topic 1

• water is a polar molecule from having an uneven distribution of charge
• water is polar because their hydrogen atoms are slightly positive compared to the oxygen atoms (who are slightly negative).
• water being polar is useful for our metabolism because it is metabolite in a metabolic reactions (condensation and hydrolysis)
• water acts as a buffer as they have a high specific heat capacity
• water has a high latent heat of vaporisation
• water has strong cohesion between molecules which enables effective transportation. this give water high surface-tension
• water is less dense than ice. ice being more dense is beneficial to organic life as they are protected by an insulating layer.
• water is incompressible which provides good support
• biological molecules - nucleic acids, proteins, lipids and carbohydrates
• protein contains nitrate, carbon, oxygen, hydrogen and sulphur
• ATP is a non-cyclic photophosphorylation process which produced in the mitochondria in animal cells and chloroplasts in plant cells
• glycolysis occurs in the cytoplasm
• the first step in glycolysis is the breakdown of glucose into two pyruvic acid molecules
• macromolecules are large molecules that are made up of many smaller molecules. monomers are atoms that are linked together to make a polymer
• types of monomers - nucleotides, monosaccharides and amino acids
• condensation reaction is a reaction where monomers join by covalent bonding that get rid of water. hydrolysis reaction is a reaction where water is needed to break covalent bonds of 2 molecules
• in carbohydrates, monomers are called monosaccharides and polymers are called polysaccharides. when 2 monosaccharides are joined together they make a disaccharide. many monosaccharides that are joined together are called a polysaccharide
• polysaccharides and disaccharides are formed by glycosidic bonds
• types of sugars - hexose, triose, tetrose and pentose
• glucose has 2 isomers (alpha glucose and beta glucose).
• properties of glucose - small, soluble, less reactive
• alpha glucose + alpha glucose = maltose
• maltose is found in germinating seeds and broken down for energy
• alpha glucose + fructose = sucrose
• sucrose is transported through the phloem to provide sugar throughout the plant
• amylase can be broken down into smaller units by enzymes called amylae
• alpha glucose + galactose = lactose
• lactose is found in milk which help babies grow
• a glycosidic bond is a covalent bond formed by 2 monosaccharides by condensation reaction
• maltose is a bond formed between carbon1 and carbon4 which is called the 1,4 glycosidic bond
• true polysaccharides have more than 10 monosaccharides. polysaccharides that have less than 10 monosaccharides are called oligosaccharides
• glycogen has many branches so it's very soluble and easy to digest
• alpha glucose is the main source of energy in respiration. excess chemical energy is stored in cells that form polysaccharides of alpha glucose.
• alpha glucose polysaccharides are well suited as an energy store as: they are compact (there's a lot of energy stored in a small space), insoluble in water (so the cell wont burst), they are large (they cant go through the cell membrane), can be easily hydrolysed to alpha glucose when energy is needed.
• polysaccharides energy store is starch. starch is found in photosynthesising cells in leaves, storage organs and storage cells in seeds
• starch is compacted into dense, insoluble grains that are stored in the amyloplasts.
• amylose is found a lot in storage organs as they need to have a sufficient amount of startch/energy
• there are 2 types of starch polysaccharides - amylose and amylopectin. amylose has 1 slinky shape chain while amylopectin has a few individual slinky shaped chains
• amylose is a long chain of alpha glucose molecules that are joined together by 1,4 glycosidic bonds
• amylose coils into a helix shape that makes it more compact. amylose have 2 accessible ends where enzyme amylase can bind. amylose takes a while to break down