Glossary

• Active immunity: A form of immunity provided by the immune response of the body upon detection of a pathogen
• Active transport: The active movement of substances from a low concentration to a higher concentration (up their concentration gradient) with the use of energy in the form of ATP
• Agglutination: The clumping together of cells or particles caused by antibodies which assists phagocytosis
• Antibody: A protein found in the blood that is produced by plasma cells which binds to antigens as a part of the immune response
• Antigen: Marker molecules that can be detected by antibodies and trigger an immune response
• Binary fission: The method of cell division used by prokaryotes involving replication of the circular DNA and plasmids followed by cytoplasmic division
• Cell cycle: The series of stages preparing the cell for division consisting of interphase and mitosis
• Cell-surface membrane: A phospholipid bilayer studded with proteins that surrounds cells and separates them from their environment
• Cell vacuole: A membrane bound structure found in plant cells that contains cell sap
• Cell wall: A permeable layer that surrounds plant, algae and fungi cells made of polysaccharides which provides strength to the cell
• Chloroplast: An organelle found in plants and algae that is the site of photosynthesis
• Clonal expansion: The production of many genetically identical daughter cells through cell division of the activated B or T lymphocyte after clonal selection
• Clonal selection: The process of matching the antigens on an antigen presenting cells with the antigen receptors on B and T lymphocytes
• Co-transport: A method of membrane transport where two substances are both transported across a membrane at the same time either in the same direction or opposite directions
• Cytokinesis: Division of the cytoplasm to produce two new cells
• Facilitated diffusion: The passive movement of substances from a high concentration to a lower concentration (down their concentration gradient) through transport proteins without the use of energy
• Flagella: A whip-like structure found on bacterial cells that is used for cell movement
• Fluid-mosaic model: A model that describes membrane structure as a sea of mobile phospholipids studded with various proteins
• Golgi apparatus: An organelle found in eukaryotic cells that is involved in the modification and packaging of proteins
• Helper T cell: A type of T cell in the immune system that stimulates cytotoxic T cells, B cells and phagocytes
• Osmosis: The passive diffusion of water molecules from a region of high water potential to a region of lower water potential (down a water potential gradient) through a selectively permeable membrane without the use of energy
• Primary immune response: The response produced by the immune system when it encounters a pathogen for the first time
• Vaccine: The introduction of dead or inactive pathogens to stimulate an immune response and provide long term immunity
• Lysosomes: Membrane-bound vesicles found in the cytoplasm that contain a hydrolytic enzyme called lysozyme
• Simple diffusion: The passive spreading out of substances from a high concentration to a lower concentration (down their concentration gradient) without the use of energy
• Plasmids: A circular loop of DNA found in the cytoplasm of bacterial cells
• Herd immunity: A type of disease immunity that occurs when a large proportion of a population are vaccinated against a disease which prevents the spread of the disease to unvaccinated individuals
• Phagocytosis: The process where phagocytes engulf and destroy material
• Mitochondrion: An organelle found in eukaryotic cells that is the site of aerobic respiration
• Passive immunity: A form of immunity provided by the introduction of antibodies to a disease into the body
• Nucleus: An organelle found in eukaryotic cells that stores the genetic information of the cell as chromosomes and is surrounded by a membrane called the nuclear envelope
• Human Immunodeficiency Virus (HIV): A virus that attacks T cells in the immune system and can lead to AIDS (acquired immune deficiency syndrome)
• Rough endoplasmic reticulum (RER): A membrane-bound organelle that is involved in the synthesis and packaging of proteins
• Ribosomes: Organelles found either free in the cytoplasm or membrane bound that are involved in the synthesis of proteins
• Magnification: How much bigger an image appears compared to the original object calculated using the following formula:
• Mitosis: The part of the cell cycle in which a eukaryotic cell divides to produce two daughter cells, each with identical copies of DNA
• Smooth endoplasmic reticulum (SER) : A membrane-bound organelle involved in lipid synthesis
• Secondary immune response: The response produced by the immune system when it recognises a pathogen that it has encountered before
• Resolution: The ability to distinguish two different points in a specimen
• Monoclonal antibodies: Identical antibodies that have been produced by an immune cell that has been cloned from a parent cell