Transcript Ch. 4 Cells
Ch. 4 Cells Chapter 4 Cells There are 100 trillion cells in the human body A cell is a basic unit of life, and is the smallest of all organisms We need a microscope to see cells -Many contributions to the cell were made by: – – – – – – Robert Hook Robert Brown Mathias Schleiden Theodor Schwann Rudolf Virchow Anton van Leeuwenhoek- 1st microscope Cell Theory (3 parts) 1. all living things are composed of cells. 2. cells are basic unit of structure in living things 3. all cells come from pre-existing cells. Cell Structure • Cell Membrane is made up of lipids and proteins. – It is selectively permeable and made of 2 layers. (lipid bilayer) • Cell Wall (in plants) is around the outside and protects the cell. • Organelles: perform a specific function. – Nucleus: is the control center, or brain of cell • Prokaryotes are: cells with no nucleus • Eukaryotes are cells with a nucleus • Nuclear Envelope surrounds the nucleus • Nucleolus: in the nucleus. It produces ribosomes. • Chromatin is: strands of DNA and protein • Chromosomes are: densely packed, contain DNA and Protein for heredity. • -Cytoplasm is located: within the cell membrane. Contains all the minerals, gases, and organelles. • -Mitochondria: the power house of the cell. Provides energy to function. • -Chloroplasts: (plants) trap energy from sun for plant to use. • -Ribosomes: The site of protein synthesis • Endoplasmic Reticulum (ER): passageway for transport of materials – Smooth ER: synthesizes and regulates – Rough ER: prepares proteins for export • Golgi Apparatus: the post office. Prepares, and packs for secretion. Also Carb. Synthesis • Lysosomes: Clean up crew. Has enzymes to digest. • -Vacuoles: (plant) Storage of starch • -Plastids: (plant) store food and pigments • -Cilia: hair-like projection to sweep materials across and away from the cell • -Flagella: whip like tail for motility. • The level of Organization is: • Cells • Tissues • Organs • Organ Systems • Organism Cell Movement • -Passive Transport -Diffusion is: movement of molecules from greater concentration to lower conc. example: oxygen in alveoli to the blood Carbon dioxide in blood to the alveoli * Some examples of diffusion in the body are: -Equilibrium: -Hypotonic solution: solutions with salt conc. Lower than cell. -Hypertonic solution: conc. Higher than cells -Isotonic solution: conc. are equal. • Osmosis: diffusion of water through a selectively permeable membrane. example: small intestines and kidneys • Facilitated Diffusion: uses a carrier protein to move • Molecules move through membrane from higher to lower concentration, but need help to do so. • Example: The diffusion of glucose requires a Carrier Enzyme to bond to the glucose, making it soluble. • Active Transport: ATP used to move a substance from an area of lesser conc. To an area of greater conc. • Ex:-Sodium Potassium Pump • -Endocytosis: cells ingest fluid – Pinocytosis: When a stationary cell engulfs something. Ex: cells in kidneys – Phagocytosis: When a moving cell engulfs something. Ex: WBC in blood engulf bacteria • -Exocytosis: The release of materials out of the cell. • Filtration: – Water and dissolved materials are forced through a membrane from higher to lower pressure. – example: blood in tissues is forced through capillaries.