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Chapters 7-8 Slide 2 Chapter 7 Slide 3 Discovery of cells light microscopes Anton van Leeuwenhoek 1 st light microscope Simple 1 lens, natural light First living unicellular organism pond water Compound light microscope series of lenses Greater magnification Slide 4 Discovery cont. Robert Hooke studies cork Cells monks rooms Matthias Schleiden all plants are made of cells Theodore Schwann all animals are made of cells Rudolph Virchow cells arise from other cells Slide 5 Statements of cell theory 1. All organisms are made of one or more cells and their products 2. The cell is the basic unit of structure of organisms 3. All cells come from preexisting cells Slide 6 Exceptions to cell theory The first cell Simple organisms lack separations that divide their bodies into cells Fungi and algae Viruses Mitochondria and chloroplasts divide on their own Slide 7 Electron microscopes No light beam of electrons Magnifies up to 500,000 X Slide 8 Scanning electron microscope (SEM) Scans surface of objects 3-D image Slide 9 Transmission electron microscope (TEM) Can see internal structures Slide 10 Scanning tunneling microscope (STM) Atoms on surface Slide 11 Slide 12 Prokaryotes Simple Lack internal structure No membrane- bound organelles Smallest organisms bacteria Slide 13 Eukaryotes More complex Definite internal structure Presence of membrane- bound organelles Slide 14 Slide 15 Maintains balance between internal and external conditions Regulates entering and departing substances Maintains cellular homeostasis Slide 16 Selectively permeable Also known as semipermeable Allows only certain molecules in or out Water may move freely Ions allowed in only at certain times Slide 17 Structure of the plasma membrane Phospholipid bilayer Lipids with phosphate groups (replace 1 fatty acid) Fatty acid tails nonpolar avoid water Water insoluble dissolved substances cant easily pass through Inner portion of membrane Slide 18 Structure cont. Phosphate heads polar attracted to water Cell can interact with watery environment Edges of membrane Cholesterol stabilizes phospholipids Prevents fatty acids from sticking together Transport proteins span membrane Act as channels (doors) through membrane Slide 19 Structure cont. Protein and carb identity markers Extend from outer surface for communication Proteins along inner surface attach membrane to internal support structures Fluid mosaic model phospholipids move within the membrane Provides flexibility Slide 20 Slide 21 Slide 22 Cellular boundaries All cells have plasma membranes Some also have cell walls Rigid structure outside the membrane providing extra support and protection Plant cells, fungi, some protists (unicellular) Fibrous made of cellulose Porous allows substances through arbitrarily Slide 23 Cellular boundaries cont. Nucleus control center Contains blueprints for making proteins chromatin (DNA) Separated from cell by porous nuclear envelope Nucleolus located within nucleus Site of ribosome production Slide 24 Cellular boundaries cont. Ribosomes protein synthesis Not membrane-bound Cytoplasm clear, gelatinous fluid inside cells Mostly water Site of cellular metabolism Slide 25 Assembly, transport, and storage Endoplasmic reticulum (ER) highly folded membrane in the cytoplasm Rough ER has ribosomes Protein synthesis and transport Smooth ER no ribosomes Lipid synthesis and transport Slide 26 Assembly cont. Golgi apparatus flattened system of tubular membranes Modify proteins and lipids Enclose finished products in vacuoles Vacuoles sacs surrounded by a membrane Temporary storage of food, enzymes, wastes, cell secretions Slide 27 Assembly cont. Lysosomes organelles containing digestive (hydrolytic) enzymes Digestion of excess or worn out organelles, food, engulfed viruses or bacteria Fuse with vacuoles to digest contents Can digest cells that made them Tadpole tails Fetal finger webbing Natural aging Slide 28 Energy transformers Chloroplasts plant cells & some protists Capture light energy to make food Surrounded by a double membrane Grana stacks of membranous sacs Contain chlorophyll light-capturing pigment Stroma fluid-filled spaces Slide 29 Slide 30 Energy transformers cont. Mitochondria all cells Transform carbs into energy Smooth outer membrane Highly folded inner membrane increased surface area for chemical reactions This is where energy molecules are produced Slide 31 Slide 32 Support and locomotion Cytoskeleton provides support, maintains shape Microtubules hollow tubes made of protein Microfilaments smaller, solid protein fibers Intermediate fibers mid-sized Slide 33 Support cont. Cilia and flagella Both composed of 9 pairs of microtubules surrounding a tenth pair Microtubules slide along each other bending Cilia short, numerous, wave-like motion Flagella long, 1 or 2, whip-like motion Slide 34 Cilia and flagella Paramecium Human spermatozoa Slide 35 Chapter 8 Slide 36 Osmosis Diffusion of water across a selectively permeable membrane Important in maintaining homeostasis Caused by concentration gradient of particles Slide 37 Isotonic solutions Concentration of solutes in solution = concentration of solutes inside cell Water moves in and out at the same rate No change in cell shape Slide 38 Hypotonic solutions Concentration of solutes in solution is lower than that inside the cell Water moves into cell cell bursts (plasmolysis) Slide 39 Hypertonic solutions Concentration of solutes in solution is higher than that inside the cell Water moves out of cell cell shrivels Wilting plants Slide 40 Slide 41 Passive transport Uses no energy Osmosis and diffusion Facilitated diffusion uses transport proteins Moving sugars and amino acids Slide 42 Active transport requires energy Uses carrier proteins Molecule binds to carrier protein Release of energy changes protein shape Molecule released on other side of membrane Protein returns to original shape Slide 43 Active transport cont. Endocytosis cell surrounds and take in particles Particle engulfed and enclosed by a membrane Membrane breaks away vacuole Exocytosis opposite of endocytosis http://www.coolschool.ca/lor/BI12/unit4/U04L05.htm Slide 44 Slide 45 Size limitations Diffusion is slow inefficient if cell is large It would take too long for nutrients to reach cell organelles DNA there must be enough to provide blueprints for sufficient amounts of protein Larger cells more than 1 nucleus Slide 46 Size limitations cont. Surface area-to-volume ratio Volume increases faster that surface area The higher the ratio, the more efficient diffusion will be Small cells have high ratios Slide 47 Slide 48 Cell reproduction chromosomes Chromatin long strands of DNA wrapped around proteins Chromosomes are in this form for most of a cells life During cell division, chromosomes become tightly coiled and visible under a microscope Slide 49 The cell cycle sequence of growth and division Most of the cycle is spent in growth Following growth, cells undergo nuclear division Mitosis process by which 2 daughter cells are formed, each identical to the original parent After mitosis, the entire cell divides Slide 50 Slide 51 Interphase 3 parts 1. Growth and protein synthesis G1 2. Cell copies chromosomes S 3. Mitochondria and other organelles replicate G2 Not considered a part of mitosis Slide 52 Slide 53 Prophase longest phase Chromatin coils into compact chromosomes Sister chromatids 2 halves of doubled structure Exact copies of each other Held together by a centromere Nuclear membrane and nucleolus disappear Slide 54 Prophase cont. Centrioles begin to migrate to opposite poles Organelles found only in animal cells Spindle fibers form between centrioles Slide 55 Slide 56 Metaphase Spindle fibers attach to centromeres Chromosomes line up along cell equator metaphase plate Slide 57 Slide 58 Anaphase Chromatids move to opposite poles pulled by shortening spindle fibers Slide 59 Slide 60 Telophase Chromatids reach opposite poles Reversal of prophase Slide 61 Slide 62 Cytokinesis Division of the cytoplasm Animal cells membrane pinches in at edges (cleavage furrow) Plant cells cell plate forms along equator from center of cell Slide 63 Differences in Cytokinesis Animal cell Plant cell Slide 64 Results of mitosis 2 new daughter cells identical to the original parent, but smaller Unicellular organisms remain as single cells Multicellular organisms organization Slide 65 Multicellular cellular organization Tissue group of cells performing a specific function Smooth muscle Organ combination of tissues performing a specific function Stomach Organ system combination of organs performing a specific function Nervous system Slide 66 Slide 67 Normal control enzymes Enzymes monitor cells progress from phase to phase Specific enzymes are used for each phase Enzymes encoded by genes on DNA Slide 68 Abnormal cell cycles cancer Cancer uncontrolled cell division Results from changes in genes encoding enzymes that control cell cycle Form masses of tissue tumors Deprive normal functioning cells of nutrients May metastasize spread through body #2 killer in USA Slide 69 Cancer cont. Causes: Genetic inherited Environmental cigarette smoke, air and water pollution, radiation, exposure to chemicals Viral infections Slide 70 Cancer cont. Prevention: Low fat, high fiber diets Vitamins and minerals Exercise Avoiding risk situations