bio ch3 vocab.txt

  1. actin filament
    cytoskeletal filaments of eukaryotic cells composed of the protein actin; also refers to the thin filaments of muscle cells.
  2. active site
    region on the surface of an enzyme where the substrate binds and where the reaction occurs
  3. active transport
    use of a plasma membrane carrier protein and energy to move a substance into or out of a cell from lower to higher concentration
  4. aerobic
    requiring oxygen
  5. anaerobic
    growing or metabolizing in the absence of oxygen
  6. cell theory
    one of the major theories of biology; states that all organisms are made up of cells and cells come only from preexisting cells.
  7. cellular respiration
    metabolic reactions that use the energy primarily from carbohydrates but also from fatty acid or amino acid breakdown to produce ATP molecules
  8. centrosome
    central microtubule organizing center of cells. in animal cells, it contains centrioles.
  9. chromatin
    network of fine threads in the nucleus composed of DNA and proteins.
  10. chromosome
    chromatin condensed into a compact structure
  11. cilium
    short, hair-like projection from the plasma membrane, occurring usually in large numbers.
  12. citric acid cycle
    cycle of reactions in mitochondria that begins with citric acid; it breaks down an acetyl group as CO2, ATP, NADH, and FADH2 are given off; also called the Krebs cycle.
  13. coenzyme
    nonprotein organic molecule that aids the action of the enzyme to which it is loosely bound
  14. cytoplasm
    contents of a cell between the nucleus and the plasma membrane that contains the organelles
  15. cytoskeleton
    internal framework of the cell, consisting of microtubules, actin filaments, and intermediate filaments.
  16. diffusion
    movement of molecules or ions from a region of higher to lower concentration; it requires no energy and stops when the distribution is equal.
  17. electron transport chain
    passage of electrons along a series of membrane-bound carrier molecules from a higher to lower energy level; the energy released is used for the synthesis of ATP.
  18. endomembrane system
    a collection of membranous structures involved in transport within the cell
  19. endoplasmic reticulum (ER)
    system of membranous saccules and channels in the cytoplasm, often with attached ribosomes.
  20. eukaryotic cell
    type of cell that has a membrane-bound nucleus and membranous organelles
  21. facilitated transport
    use of a plasma membrane carrier to move a substance into or out of a cell from higher to lower concentration; no energy required.
  22. fermentation
    anaerobic breakdown of glucose that results in a gain of two ATP and end products such as alcohol and lactate.
  23. flagellum
    slender, long extension that propels a cell through a fluid medium
  24. fluid-mosaic model
    model for the plasma membrane based on the changing location and pattern of protein molecules in a fluid phospholipid bilayer
  25. glycolysis
    anaerobic breakdown of glucose that results in a gain of two ATP molecules
  26. golgi apparatus
    organelle, consisting of saccules and vesicles, that processes, packages, and distributes molecules about or from the cell
  27. intermediate filament
    rope-like assemblies of fibrous polypeptides in the cytoskeleton that provide support and strength to cells; so called because they are intermediate in size between actin filaments and microtubules.
  28. lysosome
    membrane-bound vesicle that contains hydrolytic enzymes for digesting macromolecules
  29. metabolism
    all of the chemical reactions that occur in a cell
  30. microtubule
    small cylindrical structure that contains 13 rows of the protein tubulin around an empty central core; present in the cytoplasm, centrioles, cilia, and flagella.
  31. mitochondrion
    membrane-bound organelle in which ATP molecules are produced during the process of cellular respiration
  32. NAD+ (nicotinamide adenine dinucleotide)
    coenzyme that functions as a carrier of electrons and hydrogen ions, especially in cellular respiration.
  33. nuclear envelope
    double membrane that surrounds the nucleus and is connected to the endoplasmic reticulum; has pores that allow substances to pass between the nucleus and the cytoplasm.
  34. nuclear pore
    opening in the nuclear envelope that permits the passage of proteins into the nucleus and ribosomal subunits out of the nucleus
  35. nucleolus
    dark-staining, spherical body in the cell nucleus that produces ribosomal subunits.
  36. nucleoplasm
    semifluid medium of the nucleus, containing chromatin
  37. nucleus
    membrane-bounded organelle that contains chromosomes and controls the structure and function of the cell
  38. organelle
    small membranous structure in the cytoplasm having a specific structure and function
  39. osmosis
    diffusion of water through a selectively permeable membrane
  40. osmotic pressure
    measure of the tendency of water to move across a selectively permeable membrane; visible as an increase in liquid on the side of the membrane with higher solute concentration
  41. phagocytosis
    process by which amoeboid-type cells engulf large substances, forming an intracellular vacuole
  42. plasma membrane
    membrane surrounding the cytoplasm that consists of a phospholipid bilayer with embedded proteins; functions to regulate the entrance and exit of molecules from the cell
  43. polyribosome
    string of ribosomes simultaneously translating regions of the same mRNA strand during protein synthesis
  44. product
    substance that forms as a result of a reaction
  45. prokaryotic cell
    type of cell that lacks a membrane-bounded nucleus and organelles
  46. reactant
    substance that participates in a reaction
  47. ribosome
    RNA and protein in two subunits; site of protein synthesis in the cytoplasm
  48. selectively permeable
    having degrees of permeability; the cell is impermeable to some substances and allows others to pass through at varying rates.
  49. substrate
    reactant in a reaction controlled by an enzyme
  50. tonicity
    osmolarity of a solution compared with that of a cell. if the solution is isotonic to the cell, there is no net movement of water; if the solution is hypotonic, the cell gains water; and if the solution is hypertonic, the cell loses water
  51. vesicle
    small, membrane-bounded sac that stores substances within a cell
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bio ch3 vocab.txt