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Biology Ch. 7
Term | Definition |
---|---|
Cell | Basic unit of all forms of life. |
Cell Theory | Fundamental concept of biology that states that all living things are composed of cells; that cells are the basic unit of structure and function in living things; and that new cells are produced from existing cells. |
Cell Membrane | Thin, flexible barrier that surrounds all cells; regulates what enters and leaves the cell. |
Nucleus | Structure that contains the cell's genetic material in the form of DNA. |
Eukaryote | Organism whose cells contain a nucleus. |
Prokaryote | Unicellular organism that lacks a nucleus. |
Cytoplasm | In eukaryotic cells, all cellular contents outside the nucleus; in prokaryotic cells, all the cells' contents. |
Organelle | Specialized structure that performs important cellular functions within a cell. |
Vaculoe | Cell organelle that stores materials such as water, salts, proteins, and carbohydrates. |
Lysosome | Cell organelle that breaks down lipids, carbohydrates, and proteins into small molecules that can be used by the rest of the cell. |
Cytoskeleton | Network of protein filaments in a eukaryotic cell that gives the cell its shape and internal organization and is involved in movement. |
Centriole | Structure in an animal cell that helps to organize cell division. |
Ribosome | Cell organelle consisting of RNA and protein found throughout the cytoplasm in a cell; the site of protein synthesis. |
Endoplasmic Reticulum | Internal membrane system found in eukaryotic cells; place where lipid components of the cell membrane are assembled. |
Golgi Apparatus | organelle in cells that modifies, sorts, and packages proteins and other materials from the endoplasmic reticulum for storage in the cell or release outside the cell. |
Chloroplast | Organelle found in cells of plants and some other organisms that captures energy from sunlight and converts it into chemical energy. |
Mitochondrion | Cell organelle that converts the chemical energy stored in food into compounds that are more convenient for the cell to use. |
Cell Wall | Strong, supporting layer around the cell membrane in some cells. |
Lipid Bilayer | Flexible double-layered sheet that make up the cell membrane and forms a barrier between the cell and its surroundings. |
Selective Permeable | Property of biological membranes that allow some substances to pass across it while others cannot; also called semipermeable membrane. |
Diffusion | Process by which particles tend to move from an area where they are more concentrated to an area where they are less concentrated. |
Facilitated diffusion | Process of diffusion in which molecules pass across the membrane through cell membrane channels. |
Aquaporin | Water channel protein in a cell. |
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. |
Osmotic Pressure | Pressure that must be applied to prevent osmotic movement across a selectively permeable membrane. |
Homeostasis | Relatively constant internal physical and chemical conditions that organisms maintain. |
Tissue | Group of similar cells that perform a particular function. |
Organ | Group of tissues that work together to perform closely related functions. |
Organ System | Group of organs that work together to perform a specific function. |
Receptor | on or in a cell. a specific protein to whose shape fits that of a specific molecular messenger, such as a hormone. |