Bio

• Biological Molecules contain Monomers and polymers.
• Condensation and hydrolysis reactions are important in carbohydrates.
• Monomosaccharides and disaccharides are important in carbohydrates.
• Isomers of glucose, such as α- and β-glucose, are important in carbohydrates.
• Polysaccharides are important in carbohydrates.
• Biochemical tests are important in carbohydrates.
• Lipids contain triglycerides and phospholipids.
• Triglycerides and phospholipids contain saturated and unsaturated fatty acids.
• The emulsion test is used to distinguish between lipids.
• Many proteins are enzymes.
• Factors affecting the rate of enzyme-controlled reactions include temperature, pH, and concentration of substrate and enzyme.
• The structure of DNA and RNA nucleotides and polymers is important in nucleic acids.
• DNA replication is a process in nucleic acids.
• The process of DNA replication involves the formation of Okazaki fragments.
• Evidence for semi-conservative replication was provided by Meselson and Stahl.
• ATP is important in biological molecules.
• Sodium is involved in the co-transport of glucose and amino acids across cell membranes, and is involved in generating nerve impulses and muscle contraction.
• Pond skaters are a type of insect that use solvents such as water to separate ionic compounds like NaCl into positive and negative ends.
• Inorganic ions occur in solution in the cytoplasm and body fluids of organisms, with some in high concentrations and others in very low concentrations.
• Water acts as a medium for metabolic reactions and as a transport medium, for example, in xylem to transport nitrates which are needed to make amino acids.
• Each type of ion has a specific role, depending on its properties, and these roles are relevant in a range of topics across the A Level.
• Iron is a component of the haem group of haemoglobin which is contained in red blood cells, transporting oxygen around the body, with oxygen temporarily binding to it, so it becomes Fe3+.
• Hydrogen maintains pH levels in the body, with too much H+ leading to acidic (low pH) and too little H+ leading to alkaline (high pH).
• Water is polar, has a slightly positive and negative ends, and can separate ionic compounds like NaCl as the positive end is attracted to the negative ion (Cl-) and the negative end is attracted to the positive ion (Na+).
• Water is reactive and condensation releases H2O and forms a chemical bond, while hydrolysis requires H2O to break a bond.
• Water can dissolve other substances like inorganic ions, enzymes, urea, etc.
• Phosphate is attached to other molecules as a phosphate group, for example, in DNA nucleotides, enabling nucleotides to join together forming phosphodiester bonds, and in ATP – bonds between these store/release energy.
• At a certain point, the rate of reaction plateaus.
• Enzyme concentration is the limiting factor when all active sites are saturated; excess substrate.
• Non-competitive inhibitors decrease the rate of reaction by binding to a site away from the active site (allosteric site).
• Fewer E-S collisions and E-S complexes occur when the pH is too high or too low.
• Enzymes denature and the tertiary structure and active site change shape when the temperature is too high.
• A complementary substrate can no longer bind to the active site when the pH is too high or too low.
• Substrate concentration is the limiting factor when there are too few enzyme molecules to occupy all active sites.
• Limiting factor in a chemical reaction is the substrate concentration.
• Increasing the temperature above the optimum rate of reaction causes the rate of reaction to fall.
• pH above or below the optimum pH rate of reaction decreases.
• Increasing the temperature up to the optimum rate of reaction increases the rate of reaction.
• Competitive inhibitors decrease the rate of reaction by competing for, binding to, or blocking the active site so substrates can’t bind.
• Increasing the substrate concentration of a reaction increases the rate of reaction.