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Chapter 6 Vocab

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cell theory
idea that all living things are composed of cells, cells are the basic units of structure and function in living things, and new cells are produced from existing cells
micrograph
photograph of the view through a microscope
organelle
part of a cell with a specific job to do
plasma membrane
defines the boundary of the cell and regulates the traffic of chemicals between the cell and its surroundings
nucleus
houses the cell's genetic material in the form of DNA
cytoplasm
consists of various organelles suspended in a fluid
cell wall
protects the plant cell and maintains its shape
prokaryotic cell
cell lacking a nucleus and most other organelles
eukaryotic cell
cell with a nucleus surrounded by its own membrane and other internal organelles
phospholipid bilayer
two-layer "sandwich" of molecules that surrounds a cell
diffusion
the net movement of the particles of a substance from where they are more concentrated to where they are less concentrated
equilibrium
balance
selectively permeable membrane
membrane that allows some substances to pass more easily than others and blocks the passage of some substances altogether
passive transport
transport of a substance across a cell membrane by diffusion
facilitated diffusion
transport proteins provide a pathway for certain molecules to pass
osmosis
the passive transport of water across a selectively permeable membrane
hypertonic
the solution with the higher concentration of solute
hypotonic
the solution with the lower solute concentration
isotonic
solutions in which the concentrations of solute are equal
active transport
when a cell expends energy to move molecules or ions across a membrane
vesicles
small membrane sacs that specialize in moving products into, out of, and within a cell
exocytosis
process by which vesicles release their contents outside the cell
endocytosis
process by which a cell takes material into the cell within vesicles that bud inward from the plasma membrane
nuclear envelope
surrounds the nucleus
nucleolus
contains the parts that make up organelles called ribosomes
ribosomes
clusters of proteins and nucleic acids assembled from components made in the nucleolus
endoplasmic reticulum
within the cytoplasm of a cell, an extensive network of membranes
golgi apparatus
an organelle that modifies, stores, and routes proteins and other chemical products to their next destinations
vacuoles
large membrane-bound sacs
lysosomes
membrane-bound sacs that contain digestive enzymes that can break down macromolecules
chloroplasts
photosynthetic organelles found in some cells of plants and algae
mitochondria
site where cellular respiration occurs
ATP
the main energy source that cells use for most of their work