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Cell specialization

the process in which cells develop in different ways to perform different tasks.


group of similar cells that perform a particular function.


group of tissues that work together to perform closely related functions.

Organ system

group of organs that work together to perform a specific function.

Cell membrain

thin, flexible barrier around a cell; regulates what enters and leaves the cell.

Cell wall

strong supporting layer around the cell membrane in plants, algae, and some bacteria.

Lipid bilayer

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


the mass of solute in a given volume of solution, or mass/volume.


process by which molecules tend to move from an area where they are more concentrated to an area where they are less concentrated.


when the concentration of a solute is the same throughtout a solution.


Diffusion of water through a selectively permeable membrane.


when the concentration of two solutions in the same.


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


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

Facillitated diffusion

movement of specific molecules across cell membranes through protein channels.

Active transport

energy-requiring process that moves material across a cell membrain against a concentration difference.


process by which a cell takes material into the cell by infolding of the cell membrane.


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


process by which a cell takes in liquid from the surrounding environment.


process by which a cell releases large amounts of material.


specialized structure that performs important cellular functions within a eukaryotic cell.


material inside the cell membrane - not including the nucleus.

Nuclear envelope

layer of two membranes that surround the nucleus of cell.


granular material visible within the nucleus; consists of DNA tightly coiled around proteins.


thread like structure within the nucleus containing the genetic information that is passed from one generation of cells to the next.


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

Endoplasmic reticulum

internal membrane system in cells in which lipid components of the cell membrane are assembled and some proteins are modified.

Golgi apparatus

stack of membrains in the cell that modifies, sorts, and packages proteins from the endoplasmic reticulum.


cell organelle filled with enzymes needed to break down certain materials in the cell.


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


cell organelle that converts the chemical energy stored in food into compounds that are more convenient for the cell to use.


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


network of protein filaments withing some cells that helps the cell maintain its shape and is involved in many forms of cell movement.


one of two tiny structures located in the cytoplasm of animal cells near the nuclear envelope.


collection of living matter enclosed by a barrier that separates the cell from its surroundings; basic unit of all forms of life.

Cell theory

idea that all living things are composed of cells, cells are the basic unites of structure and function in living things, and new cells are produced from existing cells.


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


organism whose cells contain nucleus.


unicellular organism lacking a nucleus.

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