CELL MEMBRANE

  • Active transport : It is the transport of a solute across a membrane in the direction of increasing concentration involving the expenditure of energy.

  • Amphipathic : It refers to liquid molecules having both hydrophobic (water hating) and hydrophilic (water loving) ends.

  • Autolysis : It is the process of self destruction of a cell by the release of lysosomic enzymes in the cell itself.

  • Autophagy : It is the process by which unwanted substances within the cell are removed.

  • Basal body : Centriole structure near the cell membrane from which Cilia and flagella develop. It is also called blepharoplast.

  • Cell : The smallest unit of life having a complex internal structure. The identity of various cellular components and functions of different structures have been studied with the help of electron microscope.

  • Cell theory : Doctrine initiated by Theodar Schuann in 1838 that all organisms are made up of cells and their products.

  • Cell wall : Semi-rigid permeable structure composed of cellulose lignin etc. that envelopes the plasma membrane in the cell of algae, bacteria, fungi and plants (animal cells have no cell wall).

  • Cellulose : A complex carbohydrate which consists of a chain of glucose molecules present in the cell wall of plants except fungi.

  • Centriole : A minute granular self replicating body from which astral rays and spindle fibres arise forming a spindle during cell division.

  • Centrosome : A small clear cytoplasmic body containing contriole(s), situated just outside the nuclear membrane in animal cell and helps in spindle formation.

  • Chlorophyll : Green pigments of plants which is meant for capturing solar energy of the sun during photosynthesis.

  • Chromoplast : Coloured plastids containing pigments other than chlorophyll.

  • Chromosomes : They are the carriers of heredity units of genes.

  • Cilium : (pl. cilla) : Minute hair like protoplasmic process arising from the cell surface.

  • Cristae : The folds of inner membrane of mitochondria protecting towards the inner side.

  • Cyclosis : Generation of cytoplasmic current by the action of microfilaments.

  • Cytoplasm : Protoplasmic material of cell not including the nucleus and its contents.

  • Cytoplasmic matrix : The protein of cell protoplasm not contained within the endomembrane system. It is called cytoplasm.

  • Cytoskeleton : Complex cytoplasmic network of microtubules and microfilaments located predominantly near the cell membrane and thought to be responsible for shell shape and movement.

  • Dalton : Unit of molecular weight, one Dalton equals one twelfth of mass of carbon 12.

  • Dictyosome : Organelle in the plant cell consisting of stacks of membrane sacks and vesicles that enclose and store cell product.

  • Diffusion : The movement of molecules or ion resulting from their kinetic energy that tends to disperse them throughout the medium.

  • Electrogradient : The differences between electric charges between two sides of membrane.

  • Endoplasmic reticulum : A system of channels and tubes in the cytoplasm which functions as site of protein synthesis and transport.

  • Euchromatin : The chromatin that constitutes bulk for the chromosome and contains the active genes.

  • Facilitated diffusion : A substance first combines with the carrier protein without use of energy in the cell membrane and then it diffuses across the membrane.

  • Flagellum (pl. flagella) Microscopic thread like protoplasmic extension of the cell surface.

  • Gel : Quasi solid state of (colloidal) matter.

  • Gene : A unit of genetic information.

  • Glycogen : A Polysaccharide related to starch (present mostly in animals) made up of many glucose sub-units and generally acts as a reserved food material.

  • Golgi body : A cytoplasmic organelle in the animal cell consisting of a stack of coarse membranes that enclose and store cell products.

  • Grana : Thyalokoids packed like pale of coins.

  • Granum (pl grana) : Discoid stack of membranes containing chlorophyll.

  • Heterokaryon : It is a hybrid cell.

  • Hetrocromatin : Chromatin rich in RNA responsible for nucleic acid metabolism.

  • Hyaloplasm : Cytoplasm without cell organelle.

  • Hypertonic : A solution having a higher concentration of solute molecules and a lower concentration of solvent molecules (water) than that of solution to which it is compared.

  • Hypotonic : A solution having a lower concentration of solute molecules and a higher concentration of solvent molecules than that of solution to which it is compared.

  • Incipient plasmolysis : The point at which plasmolysis just starts.

  • Isotonic : A solution having the concentrations of a solute and solvent water molecules exactly equal to that in another solution to which it is compared.

  • Lamella : A thin ribbon like structure present in the chloroplast.

  • Lignin : A complex organic substance in the wall of woody plants cells that lends strength to them.

  • Lysosome : Single membranous bag like organelle containing digestive enzymes also called suicidal bag.

  • Melanin : Dark coloured pigment in animals found mostly in skins.

  • Middle lamella : Layer which holds the neighbouring cells together and is made up of magnesium and calcium pectate.

  • Nucleus : Principal organelle of eukaryotic cell that is bounded by a membrane. It contains nucleoplasm and chromosomes. Genes present on chromosomes control the structure of proteins within the cell. Most of the cells are uninucleate and few multinucleate.

  • Osmoregulation : The process by which a cell or an animal controls the amount of water and the concentrations of various solutes and ions in the body.

  • Osmotic Pressure : The force that a dissolved substance exerts (by virtue of motion of its molecules) on a semipermeable membrane through which it cannot pass.

  • Peroxisome : Membrane enclosed organelle containing enzymes for hydrogen peroxide metabolism.

  • Phagocytosis : It refers to intake of solid particles by the cell.

  • Phagocytosis : Process of engulfment of large sized solid food particles by the cell through the plasma membrane.

  • Phospholipid : A group of fatty compounds composed of phosphoric esters such as lecethin.

  • Pinocytosis : Process of intake of a fluid food material by the cell through plasma membrane.

  • Plasmalemma : The living membrane surrounding a cell, also referred to as plasma membrane. Physiologically, it is semipermeable.

  • Plasmolysis : The shrinkage of protoplasm in cell due to removal of water by exosmosis.

  • Polysome : It refers to a cluster of ribosomes connected by common strand of messenger RNA.

  • Protista : A major category of living organisms including algae except (blue green) slime moulds, protozoan fungi.

  • Quantasome : It refers to a spherical body present in thyalcoid and capable of carrying out photochemical reactions.

  • Ribosome : Cytoplasmic organelles containing RNA and protein in approximately 1 : 1 ratio, site of protein synthesis.

  • Stroma : Colourless watery matrix surrounding the lamellae in cholorplast where dark reactions of photosynthesis occur.

  • Suberin : It is a water proof material secreted by core cells.

  • Tonoplast : Limiting membrane of a vacuole in a cell.

  • Tonoplast : The membrane surrounding the vacuole. Physiologically semipermeable.

  • Tonoplast : The membrane which surrounds the vacuoles in a plant cell.

  • Vesicle : Single membrane bound organelle.

  • Zymogen granule : A precursor of digestive enzyme which readily produces enzymes later on.