Molecular Bonding Condensation Reactions – a reaction that joins two molecules and H2O is removed Hydrogen Bond – A weak interaction between a slightly positively charged atom and a slightly negatively charged atom e.g. between the bases of DNA, between the O(-) of...
2.1.3 Enzymes (a) state that enzymes are globular proteins, with a specific tertiary structure, which catalyse metabolic reactions in living organisms All enzymes are globular proteins with a specific tertiary structure, which catalyse metabolic reactions in all...
Nucleic Acids The monomer units in nucleic acids are called nucleotides. They consist of a pentose sugar (deoxyribose/ribose) a phosphate group and a nitrogenous base that is either a pyrimidine or a purine. These three components are joined in condensation reactions...
Microscopes Light microscope – Light microscopes shine light through a specimen and then uses focused lenses to magnify it. Laser scanning microscope – These use laser light to scan an object, point by point, before using the information to assemble an image on the...
Cell Membranes (a) outline the roles of membranes within cells and at the surface of cells (b) state that plasma (cell surface) membranes are partially permeable barriers Plasma membranes are partially permeable meaning they let some molecules through but not...
Enzymes Biological Catalysts Enzymes are biological catalysts that speed up metabolic reactions and remain unchanged at the end of the reaction. The number of reactions that an enzyme can catalyse per second is known as the turnover number Active site- the indented...
Biological Membranes Plasma membranes are partially permeable as they allow some but not all substances to pass through them. Very small molecules diffuse through the plasma membrane Some substances dissolve in the lipid layer to pass through Larger substances pass...
Nucleotides and Nucleic Acids (a) state that deoxyribonucleic acid (DNA) is a polynucleotide, usually double stranded made up of nucleotides containing the bases adenine (A), thymine (T), cytosine (C) and guanine (G) Nucleic acids come in two forms: DNA...
Cell Structure (a) state the resolution and magnification that can be achieved by a light microscope, a transmission electron microscope and a scanning electron microscope Light Microscope - uses a number of lenses to produce an image that can be viewed directly at...
Cell Division, Cell Diversity and Cellular Organisation (a) state that mitosis occupies only a small percentage of the cell cycle and that the remaining percentage includes the copying and checking of genetic information (b) describe, with the aid of diagrams and...
Biological Membranes (a) outline the roles of membranes within cells and at the surface of cells (b) state that plasma (cell surface) membranes are partially permeable barriers Plasma membranes are partially permeable meaning they let some molecules through but not...