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.