Terminology

bacteria = a simple unicellular organism that lacks a nucleus and other organelles

biology = the study of living things

C

cell = the basic unit of life

cell cycle = the period of time from one cell division to the next

cell theory = the theory which states that all living things are made up of cells; that the cell is the functional unit of life; and that all cells come from pre-existing cells

cell membrane = the part of the cell that surrounds and holds the cell contents together; controls the movement of substances into and out of the cell

cell wall = a structure (made of cellulose) surrounding plant cells; supports and protects the cell

centriole = an organelle in many animal cells that is involved in the formation of spindle fibres (which split the chromosomes) during mitosis

chloroplast = organelle, found in green plants, that is the site of photosynthesis

chromosomes = contain the DNA (blueprints of genetic information) for the cell

cilia = small hair-like projections that help some unicellular organisms to move in liquid environments

coarse adjustment knob = a dial which makes large adjustments in focus and magnification compound light microscope

concentration gradient = the difference in concentration of a substance between two areas

cytokinesis = the process by which the cytoplasm divides to form two daughter cells cytoplasm

D

daughter cell = the new cells formed by the process of mitosis and cytokinesis

diffusion = the movement of particles from an area of high concentration to an area of low concentration

E

electron microscope = a type of microscope that projects electrons instead of light onto the specimen; electron microscopes can maginify much more that a light microscope; also, the images produced are three-dimensional and in black-and-white

endocytosis = the process by which a cell moves materials from outside the cell into its cytoplasm

exocytosis = the process by which a cell moves materials from inside its cytoplasm to the outside environment

eyepiece = also called the ocular lens, this is the part of the microscope one looks through; also magnifies the specimen by 10 times

F

field of view = the visible area of the specimen seen through the eyepiece of a compound microscope

fine adjustment knob = a dial which makes small adjustments in focus in magnification

flagella = tail-like structures that help propel unicellular organisms through liquid environments (singular is flagellum)

fungi = an organism, often unicellular, which obtains energy from dead or decaying matter

I

impermeable = allows nothing to pass through

iris diaphragm = a dial used to change the intensity of light which is shone on the specimen

L

lysosome = an organelle that breaks down food and digests waste

M

magnification = the degree to which the appearance of a specimen is enlarged (40, 100, or 400 times on our light microscopes)

mitochondria = creates energy for the cell; called the powerhouse (singular is mitochondrion)

mitosis = the process by which the nuclear contents of the cell (chromosomes) divide to form two identical copies of genetic material

multicellular organism = an organism that is made up of more than one cell

N

Nuclear membrane = the thin outer membrane that surrounds the nucleus

nucleus = the control centre (brain) in a cell; directs all cell activities and holds the chromosomes (genetic information)

O

objective lens = magnifies the object by 4x (low), 10x (medium), or 100x (high) depending on the setting

organ = two or more tissues working together to complete a similar task

organelle = a small structure found within a cell; performs a specific function in the cell

organism = a single, living thing

organ system = a group of organs working together to complete a similar task

osmosis = the diffusion of water across a selectively permeable (semi-permeable) membrane

P

phagocytosis = a type of endocytosis in which a cell uses pseudopods (a temporary projection of cells) to bring solid particles inside the cell from the external environment

photosynthesis = a process by which chlorophyll in chloroplasts uses the Sun's energy to convert carbon dioxide and water into sugar and oxygen

protist = an organism, often unicellular, which shares characteristics similar to animals and plants

R

revolving nosepiece = connected to the objective lenses; allows user to change magnification

S

stage = the platform which the slide (and specimen) is placed in order to view

stage clips = clips used to keep the slide in place when viewing

T

turgor pressure = the outward pressure that is exerted on the cell wall of a plant cell by the cell's contents when water is taken is via osmosis; the degree of the pressure is determined by the amount of water stored in the vacuole

U

unicellular organism = an organism made up of only one cell

V

vacuole = a membrane-surrounded organelle which stores food, water, and waste; it is larger in plant cells