cells
collection of living matter enclosed by a barrier that separates the cell from its surroundings; basic unit of all forms of life
cell theory
-All living things are composed of cells.
-Cells are the basic units of structure and function in living things.
-New cells are produced from existing cells.
nucleus
in cells, structure that contains the cell's genetic material (DNA) and controls the cell's activities
Eukaryote
organism whose cells contain nuclei. contains a nucleus in which their genetic material is separated from the rest of the cell.
Prokaryotes
unicellular organisms lacking a nucleus. have genetic material that is not contained in a nucleus.
organelles
specialized structure that performs important cellular functions within a eukaryotic cell
cytoplasm
material inside the cell membrane�not including the nucleus
nuclear envelope
layer of two membranes that surrounds the nucleus of a cell
chromatin
granular material visible within the nucleus; consists of DNA tightly coiled around proteins. consists of DNA bound to protein. is spread throughout the nucleus.
chromosomes
chromatin condenses to form this. threadlike structure within the nucleus containing the genetic information that is passed from one generation of cells to the next
nucleolus
where assembly of ribosomes begins. small, dense, region within most nuclei in which the assembly of proteins begins
ribosomes
small particle in the cell on which proteins are assembled; made of RNA and protein
endoplasmic reticulm (E.R.)
internal membrane system in cells in which lipid components of the cell membrane are assembled and some proteins are modified
golgi apparatus
stack of membrane in the cell that modifies, sort, and package proteins and other materials from the endoplasmic reticulum for storage in the cell or secretion outside the cell.
lysosomes
cell organelle filled with enzymes needed to break down certain materials in the cell
vacuoles
cell organelle that stores materials such as water, salts, proteins, and carbohydrates
mitochondria
cell organelle that converts the chemical energy stored in food into compounds that are more convenient for the cell to use. Nearly all eukaryotic cells &including plants contain this.
chloroplasts
found in plants & some other organisms. organelle found in cells of plants and some other organisms that captures the energy from sunlight and converts it into chemical energy
cytoskeleton
network of protein filaments within some cells that helps the cell maintain its shape and is involved in many forms of cell movement. Eukaryotic cells have this structure that helps support the cell.
centrioles
one of two tiny structures located in the cytoplasm of animal cells near the nuclear envelope.
cell membrane
thin, flexible barrier around a cell; regulates what enters and leaves the cell. All cells are surrounded by a thin, flexible barrier known as this.
cell wall
strong supporting layer around the cell membrane in plants, algae, and some bacteria. provide support and protection for the cell.
lipid bilayer
double-layered sheet that forms the core of nearly all cell membranes
concentration
the mass of solute in a given volume of solution, or mass/volume.
diffusion
process by which molecules tend to move from an area where they are more concentrated to an area where they are less concentrated
equilibrium
when the concentration of a solute is the same throughout a solution
osmosis
diffusion of water through a selectively permeable membrane
isotonic
when the concentration of two solutions is the same
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
facilitated diffusion
movement of specific molecules across cell membranes through protein channels
active transport
energy-requiring process that moves material across a cell membrane against a concentration difference.
endocytosis
process by which a cell takes material into the cell by infolding of the cell membrane
phagocytosis
process in which extensions of cytoplasm surround and engulf large particles and take them into the cell.
pinocytosis
process by which a cell takes in liquid from the surrounding environment
exocytosis
process by which a cell releases large amounts of material