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Transcript
Structure and Function The cell is the smallest unit of life that can carry out all the functions of a living thing. History of the Discovery of Cells 1500’s: microscope (m.s.) invented by Dutch eyeglass makers (opticians) • 1665: Robert Hooke (English) saw empty “cells” or rooms when he observed cork under a m.s. Hooke’s drawing of cork as seen through his microscope. • 1674: Anton van Leeuwenhoek (Dutch) used hand-held m.s.’s to observe organisms and living cells in pond water and blood. A picture he drew using his microscope. What do you think it is? Fly eye! • 1820’s: Rene Dutrochet (French) concluded that various parts of organisms (liver, bone, etc.) are made of cells. • 1830’s: Robert Brown (Scottish) discovered the nucleus, or center of the cell. 1830’s: Felix Dujardin (French) discovered cytoplasm, or the clear, jelly-like material in the cell. • 1838: Matthias Schleiden (German) said that all plants and plant parts are made of cells. 1839: Theodor Schwann (German) said that all animals and animal parts are made of cells. (He later said ALL organisms are made of cells.) • 1858: Rudolf Virchow (German) said that all cells come from preexisting cells. 1970: Lynn Margulis Proposes the idea that organelles were once freeliving cells Cell theory developed by Schleiden, Schwann, and Virchow, consists of three principles: Cells are the basic units of all life. All organisms are made of one or more cells. All cells come from preexisting cells. Exceptions of Cell Theory: Where did first cell come from? (Remember Theory of Evolution explanation.) Virus particles have a protein coat and nucleic acid core. They have both living and nonliving characteristics and do not have all the parts of a complete cell. HIV Hepatitis C West Nile FLU SARS There are two basic types of living things: multicellular: organism made of many cells unicellular: organism made of one cell How cells vary: Shape is related to function. Nerve cells can be one meter long, but very thin. Mycoplasms: smallest cells cause respiratory diseases The largest is an unfertilized ostrich egg. Two types of cells eukaryotes: have a nucleus surrounded by a membrane (all cells except bacteria) prokaryotes: have no definite nucleus (bacteria) Pro = No: PROKARYOTIC CELLS HAVE NO NUCLEUS! Basic Cell Structures A cell must have three: cell membrane, nucleus, and cytoplasm. Cell Membrane thin layer of lipid (fats) and protein that controls what enters and leaves cell •made of phospholipids (glycerol, two fatty acids, and phosphate group) and protein molecules embedded in the lipid layer. •cell membranes are fluid (lipids and proteins are always in motion) forming “mosaics” (called fluid mosaic model) Cytoplasm material between the cell membrane and the nucleus • made of water and organic compounds organelles (cell parts) “float” in it • contains cytoskeleton: network of fibers and tubes extending throughout cytoplasm that gives support and helps anchor organelles. It also helps cells change shape. Nucleus contains chromosomes: most of the cell’s genetic material. All organisms have a specific number. Contains nucleolus: makes ribosomes, which in turn help make proteins in the cell. surrounded by a nuclear envelope, or lipid bilayer. Ribosomes make proteins from amino acids. They float in cytoplasm or are bound to membranes. Made by the nucleolus. Endoplasmic reticulum (ER) - network of membranes that produce and TRANSPORT materials for the cell. smooth ER has NO rough ER has ribosomes on it ribosomes on its surface - It makes lipids, processes - It helps in making carbohydrates, and protein secreted by the modifies chemicals that cell and new cell are toxic to the cell. membranes. Golgi apparatus (also called Golgi complex or Golgi bodies): flat, membranebound sacs where chemicals are sorted, packaged, and transported to other places. Mitochondria the “powerhouse” of the cell - Changes food compounds into a usable form of energy (ATP: adenosine triphosphate) for the cell Lysosomes sacs that have digestive enzymes to break down large molecules of carbs, proteins, lipids, and old organelles no longer useful. Vacuole membrane-bound organelle used for storage. There is a large, central one in plant cells (helps to maintain their shape) There are many small ones in animals. Types of Movement cilia: tiny, hair-like particles (ex. paramecium) flagella: large, whip-like tail (ex. human sperm) Cell Diversity 1. Plant Cells • have a cell wall, a tough, rigid outer covering that protects the cell and helps maintain its shape. • Cell walls are also found in fungi, algae, and bacteria • chloroplasts help make sugars during photosynthesis. • They also contain chlorophyll, the green pigment in plants. large central vacuole 2. Animal Cells have cytoskeleton but no cell wall for support do NOT contain chloroplasts may have many very small vacuoles Cells and Their Environment - semipermeable membrane lets certain molecules pass through and keeps others out. Cells have this! 1. Passive transport is the movement of a substance across a cell membrane WITHOUT the input of energy. NO ENERGY! 2. Osmosis is the diffusion of water molecules only. NO ENERGY! 3. Diffusion, the most common form of passive transport, is the movement of substances from areas of HIGH concentration to areas of LOW concentration. NO ENERGY! USES ENERGY (ATP)! 4. Active transport uses cellular energy to move substances across a cell membrane. molecules move from LOW concentration to HIGH concentration - helps organisms maintain homeostasis Bulk Movement used to transport large molecules across membrane Exocytosis takes materials OUT of the cell. Endocytosis carries materials INTO the cell. Pinocytosis (cell “drinking”) is when liquids are moved into the cell. Phagocytosis (cell “eating”) is when solids are moved into the cell. It’s how some organisms (ex. amoeba) get their food. Effect of Solution Concentrations Hypertonic: the concentration of solutes outside is higher than it is inside the cell. Isotonic: the concentration of solutes outside the cell is equal to that inside the cell. It should be the state of a normal cell. Hypotonic: the concentration of solutes outside is lower than it is inside the cell. 1. very hypotonic: the cell has burst due to the large amount of water entering it. Let’s take a quiz!! How many parts can you name? Now, Check your answers! Is this a plant or animal cell? 2. 3. 4. Plant Cell One large vacuole 2. 3. 4. Is this a plant or animal Cell? A. D. E. B. F. C. G. Animal Cell Let’s Check Your Answers! A. Nucleus B. Mitochondria C. Cell Membrane D. Smooth ER E. Golgi Body F. Rough ER G. Lysosome