VCE Biology Unit 3 Glossary Terms- Chapter 1

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Question Answer
active transportMovement of substances across membranes that requires the expenditure of energy; occurs through selective protein channels
biomacromoleculeLarge organic molecules formed by joining together many smaller units (monomers) to form a chain or polymer, for example polysaccharides, nucleic acids and proteins.
carbohydrateOrganic compound, such as sugars, starch and cellulose, that is made of carbon, hydrogen and oxygen. The hydrogen and oxygen are present in the same proportion as in water (2:1).
cellThe smallest structural and functional unit of which all living things are built.
cell theoryStates that all organisms are composed of cells (and their products), all cells come from pre-existing cells and the cell is the smallest living organisational unit.
cell wallWall outside the cell membrane in plant cells (cellulose), some protists, prokaryotes (murein) and fungi (chitin).
centrioleSmall cylindrical structure composed of micro-tubules; occurs in pairs and involved in separation of chromosomes in animal cells.
chloroplastGreen organelle containing chlorophyll, present in some plant cells, in which photosynthesis takes place. Composed of many folded layers of membrane.
concentration gradientDifference in concentration of a solute between one region and another, for example across a membrane.
cytoplasmAll the contents of a cell except the nucleus.
cytosolFluid component of cytoplasm in which organelles are located.
diffusionPassive movement of a solute from a region of higher concentration to a region of lower concentration.
endoplasmic reticulumLayers of intracellular membranes; links between membrane-bound organelles and the plasma membrane; may be rough endoplasmic reticulum (associated with ribosomes) or smooth endoplasmic reticulum (lacking in ribosomes).
eukaryoteOrganism composed of one or more cells that contain distinct membrane-bound nuclei and many organelles; includes protists, fungi, plants, and animals.
facilitated diffusionPassive diffusion through selective protein channels in membranes.
fluid mosaic modelIn relation to cell membranes- fluid because of the lateral movement of lipid molecules and mosaic because of the irregular location of proteins in the membrane.
Golgi apparatusAn organelle composed of a stack of smooth membranous cisternae (flatterned sac-like structures) in which proteins and polysaccharides are assembled and packaged in vesicles for export from the cell.
hydrophilicPolar ions and molecules that dissolve easily in water.
hydrophobicNon-polar molecules that are relatively insoluble in water; means water fearing.
inorganic compoundAll compounds are than organic compounds; for example, water, carbon dioxide, calcium carbonate.
lipid'Fatty' organic compound, including fats and oils, which is composed mainly of carbon, hydrogen, and oxygen. Lipids have proportionally less oxygen than carbohydrates, and may contain other elements.
lysosomeMembrane-bound vesicle, found in most animal cells, in which powerful enzymes break down debris and foreign microorganisms.
mitochondrionOrganelle in which aerobic cellular respiration occurs, composed of many layers of folded membrane.
nucleic acidThe genetic material of all organisms; molecule in which information is stored that determines features of an organism and controls cellular activities.
nucleusIn a eukaryotic cell, a large organelle containing chromosomes (which control cellular activities) surrounded by a double-layer nuclear membrane with numerous nuclear pores.
organelleSubcellular structure found in eukaryotic cells which are involved in specific functions of the cell.
organic compoundAny of the complex molecules containing carbon that occur in living organisms; for example proteins, carbohydrates, and lipids.
osmosisPassive diffusion of free water molecules across a partially permeable membrane from a solution in which there are more free water molecules (a dilute solutions) to a solution in which there are less fewer free water molecules.
pHA measure of acidity or alkalinity, measured on a scale of 0 (most acid) to 14 (most alkaline). One unit on a pH scale means a tenfold difference in acidity or alkalinity.
partially permeableA membrane that allows the molecules of a solvent to pass freely across, but prevents the free passage of at least some solute molecules.
phospholipidFat-like substance, usually based on glycerol; phospholipids are essential components of cell membranes; are involved in the uptake of fats and fatty acids from the products of digestion,
plasma membraneA microscopic membrane of lipids and proteins which forms the external boundary of the cytoplasm of a cell or encloses a vacuole, and regulates the passage of molecules in and out of the cytoplasm.
plastidLarge organelle with a double membrane found in plant cells. Involved in either storage or photosynthesis.
polymerLarge organic molecules, formed by joining together many smaller molecules.
prokaryoteAn organism with a simple cellular structure, lacking most organelles.
proteinFunctional molecule that is composed of one or more polypeptides, which are linear sequences of amino acids.
protein structureFour levels: primary- the linear sequence of amino acids. secondary- pleating or coiling of the polypeptide chain. tertiary- subsequent three dimensional folding of the polypeptide. quaternary- aggregation of more than one poly peptide.
ribosomeTiny organelle often attached to the endoplasmic reticulum; composed of protein and RNA; the site of protein synthesis.
tonoplastThe membrane surrounding the vacuole in plant cells; regulates uptake into the vacuole.
vacuoleMembrane-bound liquid-filled space within cells. Vacuoles in plant cells are usually large and are involved in storage and turgidity. In other cells, vacuoles may be involved in intracellular digestion and water balance.
vesicleMembrane-bound organelle often involved in transport within the cell.