Biology

• Cell


  The basic unit of structure and function in organisms (living things)

  
• Cell Theory


  The widely accepted theory 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
• Prokaryote


  Simple type of cell that lacks a nucleus and membrane-bound organelles

  
• Eukaryote


  A cell that contains a nucleus and membrane-bound organelles

  
• Cytoskeleton


  Network of protein filaments within some cells that helps the cell maintain its shape and is involved in many forms of cell movement

  
• Cytoplasm


  A jellylike fluid inside the cell in which the organelles are suspended

  
• Cytosol


  Fluid portion of cytoplasm

  
• Chloroplast


  An organelle found in plant and algae cells where photosynthesis occurs

  
• Vacuole


  Cell organelle that stores materials such as water, salts, proteins, and carbohydrates

  
• Cell wall


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

  
• Cellulose


  A substance (made of sugars) that is common in the cell walls of many organisms
• Nucleus


  An organelle of the cell containing DNA and RNA and responsible for growth and reproduction

  
• Nuclear envelope


  Double membrane perforated with pores that control the flow of materials in and out of the nucleus

  
• Deoxyribonucleic acid (DNA)


  A complex molecule containing the genetic information that makes up the chromosomes

  
• Nucleolus


  Found inside the nucleus and produces ribosomes

  
• Mitochondria


  An organelle found in large numbers in most cells, in which the biochemical processes of cellular respiration occur

  
• Ribosome


  Site of protein synthesis

  
• Endoplasmic Reticulum (ER)


  An extensive membranous network in eukaryotic cells, continuous with the outer nuclear membrane and composed of ribosome-studded (rough) and ribosome-free (smooth) regions.

  
• Rough Endoplasmic Reticulum


  An endomembrane system covered with ribosomes where many proteins for transport are assembled.

  
• Smooth Endoplasmic Reticulum


  An endomembrane system where lipids are synthesized, calcium levels are regulated, and toxic substances are broken down.

  
• Golgi apparatus


  A system of membranes that modifies and packages proteins for export by the cell

  
• Vesicle


  Small membrane-bound sac that functions in moving products into, out of, and within a cell

  
• Lysosome


  An organelle containing digestive enzymes

  
• Cilia


  Hairlike projections that extend from the plasma membrane and are used for locomotion

  
• Flagellum


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

  
• Surface area to volume ratio

  Ratio of a cell's outside surface area to its internal volume

  
• Plasma membrane


  A selectively-permeable phospholipid bilayer forming the boundary of the cells and controlling transport of substances into/out of a cell

  
• Semipermeable


  Membranes that allow some substances through but not others
• Phospholipids


  A molecule that is a constituent of the inner bilayer of biological membranes, having a polar, hydrophilic head and a nonpolar, hydrophobic tail

  
• Glycoproteins


  A protein in the membrane that is involved in intercellular communication

  
• Glycolipids


  Lipids with a carbohydrate attached, found in the cell membrane, and are involved in intercellular communication

  
• Fluid mosaic model


  Model that describes the arrangement and movement of the molecules that make up a cell membrane

  
• Diffusion


  The net movement of a substance from an area of higher concentration to an area of lower concentration, towards equilibrium (down the concentration gradient)

  
• Concentration gradient (diffusion)


  The direction of movement of a substance from higher concentration to lower concentration
• Osmosis


  Diffusion of water through a selectively permeable membrane from an area of lower solute concentration to an area of higher solute concentration

  
• Facilitated diffusion


  The transport of substances through a cell membrane along a concentration gradient with the aid of channel or carrier proteins

  
• Isotonic


  Describes a solution whose solute concentration is equal to the solute concentration inside a cell

  
• Hypotonic


  Describes a solution whose solute concentration is lower than the solute concentration inside a cell

  
• Hypertonic


  Describes a solution whose solute concentration is higher than the solute concentration inside a cell

  
• Carrier proteins


  Proteins that bind solutes and transport them across the plasma membrane