined together by glycosidic bonds and include Glycogen and starch which are both formed by the condensation of alpha glucose.
• Benedict’s solution can be used to test for the presence of reducing sugars, which include all monosaccharides and some disaccharides.
• Collagen is a fibrous protein of great strength due to the presence of both hydrogen and covalent bonds in the structure.
• The tertiary structure of proteins is the 3D shape of the protein, it can be globular or fibrous.
• Haemoglobin carries oxygen in the blood and has a quaternary structure consisting of 2 alpha subunits and 2 beta subunits.
• There are 20 different amino acids with different R groups.
• The quaternary structure of proteins consists of 2 or more subunits (polypeptide chains) closely packed together.
• Collagen forms the structure of bones, cartilage and connective tissue and is a main component of tendons which connect muscles to bones.
• Haemoglobin is a water soluble globular protein.
• Water has a high specific heat capacity meaning that a lot of energy is required to warm water up therefore minimising temperature fluctuations in living things.
• Water is a polar molecule due to uneven distribution of charge within the molecule – the hydrogen atoms are more positive than the oxygen atom causing one end of the molecule to be more positive than the other.
• Peptide bonds can be hydrolysed (broken) with the addition of water in a hydrolysis reaction.
• The shape of proteins is determined by the type of bonding present such as: hydrogen bonding, ionic bond, disulphide bridges, and tertiary structure.
• The oxygen can bind to the haem group and be released when required.
• The primary structure of a protein is the order and number of amino acids in a protein.
• A dipeptide contains two amino acids and polypeptides contain three or more amino acids.
• Collagen molecules wrap around each other and form fibrils which form strong collagen fibres.
• Water acts as a solvent in which many metabolic reactions occur.
• Amino acids are joined by peptide bonds formed in condensation reactions.
• Water acts as a metabolite in metabolic reactions such as condensation and hydrolysis which are used in forming and breaking of chemical bonds.
• The test involves heating the sugar with Benedict’s solution, and if the colour changes from blue to brick red, then glucose is present.
• Amino acids are the monomers from which proteins are made.
• Water has a relatively large latent heat of vaporisation , meaning evaporation of water provides a cooling effect with little water loss.
• Globular proteins such as enzymes are compact and soluble, whereas fibrous proteins such as keratin are long and insoluble.
• The secondary structure of proteins is the shape that the chain of amino acids chains – either alpha helix or beta pleated sheet.
• Each polypeptide chain in haemoglobin contains a prosthetic (non-protein) group - haem (Fe2+).