1 / 62

Chapter 4 Lecture Outline See PowerPoint Image Slides for all figures and tables pre-inserted into

Chapter 4 Lecture Outline See PowerPoint Image Slides for all figures and tables pre-inserted into PowerPoint without notes. The Cell Theory. All living things are made of cells. A cell The basic unit of all living things. The Historical Context of the Cell Theory.

abel-kemp
Download Presentation

Chapter 4 Lecture Outline See PowerPoint Image Slides for all figures and tables pre-inserted into

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Chapter 4 Lecture Outline See PowerPoint Image Slides for all figures and tables pre-inserted into PowerPoint without notes.

  2. The Cell Theory • All living things are made of cells. • A cell • The basic unit of all living things.

  3. The Historical Context of the Cell Theory • Robert Hooke coined the term “cell.” • Look at cork cells under a simple microscope. • Anton van Leeuwenhoek • Made better microscopes • Used them to look at a variety of substances and identified animalcules

  4. The Historical Context of the Cell Theory • Mathias Jakob Schleiden • Concluded that all plants were made of cells • Theodor Schwann • Concluded that all animals were made of cells

  5. Initial Observations of Cells • Cell wall • Outer non-living part of plant cells • Protoplasm • Interior living portion of the cell • Nucleus • Contains the genetic information of the cell • Cytoplasm • Fluid part of the protoplasm • Organelles • “Little organs” within the protoplasm

  6. Different Kinds of Cells • Prokaryotic • Structurally simple cells • Lack a nucleus • Lack most other organelles, lack membrane bound organelles • Bacteria • Eukaryotic cells • More complex • Have a nucleus • Have a variety of membrane bound organelles • Plants, animals, fungi, protozoa and algae • Typically much larger than prokaryotic cells

  7. Major Cell Types

  8. Cell Size • Prokaryotic cells • 1-2 micrometers in diameter • Eukaryotic cells • 10-200 micrometers in diameter

  9. Surface Area-to-Volume Ratio • Cell size is limited. • Cells must get all of their nutrients from their environment through their cell membranes. • Volume increases more quickly than surface area. • Surface area-to-volume ratio must remain small.

  10. The Structure of Cell Membranes • Cell membranes • Thin sheets composed of phospholipids and proteins • Fluid-mosaic model • Two layers of phospholipids • Fluid • Has an oily consistency • Things can move laterally within the bilayer. • Mosaic • Proteins embedded within the phospholipid bilayer

  11. The Phospholipid Bilayer • Phospholipid structure • Hydrophobic tails • Hydrophilic heads • Bilayer • Hydrophobic tails of each layer associate with each other. • Hydrophilic heads on the surface of the bilayer • Cholesterol • Hydrophobic • Found within the hydrophobic tails • Keeps the membrane flexible

  12. Membrane Proteins • Some are on the surface • Some are partially embedded. • Protrude from one side • Some are completely embedded. • Protrude from both sides • Functions • Transport molecules across the membrane • Attachment points for other cells • Identity tags for cells

  13. Voyage to the cell membrane • http://www.youtube.com/watch?v=GW0lqf4Fqpg&feature=related • http://www.youtube.com/watch?v=ULR79TiUj80

  14. Cells Alive • http://www.cellsalive.com/

  15. Organelles Composed of Membranes • Plasma membrane (cell membrane) • Different cellular membranous structures serve different functions • Endoplasmic reticulum • Golgi apparatus • Lysosomes • Peroxisomes • Vacuoles and vesicles • Nuclear membrane

  16. The Plasma Membrane • Composed of a phospholipid bilayer • Separates the contents of the cell from the external environment • Important features • Metabolic activities • Moving molecules across the membrane • Structurally different inside and outside • Identification: Self vs. nonself • Attachment sites • Signal transduction

  17. The Endoplasmic Reticulum • Consists of folded membranes and tubes throughout the cell • Provides a large surface area for important chemical reactions • Because it is folded, it fits into a small space. • Two types of ER • Rough • Has ribosomes on its surface • Sites of protein synthesis • Smooth • Lacks ribosomes • Metabolizes fats • Detoxifies damaging chemicals

  18. The Golgi Apparatus • Stacks of flattened membrane sacs • Functions • Modifies molecules that were made in other places • Manufactures some polysaccharides and lipids • Packages and ships molecules

  19. Traffic Through the Golgi • Vesicles bring molecules from the ER that contain proteins. • Vesicles fuse with the Golgi apparatus. • The Golgi finishes the molecules and ships them out in other vesicles. • Some are transported to other membrane structures. • Some are transported to the plasma membrane. • Some vesicles become lysosomes.

  20. Lysosomes • Vesicles containing enzymes that digest macromolecules • Carbohydrates • Proteins • Lipids • Nucleic acids • Interior contains low pH • These enzymes only work at pH=5. • The cytoplasm is pH=7. • If the lysosome breaks open, these enzymes will inactivate and will not damage the cell.

  21. Functions of Lysosomes • Digestion • Of food taken into the cell • Destruction • Disease-causing organisms • Old organelles

  22. Peroxisomes • Not formed from golgi membrane, but from ER membrane • Contain the enzyme catalase • Breaks down hydrogen peroxide • Breaks down long-chain fatty acids • Synthesizes cholesterol and bile salts • Synthesizes some lipids

  23. Vacuoles and Vesicles • Membrane-enclosed sacs • Vacuoles • Larger sacs • Contractile vacuoles found in many protozoa • Forcefully expel excess water from the cytoplasm • Vesicles • Smaller vesicles

  24. Vacuoles and Vesicles

  25. The Nuclear Membrane • Separates the genetic material from the rest of the cell • Filled with nucleoplasm • Composed of two bilayers • Contains holes called nuclear pore complexes • Allow large molecules like RNA to pass through the membrane into the cytoplasm

  26. The Endomembrane System ̶ Interconversion of Membranes • Membranes are converted from one membranous organelle to another.

  27. Energy Converting Organelles • Mitochondrion • A small bag with a large bag stuffed inside • Larger internal bag is folded into cristae • Cristae contain proteins for cellular respiration. • Releases the energy from food • Requires oxygen • Uses the energy to make ATP

  28. Energy Converting Organelles • Chloroplasts • Sac-like organelle • Contain chlorophyll • Perform photosynthesis • Uses the energy in light to make sugar • Contain folded membranes called thylakoids • Thylakoids stacked into grana • Thylakoids contain chlorophyll and other photosynthetic proteins. • Thylakoids surrounded by stroma

  29. Nonmembranous Organelles • Ribosomes • Cytoskeleton • Centrioles • Cilia flagella • Inclusions

  30. Ribosomes • Made of RNA and proteins • Composed of two subunits • Large • Small • Are the sites of protein production • Found in two places • Free floating in the cytoplasm • Attached to endoplasmic reticulum

  31. Cytoskeleton • Provides shape, support and movement • Made up of • Microtubules • Microfilaments (actin filaments) • Intermediate filaments

  32. Centrioles • Two sets of microtubules arranged at right angles to each other • Located in a region called the centrosome • Microtubule-organizing center near nucleus • Organize microtubules into spindles used in cell division

  33. Cilia and Flagella • Hair-like projections extending from the cell • Composed of microtubules covered by plasma membrane • Flagella • Long and few in number • Move with an undulating whip-like motion • Cilia • Small and numerous • Move back and forth like oars on a boat • 9 + 2 arrangement of microtubules • Cell can control their activity

  34. Cilia and Flagella

  35. Inclusions • Collections of miscellaneous materials • Can be called granules • Temporary sites for the storage of nutrients and waste

  36. Nuclear Components • Contains chromatin • DNA + proteins • Becomes condensed during cell division into chromosomes • Surrounded by double layer of membrane • Nuclear membrane contains pores to control transport of materials in and out of nucleus • Contains one or more nucleoli • Site of ribosome synthesis • Contains nucleoplasm • Water, nucleic acids, etc.

  37. Cell Parts / Empire State of Mind • http://www.youtube.com/watch?feature=iv&annotation_id=annotation_254682&v=jqUhWDp73bM

  38. Getting Through Membranes • Diffusion • Facilitated diffusion • Osmosis • Active transport • Endocytosis • Exocytosis

  39. Diffusion • Molecules are in constant, random motion. • Molecules move from where they are most concentrated to where they are less concentrated. • This is called diffusion. • Involves a concentration gradient (diffusion gradient) • No concentration gradient=dynamic equilibrium

  40. The Rate of Diffusion • Depends on • The size of the molecule • Smaller molecules diffuse faster. • The size of the concentration gradient • The greater the concentration difference, the faster the diffusion.

  41. Diffusion in Cells • Diffusion can only happen if there is no barrier to the movement of molecules. • Can only happen across a membrane if the membrane is permeable to the molecule • Membranes are semi-permeable; they only allow certain molecules through. • Membrane permeability depends on the molecules size, charge, and solubility.

  42. The Direction of Diffusion • Determined solely by the concentration gradient • Diffusion that does not require energy input is passive. • Example: • Oxygen diffusion

  43. Diffusion • http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_diffusion_works.html

  44. Osmosis • The diffusion of water through a selectively-permeable membrane • Occurs when there is a difference in water concentration on opposite sides of the membrane. • Water will move to the side where there is less water • Or more solute

  45. Osmosis • http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_osmosis_works.html

  46. Osmotic Influences on Cells

  47. What happens if rbc is placed in a beaker of solution that is • Isotonic? • Hypertonic? • Hypotonic? RBC

  48. Osmosis in Animal and Plant Cells

  49. *Facilitated Diffusion • Some molecules have to be carried across the membrane. • Accomplished by carrier proteins • Still involves diffusion • Follows a concentration gradient • Is passive transport

  50. Passive Transport animation • http://www.youtube.com/watch?v=JShwXBWGMyY&feature=fvsr

More Related