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Chapter 7 vocab
A View of the Cell
| Term | Definition |
|---|---|
| cell | basic unit of all organisms; all living things are composed of cells |
| cell theory | the theory that (1) all organisms are composed of one or more cells, (2) the cell is the basic unit of structure and organization of organisms, (3) all cells come from preexisting cells |
| compound light microscope | instrument that uses light and a series of lenses to magnify objects in steps; can magnify an object up to 1500 times its original size |
| electron microscope | instrument that uses a beam of electrons instead of light to magnify structures up to 500,000 times actual size; allows scientists to view structures within a cell |
| eukaryote | unicellular or multicellular organisms, such as yeast, plants, and animals, composed of eukaryotic cells, which contain a true nucleus and membrane- bound organelles |
| nucleus | positively charged center of an atom composed of neutrons and positively charged protons, and surrounded by negatively charged electrons in eukaryotic cells, the central membrane-bound organelle that manages cellular functions and contains DNA |
| organelle | membrane-bound structures with particular functions within eukaryotic cells |
| prokaryote | unicellular organisms, such as bacteria, each of which is composed of a prokaryotic cell. Prokaryotic cells lack internal membrane-bound structures |
| fluid mosaic model | structural model of the plasma membrane where molecules are free to move sideways within a lipid bilayer |
| phospholipid | lipids with an attached phosphate group; plasma membranes are composed of phospholipid bilayer with embedded proteins |
| plasma membrane | flexible boundary between the cell and its environment; allows materials such as water and nutrients to enter and waste products to leave |
| selective permeability | feature of the plasma membrane that maintains homeostasis within a cell by allowing some molecules into the cell while keeping others out |
| transport proteins | proteins that span the plasma membrane creating a selectively permeable membrane that regulates which molecules enter and leave a cell |
| cell wall | fairly rigid structure located outside the plasma membrane of plants, fungi, most bacteria, and some protists; provides support and protection |
| chlorophyll | light absorbing pigment in plants and some protists that is required for photosynthesis; absorbs most wavelengths of light except for green |
| chloroplast | chlorophyll- containing organelles found in the cell of green plants and some protists; capture light energy and converted it to chemical energy |
| chromatin | long strands of DNA found in the eukaryotic cell nucleus; condense to form chromosomes |
| cilia | short, numerous, hairlike projections composed of pairs of microtubules; frequently aid in locomotion |
| cytoskeleton | cellular framework found within the cytoplasm composed of microtubules and microfilaments |
| endoplasmic reticulum | organelle in eukaryotic cells with a series of highly folded membranes surrounded in cytoplasm; site of cellular chemical reactions; can either be rough ( with ribosomes) or smooth ( without ribosomes) |
| flagella | long projections composed microtubules; found on some cell surfaces; they help propel cells and organisms by a whiplike motion |
| Golgi apparatus | organelle in eukaryotic cells with a system of flattened tubular membranes; sorts and packs proteins and sends them to their appropriate destinations |
| lysosome | organelles that contain digestive enzymes; digest excess or worn out organelles, food particles, and engulfed viruses or bacteria |
| microfilament | thin, solid protein fibers that provide structural support for eukaryotic cells |
| microtubule | thin, hollow cylinders made of proteins that provide structural support for eukaryotic cells |
| mitochondria | eukaryotic membrane-bound organelles that transform energy stored in food molecules; has a highly folded inner membrane that produces energy-storing molecules |
| nucleolus | organelle in eukaryotic cell nucleus that produces ribosomes |
| plastid | group of plant organelles that are used for storage of starches, lipids, or pigments |
| ribosome | nonmembrane-bound organelles in the nucleus where proteins are assembled |
| vacuole | membrane -bound space in the cytoplasm of cells used for the temporary storage of materials |