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(biology) the basic structural and functional unit of all organisms

Cell Theory

This says that all living things are made of cells, that cells are the basic unit of structure and function and that cells only come from other cells.


a part of the cell containing DNA and RNA and responsible for growth and reproduction


an organism with cells characteristic of all life forms except primitive microorganisms such as bacteria


a unicellular organism having cells lacking membrane-bound nuclei


A tiny cell structure that carries out a specific function within the cell


material between the cell membrane and the nucleus


the readily stainable substance of a cell nucleus consisting of DNA and RNA and various proteins

Nuclear Envelope

layer of two membranes that surrounds the nucleus of a cell


a threadlike body in the cell nucleus that carries the genes in a linear order


The organelle where ribosomes are made, synthesized and partially assembled, located in the nucleus


an organelle in the cytoplasm of a living cell

Endoplasmic Reticulum

a cell structure that forms a maze of passageways in which proteins and other materials are carried from one part of the cell to another

Golgi Apparatus

A system of membranes that modifies and packages proteins for export by the cell


an organelle found in the cytoplasm of most cells (especially in leukocytes and liver and kidney cells)


cell organelle that stores materials such as water, salts, proteins, and carbohydrates


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


organelle found in cells of plants and some other organisms that captures the energy from sunlight and converts it into chemical energy


a microscopic network of actin filaments and microtubules in the cytoplasm of many living cells that gives the cell shape and coherence


one of two small cylindrical cell organelles composes of 9 triplet microtubules

Cell Membrane

a thin membrane around the cytoplasm of a cell

Cell Wall

a thin membrane around the cytoplasm of a cell

Lipid Bilayer

double-layered sheet that forms the core of nearly all cell membranes

Concentration Gradient

Difference in concentration of a substance on two sides of a membrane


the movement of particles from regions of higher density to regions of lower density


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


of or involving muscular contraction in which tension is constant while length changes


(of a solution) having a higher osmotic pressure than a comparison solution


(of a solution) having a lower osmotic pressure than a comparison solution

Facilitated Diffusion

movement of specific molecules across cell membranes through protein channels

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 material into the cell by infolding of the cell membrane


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


process by which certain cells can engulf and incorporate droplets of fluid


the process by which a substance is released from the cell through a vesicle that transports the substance to the cell surface and then fuses with the membrane to let the substance out

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