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20 terms

Chapter 3 Biology = cells

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organelle
membrane-bound structure that is specialized to perform a distinct process within a cell
eukaryotic cell
cell that has a nucleus and other membrane-bound organelles
prokaryotic cell
a cell that does not have a nucleus or other membrane-bound organelles
mitochondrion
bean-shaped organelle that supplies energy to the cell and has its own ribosomes and DNA
chloroplast
organelle composed of numerous membranes that are used to convert solar energy into chemical energy; contains chlorophyll
nucleus
organelle composed of a double membrane that acts as the storehouse for most of the cell's DNA
vesicle
small organelle that contains and transports materials within the cytoplasm
vacuole
organelle that is used to store materials, such as water, food, or enzymes, that are needed by the cell
selective permeability
condition or quality of allowing some, but not all, materials to cross a barrier or membrane
passive transport
movement of molecules across the cell membrane without energy input from the cell
active transport
energy-requiring movement of molecules across a membrane from a region of lower concentration to a region of higher concentration (going against concentration gradient)
concentration gradient
difference in the concentration of a substance from one location to another
osmosis
diffusion of water molecules across a semipermeable membrane from an area of higher water concentration to an area of lower water concentration
diffusion
movement of dissolved molecules in a fluid or gas from a region of higher concentration to a region of lower concentration
hypertonic
solution that has a higher concentration of dissolved particles compared with another soution
hypotonic
solution that has a lower concentration of dissolved particles compared with another solution
facilitated diffusion
diffusion of molecules assisted by protein channels that pierce a cell membrane
endocytosis
uptake of liquids or large molecules into a cell by inward folding of the cell membrane
phagocytosis
uptake of a solid particle into a cell by engulfing the particle; see endocytosis
exocytosis
release of substances out of a cell by the fusion of a vesicle with the membrane