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Cell Structure and Function

Cell Structure and Function. Chapter 4. Cell Theory. 1) Every organism is composed of one or more cells 2) Cell is smallest unit having properties of life 3) Continuity of life arises from growth and division of single cells. Structure of Cells. All start out life with: Plasma membrane

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Cell Structure and Function

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  1. Cell Structure and Function Chapter 4

  2. Cell Theory 1) Every organism is composed of one or more cells 2) Cell is smallest unit having properties of life 3) Continuity of life arises from growth and division of single cells

  3. Structure of Cells All start out life with: • Plasma membrane • Region where DNA is stored • Cytoplasm • Two types: • Prokaryotic • Eukaryotic • Know table 4.2

  4. Animal Cell Features • Plasma membrane • Nucleus • Ribosomes • Endoplasmic reticulum • Golgi body • Vesicles • Mitochondria • Cytoskeleton

  5. nuclear enevelope nucleolus NUCLEUS DNA + nucleoplasm vesicle microfilaments components of cytoskeleton lysosome microtubules rough ER ribosomes (attached to rough ER and free in cytoplasm) smooth ER plasma membrane vesicle Golgi body pair of centrioles mitochondrion Fig. 4.8b, p. 57

  6. Lipid Bilayer • Main component of cell membranes • Gives the membrane its fluid properties • Two layers of phospholipids

  7. Bacteria Cells are unable to endocytose

  8. Membrane Proteins • Transport proteins • Receptor proteins • Recognition proteins • Adhesion proteins

  9. oligosaccharide groups cholesterol phospholipid EXTRACELLULAR ENVIRONMENT (cytoskeletal pro-teins beneatch the plasma membrane) open channel protein gated channel proten (open) gated channel proten (closed) active transport protein RECEPTOR PROTEIN LIPID BILAYER ADHESION PROTEIN RECOGNITION PROTEIN (area of enlargment) TRANSPORT PROTEINS CYTOPLASM PLASMA MEMBRANE Fig. 4.4, p. 53

  10. Functions of Nucleus • Keeps the DNA molecules of eukaryotic cells separated from metabolic machinery of cytoplasm • Makes it easier to organize DNA and to copy it before parent cells divide into daughter cells

  11. Components of Nucleus Nuclear envelope Nucleoplasm Nucleolus Chromosome Chromatin

  12. Nuclear Envelope • Two outer membranes (lipid bilayers) • Innermost surface has DNA attachment sites • Pores span bilayer

  13. Nucleolus • Dense mass of material in nucleus • May be one or more • Cluster of DNA and proteins • Materials from which ribosomal subunits are built • Subunits must pass through nuclear pores to reach cytoplasm

  14. Chromatin • Cell’s collection of DNA and associated proteins • Chromosome is one DNA molecule and its associated proteins • Appearance changes as cell divides

  15. Components of Cytomembrane System Endoplasmic reticulum Golgi bodies Vesicles

  16. Endoplasmic Reticulum • In animal cells, continuous with nuclear membrane • Extends throughout cytoplasm • Two regions - rough and smooth Ribosome Cisterns

  17. Rough ER • Ribosomes on surface give it a rough appearance • Some polypeptide chains enter rough ER and are folded and modified • Cells that specialize in secreting proteins have lots of rough ER

  18. Smooth ER • No ribosomes on surface • Lipids assembled inside tubules • Synthesizes steroids, such as estrogen and testosterone. • inactivates wastes, toxic chemicals and drugs

  19. Golgi Bodies • Put finishing touches on proteins and lipids that arrive from ER • Package finished material for shipment to final destinations outside the cell. • Material arrives and leaves in vesicles

  20. Vesicles • Membranous sacs that move through the cytoplasm • Lysosomes • Peroxisomes

  21. Mitochondria • ATP-producing powerhouses • Double-membrane system • Carry out the most efficient energy-releasing reactions • These reactions require oxygen

  22. Cytoskeleton • Present in all eukaryotic cells • Basis for cell shape and internal organization • Allows organelle movement within cells and, in some cases, cell motility

  23. Cytoskeletal Elements intermediate filament microtubule microfilament

  24. Mechanisms of Movement • Length of microtubules or microfilaments can change • Parallel rows of microtubules or microfilaments actively slide in a specific direction • Microtubules or microfilaments can shunt organelles to different parts of cell

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