Cells

1. Carry out all chemical activities needed to sustain life • Cells are the building blocks of all living things • Cells must- metabolize, reproduce, respond, maintain boundaries, move, grow, digest foods, excrete wastes • Tissues are groups of cells that are similar in structure and function Cells

2. Surrounding cytoplasm of cell • Double phospholipid layer • Hydrophilic (polar) heads and hydrophobic (nonpolar) tails • Other materials in plasma membrane • Protein- transport across the membrane • Cholesterol- stability • Glycoproteins- cell recognition, hormone attachment, cell signaling • Barrier for cell contents, controls entrance/exit of materials Plasma Membrane

3. Plasma Membrane

4. Cellular Physiology: Membrane Transport • Membrane Transport – movement of substance into and out of the cell • Transport is by two basic methods • Passive transport • No energy is required • Active transport • The cell must provide metabolic energy

5. Solution – homogeneous mixture of two or more components • Solvent – dissolving medium • Solutes – components in smaller quantities within a solution • Intracellular fluid – nucleoplasm and cytosol • Interstitial fluid – fluid on the exterior of the cell Solutions and Transport

6. Selective Permeability • The plasma membrane allows some materials to pass while excluding others • This permeability includes movement into and out of the cell

7. Diffusion • Particles tend to distribute themselves evenly within a solution • Movement is from high concentration to low concentration, or down a concentration gradient Passive Transport Processes

8. Passive Transport Processes • Types of diffusion • Simple diffusion • Unassisted process • Solutes are lipid-soluble materials or small enough to pass through membrane pores

9. Types of diffusion • Osmosis – simple diffusion of water • Highly polar water easily crosses the plasma membrane Hypertonic- a solution with a high concentration of dissolved solutes Hypotonic- a solution with a low concentration of dissolved solutes Isotonic- solutions have the same concentrations of dissolved solutes. They are in equilibrium • Facilitated diffusion • Substances require a protein carrier for passive transport Passive Transport Processes

10. Crenated- if a cell gives up too much water, it shrivels • Lysis- if a cell swells too much with water, it will burst Passive Transport Processes

11. Diffusion through the Plasma Membrane

12. Passive Transport Processes • Filtration • Water and solutes are forced through a membrane by fluid, or hydrostatic pressure • A pressure gradient must exist • Solute-containing fluid is pushed from a high pressure area to a lower pressure area

13. Transport substances that are unable to pass by diffusion • They may be too large • They may not be able to dissolve in the fat core of the membrane • They may have to move against a concentration gradient • Two common forms of active transport • Solute pumping • Bulk transport Active Transport Processes

14. Active Transport Processes • Solute pumping • Amino acids, some sugars and ions are transported by solute pumps • ATP energizes protein carriers, and in most cases, moves substances against concentration gradients

15. Active Transport Processes

16. Active Transport Processes • Bulk transport • Exocytosis • Moves materials out of the cell • Material is carried in a membranous vesicle • Vesicle migrates to plasma membrane • Vesicle combines with plasma membrane • Material is emptied to the outside

17. Active Transport Processes

18. Bulk transport • Endocytosis • Extracellular substances are engulfed by being enclosed in a membranous vescicle • Types of endocytosis • Phagocytosis – cell eating • Pinocytosis – cell drinking Active Transport Processes

19. Active Transport Processes

20. Cell Diversity

21. Cell Diversity

22. Cell Diversity

23. Cell Diversity