1. Cell - Structure & Function Unit #3

2. Generalized Cell Cellular level is where living processes occur. Disease processes occur at the cell level. Cancer cells

3. Cytology Or cellular biology, is the study of cellular structure and function. Ciliated columnar epithelial cells

4. Generalized Cell Cells are divided into three basic parts: Plasma (cell) membrane Cytosol (jelly-like fluid within the cell) Organelles Generalized Cell

5. Plasma membrane –Separates the cell’s internal environment from its external environment (interstitial fluid) –Composed of a lipid bilayer and proteins –Helps communication among cells Plasma membrane

6. Cytosol –All cellular contents between the nucleus and the plasma membrane is cytoplasm. –The thick semifluid of the cytoplasm is the cytosol. –75-90% water. Cell organelles & cytosol Tortora Pages 39-46

7. Generalized Cell OrganellesOrganelles –Highly organized structures with specific functions in the cell. Mitochondria Tortora Pages 39-40

8. Plasma Membrane Separates cell’s interior from the extracellular materials.Separates cell’s interior from the extracellular materials. Tortora Pages 39-40

9. Lipids Are Usually Triglycerides ContainsContains –Glycerol backbone –3 fatty acid chains. Can be SaturatedCan be Saturated –No double bonds –Straight –Solid at room Temp Can be unsaturatedCan be unsaturated –1 or more double bonds –Has bend –Less solid Tortora Pages 39-40 Glycerol “heads” are polar, fatty acids “tails” are non-polar.

10. How Do Phospholipids Differ? ContainsContains –Two layers of phospholipids –Phospholipids have; 2 fatty acid chains2 fatty acid chains 1 glycerol backbone1 glycerol backbone 1phosphorylated alcohol1phosphorylated alcohol –Tails are non polar and so hydrophobic –Heads are polar and so hydrophilic Tortora Pages 39-40

11. Plasma Membrane Bilayer of phospholipids Fatty acid tails point inward. –Away from ICF –Away from ECF Phospholipid heads orient towards ICF & ECF Fluid-like make up. Tortora Pages 39-40

12. Plasma Membrane Tortora Pages 39-40 ContainsContains –Integral Proteins. Through bilayerThrough bilayer –Peripheral proteins. Inside or outside surfaceInside or outside surface –Most of the proteins are glycoproteins –Cholesterol molecules

13. What Roles Do Proteins Play? Tortora Pages 39-40 Plays role in selective permeability –Ion channels –Transporters –Receptors –Enzymes –Cell identity markers –Anchors for cytoskeleton –Cell to Cell connection

14. How Do Viruses Use Surface Proteins? HIV recognizes CD4 (part of T lymphocytes) protein on cell surface. Gains entry & creates DNA molecule. DNA becomes part of cell’s DNA. Makes more viruses. Glycoprotein

15. Plasma Membrane Function Plasma membrane Passage of water Passage of bulk material Selective transport of molecules. Reception of information. Expression of cell identity. Physical connection with other cells

16. Movement of Materials Across Plasma Membrane Plasma membrane Intracellular fluid (ICF) is found inside of the cell. –Cytosol Extracellular fluid (ECF) is found outside of the cell. –Interstital fluid –Plasma –Lymph fluidTortora Pages 41-44

17. Passive Movement Across Plasma Membrane Plasma membrane Passive processes. –No use of cells energy. –Kinetic energy causes movement of substances across membrane. –Moves down the concentration gradient. –Eventually reaches dynamic equilibrium.Tortora Pages 41-44

18. Passive Movement cont’d Plasma membrane Simple diffusion. Net movement of molecules or ions from high concentration area to low concentration area. –O2 –CO2 –ions –small molecules –Polar moleculesTortora Pages 41-44

19. Movement of Materials: Facilitated Diffusion –Diffusion occurs with a “helper” molecule. –Helper molecule is a transmembrane protein. –Large molecules such as glucose. –Lipid soluble molecules.Tortora Pages 41-44

20. Example: –Glucose attaches to transporter protein on outside of cell. –Transporter changes shape. –Glucose passes through the membrane and is released inside of cell.Tortora Pages 41-44 Facilitated diffusion: glucose

21. Plasma membrane OsmosisOsmosis –Net movement of water from area of high concentration to area of low concentration through a selectively permeable membrane. –Water wanting to move down the concentration gradient causes osmotic pressure. –Osmotic pressure is the force required to stop the movement of water. Tortora Pages 41-44 Osmosis

22. Active Processes: use ATPTortora Pages 45-46 Cells use ATP (Cellular energy) to transport materials. Materials move from low to high concentration areas. (Up the conc. gradient) Integral proteins are needed to transport the material. Ex. Sodium/potassium pump.

25. Endocytosis Vs Exocytosis Tortora Pages 45-46 Endocytosis Cells moving large objects or molecules through the plasma membrane.Cells moving large objects or molecules through the plasma membrane. –Endocytosis - move materials into cell. –Exocytosis - move materials out of cells. –Plasma membrane forms a pseudopod. –Results in a phagocytic vesicle.

26. Phagocytosis Vs Pinocytosis Phagocytosis ‘Cell eating” Pinocytosis “Cell drinking”

27. Exibit 3.2 Quiz 1)Contains the genes of the cell. 2)Involved in the synthesis of lipids, proteins, and detoxifies some compounds. 3)Acts as a digestive structure. 4)Provides shape and support for the cell. 5)Moves materials across the surface of cells. 6)Provides movement of the whole cell. 7)Packages and delivers proteins for the cell. 8)Provides a location for ribosomes. 9)Builds proteins. 10)Regulates entrance of molecules into the cell and the exit of molecules from the cell.

28. Exibit 3.2 Quiz 1)Nucleus 2)Endoplasmic reticulum 3)Lysosome 4)Cytoskeleton 5)Cilia 6)Flagella 7)Golgi Apparatus 8)Rough ER 9)Ribosomes 10)Plasma membrane