Chapter 5 - PowerPoint PPT Presentation

sasha
slide1 n.
Skip this Video
Loading SlideShow in 5 Seconds..
Chapter 5 PowerPoint Presentation
play fullscreen
1 / 28
Download Presentation
Chapter 5
148 Views
Download Presentation

Chapter 5

- - - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

  1. Chapter 5 A Closer Look At Cell Membranes

  2. Cell Membranes • Basically similar in all membranes • Fluid mosaic model • Mixed composition • Lipids not fixed in place, can move

  3. Cell membranes • Phospholipids • Glycolipids • Proteins • Glycoproteins • Sterols

  4. phospholipids • Polar head, non-polar tail • Majority of membrane • Provides fluidity

  5. glycolipids • Carbohydrate + Phospholipid • Recognition sites

  6. sterols • Decrease membrane’s fluidity • Developmental signaling • Cholesterol • Hormones

  7. Proteins & glycoproteins • Glycoprotein = Carbohydrate + Protein • Multiple functions within cell membranes

  8. glycoproteins • Peripheral proteins • Only on surface • Cell receptor sites

  9. glycoproteins • Integral proteins • Within the membrane • Channel/Transport Proteins—allow molecules to pass across • Active • Na/K transport failure obesity • Passive • Cystic fibrosis • Adhesion Proteins—connect similar cells into tissues

  10. Glycoproteins • Communication Proteins—channels between cells • Gap junction • Receptor Proteins—Docks for chemicals that signal cell activities • Pygmies • Recognition Proteins—ID self vs. non-self • Blood tranfusion • Organ transplant

  11. glycoproteins

  12. Membrane specializations

  13. Membrane permeability • Selectively permeable • Depends on… • Size • Charge • Polarity • Concentration gradient

  14. Membrane transport • Passive—no energy used • Diffusion—movement of molecules from high to low concentration • Osmosis—movement of WATER from high to low • Concentration gradient • Active—energy used • Movement against gradient • Usually requires carrier molecule

  15. Membrane transport • Endocytosis—creating vesicle to move things into cell • Exocytosis—moving things out of cell by merging vesicle into membrane

  16. Passive tRansport • Diffusion • Movement of molecules • High to low • Simple & Facilitated • Lipid solubility

  17. Passive Transport • Osmosis • Movement of water • High to low • Semipermeable membrane • Based on solute

  18. Diffusion vs. osmosis

  19. Tonicity • Isotonic—Same solute concentration in cell & solution • Hypertonic—More solutes in solution than cell • Hypotonic—Less solutes in solution than cell

  20. tonicity

  21. Tonicity • Plants • Plasmolysis • Turgor pressure • Animals • Crenation • Lysis

  22. Active transport • Requires energy • ATP • Against a gradient • Single movement • Calcium pump • Cotransport • Sodium-potassium pump

  23. Passive vs. active

  24. Surface transport • Exocytosis • Movement of things out of cell • Vescicles • Golgi bodies

  25. endocytosis • Receptor-mediated • Substance binds to receptors, vesicle forms • Phagocytosis—“cell eating” • Engulf food • Pinocytosis—“cell drinking” • Engulf dissolved particles