<p>STUDY GUIDE – THE CELL</p><p>Cell Theory *1. All organisms composed of one or more cells. *2. Cell is smallest living organizational unit. *3. Cells arise only from division of other cells. </p><p>TYPES OF CELLS</p><p>Prokaryotic cells : simplest organisms: very small size (uni-cellular).  No nucleus. (They have DNA)  Strong cell walls and ribosomes  Lack membrane-bound organelles inside the cell.  Ex. Bacteria and viruses</p><p>Eukaryotic cells: complex cells: larger size (uni- and multi-cellular)  Central nucleus containing DNA  Membrane bound organelles (like ER, vacuoles, mitochondria, etc.)  Ex. Animals, plants, and fungi</p><p>ANIMAL CELL ORGANELLES Nucleus: Control center of cell. Cilia: Short hairs on cell membrane used for movement. Flagella: Long hairs on cell membrane used for movement. Cell Membrane: Thin covering of all cells. Controls what enters or leaves the cell. (semi-permeable for cell transport) Cytoplasm: The jelly-like liquid insides of a cell. Found between all cell organelles. Mitochondria: Powerhouse of cell. Chemically "burns" sugar to make energy for cell to use. (cellular respiration) Endoplasmic reticulum (ER): Tubes for transport and manufacture of large molecules. Rough ER: contains ribosomes for making proteins Smooth ER : Lack ribosomes so smooth surfaced tubes. Ribosomes: Place where cell proteins are made. Golgi Apparatus: Place where molecules are packaged into vesicles (for exocytosis). Vacuoles: Bubbles or "bags" for storage of food, water, chemicals, or wastes. Lysosomes: hold digestive enzymes. Help get rid of wastes or to digest cell food. </p><p>PLANT CELL ORGANELLES Cell Wall: Tough outer covering of all plant cells. Made of cellulose. Support, structure, and protection. Chloroplasts: Site of photosynthesis (Changes light energy into sugar energy). Contain green pigment chlorophyll Central Vacuole: Large storage site for water in plants. CELLULAR TRANSPORT</p><p>Homeostasis: maintaining a stable internal environment (equilibrium in the cell)</p><p>Cell membrane: semi-permeable lipid bi-layer studded with proteins for cell transport in and out</p><p>Passive transport: does not require energy . Moves DOWN a concentration gradient. High  Low</p><p> Diffusion: movement of molecules from an area of high to low concentration.</p><p> Osmosis: the movement of water molecules from high to low.</p><p>Hypertonic: higher inside than outside Water moves out of the cell (shrinks) Ex. Freshwater fish in saltwater or salt on a slug</p><p>Hypotonic: higher outside than inside Water moves into the cell (swells) Ex. Saltwater plant in freshwater</p><p>Isotonic: equal concentration inside and outside Equilibrium = no movement of water</p><p> Facilitated Diffusion: helper channel proteins in the cell membrane allow larger molecules through the membrane.</p><p>Active Transport: requires energy. Moves against (UP) a concentration gradient (low to high )</p><p> Protein pumps: proteins “pump” molecules from low to high using ATP.</p><p> Endocytosis: cell membrane surrounds molecules, forming a vesicle, and brings them INTO the cell.</p><p> Exocytosis: a vesicle containing large molecules makes an opening and squeezes the molecules OUT of the cell. </p>