Key Terms (Cells)
Protoplasm : Is all the living parts of a cell.
Ultrastructure : The fine detail of a cell as seen as with an electron microscope.
Chromatin : Name given to chromosomes when they are not dividing.
Ribosomes : Very small organelles made of protein and RNA. The function is to make proteins.
Organelles : Distinct structures suspended in cytoplasm.
Prokaryotic cells : Cells do not have a nuclear membrane surrounding their DNA. Eg – Monera
Eukaryotic cells : These cells have a membrane-bound nucleus and organelles.
Tissue : A group of similar cells specialised to carry out the same function.
Tissue culture : Cells grown on a sterile nutrient medium outside an organism.
Organ : A structure, containing different tissues, which has a specific function.
Organ system : A group of organs and tissues working together to carry out a specific function.
Catalyst : A substance that speeds up the rate of a chemical reaction(metabolism) without itself taking part in the reaction.
Enzymes : Defined as biological catalysts, protein in nature. Enzymes speed up the reactions in the cell without being used up in the reaction.
Substrate : The substance an enzyme reacts with.
Product : Is formed when an enzyme reacts with a substrate.
Active site : The region of the enzyme that binds with the substrate.
Denatured enzyme : An enzyme which has lost its shape and can no longer carry out its function.
Bioprocessing : Use of enzyme-controlled reactions to produce a product.
Bioreactor : A vessel used to carry out enzyme controlled reactions.
Batch processing : Fixed amount of nutrients added at beginning and emptied at the end of production.
Immobilised enzymes : Enzymes that are fixed/attached to each other or to an inert material.
Phosphorylation : Addition of phosphate to a molecule.
Protease : An enzyme which digests protein.
Cell continuity : All cells develop from pre-existing cells.
Chromosome : Coiled threads of DNA and protein that become visible in the nucleus at cell division.
Haploid cell : A cell which contains one of every chromosome type or pair.
Diploid cell : A cell which contains two of each type of chromosome (in homologous pairs).
Homologous pair : Consists of 2 chromosomes that each have genes for the same features at the same positions.
Interphase : The phase in the cell cycle when the cell is not dividing.
Mitosis : A form of cell division that produces two daughter cells, genetically identical to each other and to the parent cell.
Meiosis : A form of cell division that produces four genetically different daughter cells, each of which has half the number of chromosomes of the parent cell.
Cancer : Group of disorders in which certain cells lose their ability to control both the rate of mitosis and the number of times mitosis takes place.
Selectively permeable : Cell membranes allow the passage of some materials but not others.
Diffusion : The movement of a substance from its area of higher concentration to its area of lower concentration. (Passive process)
Active transport : The movement of a substance(usually ions) from its area of lower concentration to its area of higher concentration. (Opposite of diffusion)
Osmosis : The diffusion of water across a selectively permeable membrane, from its area of higher concentration to its area of lower concentration.
Hypotonic sol : Has a low concentration of solutes and thus a higher concentration of water than another solution.
Hypertonic sol : Has a higher concentration of solutes and thus a lower concentration of water than another solution.
Isotonic sol : Has the same concentration of solutes and water as another solution.
Turgor / Turgor pressure : Is the pressure of the cytoplasm and vacuole against the cell wall.
Phagocytosis : Process where large particles are engulfed by the cell and become incorporated into a vacuole within the cell.