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Cells

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.

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Cells

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  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

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