topic 2

• 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 tail 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.
• 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.
• Human Immunodeficiency Virus (HIV): A virus that attacks T cells in the immune system and can lead to AIDS (acquired immune deficiency syndrome).
• Lysosomes: Membrane-bound vesicles found in the cytoplasm that contain a hydrolytic enzyme called lysozyme.
• Magnification: How much bigger an image appears compared to the original object.

  Image size = Actual size X Magnification
• Mitochondrion: An organelle found in eukaryotic cells that is the site of aerobic respiration.
• Mitosis: The part of the cell cycle in which a eukaryotic cell divides to produce two daughter cells, each with identical copies of DNA.
• Monoclonal antibodies: Identical antibodies that have been produced by an immune cell that has been cloned from a parent cell.
• 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.
• 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.
• Passive immunity: A form of immunity provided by the introduction of antibodies to a disease into the body.
• Phagocytosis: The process where phagocytes engulf and destroy material.
• Plasmids: A circular loop of DNA found in the cytoplasm of bacterial cells.
• Primary immune response: The response produced by the immune system when it encounters a pathogen for the first time.
• Resolution: The ability to distinguish two different points in a specimen.
• Ribosomes: Organelles found either free in the cytoplasm or membrane bound that are involved in the synthesis of proteins.
• Rough endoplasmic reticulum (RER): A membrane-bound organelle that is involved in the synthesis and packaging of proteins.
• Secondary immune response: The response produced by the immune system when it recognises a pathogen that it has encountered before.
• 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.
• Smooth endoplasmic reticulum (SER): A membrane-bound organelle involved in lipid synthesis.
• Vaccine: The introduction of dead or inactive pathogens to stimulate an immune response and provide long term immunity.