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The Cell

The Cell. Chapter 2. Outline. Cell theory Eukaryotic cell Cell structure Cell function. Cytology. Study of structure and function of cell Identified by Robert Hooke, 1665 50-100 trillion!!! . Cell Theory. All known living things are made up of cells

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The Cell

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  1. The Cell Chapter 2

  2. Outline • Cell theory • Eukaryotic cell • Cell structure • Cell function

  3. Cytology • Study of structure and function of cell • Identified by Robert Hooke, 1665 • 50-100 trillion!!!

  4. Cell Theory • All known living things are made up of cells • The cell is the structural and functional unit of all living things • All cells come from pre-existing cells by division • Cells contain hereditary information which is passed from cell to cell during cell division • All energy flow (metabolism & biochemistry) of life occurs within cells

  5. Cell Categories • Sex cells • Cells specialized for sexual reproduction • Found only in the gonads • Created by meiosis • Somatic cells • All remaining cells in the body • Varied in structure & function • Created by mitosis

  6. Sex Cells Somatic Cells Cells exhibit patterns of form and function

  7. The Cell in a Nutshell

  8. Extracellular Matrix • The substance in which animal tissue cells are embedded • Matrix structure • Proteins • Polysaccharides • Support • Adhesion • Movement • Regulation

  9. Membrane Structure & Function • Plasma membrane • Phospholipid bilayer • Fluid Mosaic model • Selective permeability • Function • Physical isolation • Regulation of exchange with the environment • Sensory • Structural support

  10. Phospholipid Membrane

  11. Fluid Mosaic Model

  12. Membrane Proteins

  13. Cell Recognition

  14. Cytoskeleton • Infrastructure of cell • Maintains shape • Mechanical support • Organelle suspension • Movement • Cell division

  15. Cytoskeleton Elements • Microfilaments • Connect with cell proteins • Active movement • Ex muscles • Microtubules • Cell skeleton • Spindle fibers, cilia, flagella • Microvilli • Projections of cell surface • Increase surface area • Ex small intestine

  16. Microfilaments • http://dept.kent.edu/projects/cell/intro2.htm

  17. Cilia & Flagella Microtubule (9-2)

  18. Microvilli increase surface area

  19. Cytoplasm • Space inside the cell contains contents of the cell • Cytosol • Intracellular fluid • Contains • Dissolved nutrients & ions • Proteins & enzymes • Amino acids & lipids • Wastes & nutrients • Inclusions- stored nutrients • Glycogen granules • Lipid drops • Organelles

  20. Organelles • “little organs” • Specialized compartmentalized regions of cell • Perform specific functions • Vary according to cell function • Suspended in cytosol, anchored by cytoskeleton

  21. Nucleus • Nuclear envelope • Double membrane • Nuclear pores • Chromatin • (Chromosomes) • Nucleolus

  22. Chromatin vs Chromosomes

  23. Ribosomes • Produced in the nucleus by nucleolus • Active in cytoplasm • Cytosol- free • Endoplasmic reticulum- fixed • Site of protein synthesis

  24. Endomembrane System • Multi-organelle system • Functions in synthesis & distribution of cellular products • Endoplasmic reticulum • Smooth & rough • Golgi apparatus • Vacuoles

  25. Endoplasmic Reticulum • Tube & sac structure • Internal compartment • Smooth ER • Enzymes • Lipid synthesis • Detoxification • Rough ER • Ribosome • Membrane proteins • Secretory proteins

  26. Golgi Apparatus • Storage, modification, distribution • Enzymes & other proteins • Receive products from ER • “Address packages”

  27. Vacuoles aka Vessicles • Membranous sacs • Functionally variable • Derived from organelles • ER • Golgi • Plasma membrane • Diverse function • Movement/ Pumps • Transport vesicles • Intracellular Digestion • Lysosomes • Storage • Toxins • Food

  28. Lysosome • “Breakdown body” • Sacs of Digestive enzymes • Proteins • Polysaccharides • Fats • Nucleic acids • Damaged cells organelles

  29. Lysosomal Storage Diseases • Disease of missing lysosomal enzyme • Results in an inability to process molecules naturally • Results in the accumulation of the undigested molecule until they interfere with cell function • Ex. Tay-sachs disease • Missing enzyme that breaks down lipids in nerve cells • Impairs nerve function causes

  30. Mitochondria • Powerhouse of the cell • Conversion of chemical energy to cellular energy • Production of ATP via aerobic respiration

  31. Cell Function • Membrane Permeability • Ability of molecules to move in &/or out of a cell • Selectively permeable • Allows passage of some but not others • Size • Electrical charge • Molecular shape • Lipid solubility

  32. Membrane Transport • Passive transport • No direct energy investment required • Diffusion • Osmosis • Filtration • Facilitated diffusion • Active transport • Requires ATP

  33. Diffusion • Net movement of molecules from an area of high concentration to and area of low concentration • Driven by random movement • High concentration to low concentration • “down a concentration gradient” • Dynamic equilibrium • The tendency for molecules to spread out evenly in an available space • Net movement

  34. Diffusion can occur across a membrane

  35. Osmosis • Passive transport of a solute (water) across a selectively permeable membrane • Pattern of net movement • Movement directed by solute concentrations & pressure

  36. Osmoregulation

  37. Filtration • Movement of a fluid across a semi-permeable membrane • Driven by pressure

  38. Facilitated Diffusion • Passive diffusion across a selectively permeable membrane with the assistance of a carrier membrane protein • Requires NO ATP

  39. Active Transport • Requires cellular energy (ATP) • Works against concentration gradient • Endocytosis • Phagocytosis • Pinocytosis • Exocytosis

  40. Endocytosis & Exocytosis Possible because of the fluid nature of the plasma membrane

  41. Cell Division • Duplication & division separate stages • Interphase • Mitosis & cytokinesis • 2 types of division • Mitosis • Meiosis • Differential rates

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