1. Robert J. Sullivan Marist College Suggested Lecture Presentation Copyright © 2009 Pearson Education, Inc. Chapter 3, Part A Structure and Function of Cells

2. Copyright © 2009 Pearson Education, Inc. Cells Are Classified by Internal Organization  Eukaryotes have  Plasma membrane  Nucleus: information center  Cytoplasm: fluid within membrane  Organelles: structures with specialized functions  Prokaryotes have  No nucleus  No true organelles

3. Copyright © 2009 Pearson Education, Inc. Cell Structure Reflects Cell Function  Muscle cells  Contain numerous organelles providing energy needed for muscle contraction  Nerve cells  Long and thin to carry impulses over distance  Small size is efficient

4. Copyright © 2009 Pearson Education, Inc. The Plasma Membrane Figure 3.5 Extracellular environment Carbohydrate groups Cholesterol Receptor protein Gated channel protein (closed position) Channel protein (always open) Cytoplasm Cytoskeleton filaments PhospholipidLipid bilayer GlycoproteinTransport protein

5. Copyright © 2009 Pearson Education, Inc. Structural Features of the Plasma Membrane  Lipid bilayer  Phospholipids: polar head and nonpolar tail  Cholesterol: makes membrane a bit more rigid  Proteins: provide means of transportation through membrane  Carbohydrates: recognition patterns for cells and organisms Animation—Membrane Structure PLAY

6. Copyright © 2009 Pearson Education, Inc. Diffusion: Passive Transport Through Membrane  Passive transport  No energy required  Diffusion  Movement from area of high concentration to low Figure 3.6

7. Copyright © 2009 Pearson Education, Inc. Osmosis: Diffusion of Water  Osmosis: net diffusion of water across a semipermeable membrane Figure 3.7

8. Copyright © 2009 Pearson Education, Inc. Diffusion and Osmosis Animation—Diffusion and Osmosis PLAY

9. Copyright © 2009 Pearson Education, Inc. Three Forms of Passive Transport  Passive transport is powered by the concentration gradient. In the cell it occurs as  Diffusion through lipid layer  Diffusion through protein channels  Facilitated transport  Transport or carrier proteins in the membrane assist in moving molecules across the membrane, down the concentration gradient, without expending energy

10. Copyright © 2009 Pearson Education, Inc. Active Transport  Active transport requires energy to move substances from an area of lower concentration to an area of higher concentration. Figure 3.9 Animation—Passive and Active Transport PLAY

11. Copyright © 2009 Pearson Education, Inc. Endocytosis and Exocytosis Move Materials in Bulk  Endocytosis moves material into cell  Exocytosis moves material out of cell Figure 3.10a–b Animation—Endocytosis and Exocytosis PLAY

12. Copyright © 2009 Pearson Education, Inc. Receptor Proteins in Active Transport  Receptor proteins  Span membrane  Receptor sites  Bind specific molecules Figure 3.11

13. Copyright © 2009 Pearson Education, Inc. Active Transport: The Sodium–Potassium Pump  Sodium–potassium pump expels unwanted ions, keeps needed ones, and maintains cell volume  ATP is used to expel three sodium ions for every two potassium ions brought into the cell  Increase cell volume = increase water in cytoplasm by decreasing pumping and allowing more sodium inside cell  Decrease cell volume = less water in cytoplasm by increasing pumping and expelling more sodium ions

14. Copyright © 2009 Pearson Education, Inc. Active Transport: The Sodium–Potassium Pump Figure 3.12a

15. Copyright © 2009 Pearson Education, Inc. Active Transport: The Sodium–Potassium Pump Figure 3.12b

16. Copyright © 2009 Pearson Education, Inc. Variations in Tonicity  Isotonic  Extracellular and intracellular ionic concentration equal  Hypotonic  Extracellular ionic concentration less than intracellular  Hypertonic  Extracellular ionic concentration more than intracellular

17. Copyright © 2009 Pearson Education, Inc. Tonicity Figure 3.13a

18. Copyright © 2009 Pearson Education, Inc. Internal Structures of an Animal Cell Figure 3.14 Nucleus Information center for the cell. Contains DNA Mitochondrion Produces energy for the cell Lysosome Digests damaged organelles and cellular debris Ribosomes Site of protein synthesis Secretory vesicle Membrane-bound shipping container Golgi apparatus Refines, packages, and ships macromolecular products Rough endoplas- mic reticulum Primary site of protein synthesis by ribosomes Smooth endoplas- mic reticulum Primary site of macromolecule synthesis other than proteins Cytoskeleton Structural framework of the cell Centrioles Microtubular structures involved in cell division Peroxisome Destroys cellular toxic waste Cytosol Semifluid gel material inside the cell Plasma membrane Controls movement of materials into and out of cell

19. Copyright © 2009 Pearson Education, Inc. Internal Structures of an Animal Cell Animation—Cell Structure PLAY