Vocabulary From Chapter 4 Of Modern Biology By Holt Rinehart Winston

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cell

Back 1

in biology, the smallest unit that can perform all life processes; cells are covered by a membrane and contain DNA and cytoplasm

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cell theory

Back 2

the theory that states that all living things are made up of one or more cells, that cells are the basic units of organisms, that each cell in a multicellular organism has a specific job, and that cells come only from existing cells

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plasma membrane

Back 3

the cell's outer boundary

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cytoplasm

Back 4

the region of the cell within the membrane that includes the fluid, the cytoskeleton, and all of the organelles except the nucleus

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cytosol

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the soluble portion of the cytoplasm, which includes molecules and small particles, such as ribosomes, but not the organelles covered with membranes

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nucleus

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a membrane-bound organelle that contains the cell's DNA and that has a role in processes such as growth, metabolism, and reproduction

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prokaryote

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a single-celled organism that has no nucleus and has no membrane-bound organelles

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eukaryote

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an organism made up of cells that have a nucleus enclosed by a membrane,multiple chromosomes, and a mitotic cycle

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organelle

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one of the small bodies that are found in the cytoplasm of a cell and that are specialized to perform a special function

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tissue

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a collection of specialized cells and cell products that perform a specific function

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organ

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a collection of tissues that carry out a specialized function of a body

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lysosome

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a cell organelle that contains dgiestive enzymes and that buds from the Golgi apparatus

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phospholipid bilayer

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a double layer of phospholipids that makes up plasma and organelles

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chromosome

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one of the structures in the nucleus that are made up of DNA and protein

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nuclear envelope

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the double membrane that surrounds the nucleus of a eukaryotic cell

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nucleolus

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the part of the eukaryotic nucleus where ribosomal RNA is synthesized

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ribosome

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a cell organelle composed of RNA and protein

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mitochondrion

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the cell organelle that is surrounded by two membranes and that is the site of cellular respiration, which produces ATP

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endoplasmic reticulum

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a system of membranes that is found in a cell's cytoplasm and that assists in the production, processing, and transport of proteins and in the production of lipids

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Golgi apparatus

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a cell organelle that helps make and package materials to be transported out of the cells

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cytoskeleton

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the cytoplasmic network of protein filaments and tubes that plays an essential role in cell movement, shape, and division

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microtubule

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one of the small, tubular fibers composed of the protein tubulin that are fond in the cytoplasm of eukaryotic cells, that compose the cytoskeleton, and that play a role in cell structure and movement

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microfilament

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a fiber found inside eukaryotic cells that is composed mainly of the protein actin and that has a role in cell structure and movement

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cilium

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a hairlike structure arranged in tightly packed rows that projects from the surface of some cells

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flagellum

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a long, hairlike structure that grows out of a cell and enables the cell to move

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centriole

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an organelle that is composed of two short microtubules at right angles to each other and that has an active role in mitosis

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cell wall

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a rigid structure that surrounds the cell membrane and provides support to the cell

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central vacuole

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in some protists and in most plant cells, a large, fluid-filled organelle that stores water, enzymes, metabolic wastes, and other materials

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plastid

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an organelle of plant cells that contains specific substances and performs specific functions for the cell

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chloroplast

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an organelle found in plant and algae cells where photosynthesis occurs

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thylakoid

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a membrane system found within chloroplasts that contains the components for photosynthesis

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chlorophyll

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a green pigment that is present in most plant cells, that gives plants their characteristic green color, and that reacts with sunlight, carbon dioxide, and water to form carbohyrates