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basic unit of all organisms; all living things are composed of cells

Cell Theory

the theory that (1) all organisms are composed of cells, (2) the cell is the basic unit of organization of organisms, (3) all cells come from preexisting cells


membrane-bound structures within eukaryotic cells

cell wall

firm, fairly rigid structure located outside the plasma membrane of plants, fungi, most bacteria, and some protists; provides support and protection


the center of the atom which contains the protons and neutrons; in cells, structure that contains the cell's genetic material (DNA) and controls the cell's activities


thin, hollow cylinders made of protein that provide structural support for eukaryotic cells


thin, solid protein fibers that provide structural support for eukaryotic cells


small particle in the cell on which proteins are assembled; made of RNA and protein


made of many cells


Made of a single cell

endoplasmic reticulum

organelle in eukaryotic cells with a series of highly folded membranes surrounded in cytoplasm; site of cellular chemical reactions; can either be rough (with ribosomes) or smooth (without ribosomes)

golgi apparatus

organelle in eukaryotic cells with a system of flattened tubular membranes; modifies proteins and sends them to their appropriate destinations


organelles that contain digestive enzymes; digest excess or worn out organelles, food particles, and engulfed viruses or bacteria


fluid filled space that stores water and nutrients for the cell; very large in plant cells


Powerhouse of the cell, organelle that is the site of ATP (energy) production.


organelle in eukaryotic cell nucleus that produces ribosomes


organelles that, like mitochondria, are surrounded by a double membrane and contain their own DNA.


long, thin, whip-like structures, with a core of microtubules, that enable some cells to move


short, numerous, hairlike projections composed of pairs of microtubles; frequently move in a wavelike motion; aid in feeding and locomotion


chlorophyll-containing cell organelles found in the cells of green plants and some protists; capture light energy from the sun, which is converted to chemical energy in food molecules


in animal cells, a pair of small cylindrical structures composed of microtubles that duplicate during interphase and move to opposite ends of the cell during prophase


clear, gelatinous fluid in eukaryotic cells that suspends the cell's organelles and is the site of numerous chemical reactions


A unicellular organism that lacks a nucleus and membrane bound organelles


A cell that contains a nucleus and membrane bound organelles


net, random movement of particles from an area of higher concentration to an area of lower concentration, eventually resulting in even distribution


the concentration of molecules will be the same throughout the space the molecules occupy


diffusion of molecules through a semipermeable membrane from a place of higher concentration to a place of lower concentration until the concentration on both sides is equal


when comparing two solutions, the solution with the greater concentration of solutes


when comparing two solutions, the solution with the lesser concentration of solutes


when the concentration of two solutions is the same

facilitated diffusion

pathway provided by transport proteins that helps certain molecules pass through a membrane

active transport

transport of a substance (as a protein or drug) across a cell membrane against the concentration gradient


process by which a cell takes in a substance by surrounding it with the cell membrane


process in which extensions of cytoplasm surround and engulf large particles and take them into the cell


active transport process by which materials are secreted or expelled from a cell

Symbiotic theory

?intimate association of apparently dissimilar organisms- comm. is comprised of many theories that all encompass the field?

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