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cell

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

organelle

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

nucleus

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

microtubles

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

microfilaments

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

ribosome

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

multicellular

made of many cells

unicellular

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

lysosome

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

vacuole

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

mitochondria

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

nucleolus

organelle in eukaryotic cell nucleus that produces ribosomes

plastids

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

flagella

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

cilia

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

chloropast

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

centriole

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

cytoplasm

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

prokaryote

A unicellular organism that lacks a nucleus and membrane bound organelles

eukaryote

A cell that contains a nucleus and membrane bound organelles

diffusion

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

equilibrium

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

osmosis

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

hypertonic

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

hypotonic

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

isotonic

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

endocytosis

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

phagocytosis

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

exocytosis

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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