Biomembranes & Cell Surface.pdf

BIOMEMBRANES & CELL SURFACE Mr. Prashant Masali, Head, Department of Biochemistry, Ramnarain Ruia Autonomous College, Matunga, Mumbai – 400 019. WRITE ANY 5 FACTS ABOUT CELL 2 WRITE ANY 5 FACTS ABOUT CELL MEMBRANE...

BIOMEMBRANES & CELL SURFACE Mr. Prashant Masali, Head, Department of Biochemistry, Ramnarain Ruia Autonomous College, Matunga, Mumbai – 400 019. WRITE ANY 5 FACTS ABOUT CELL 2 WRITE ANY 5 FACTS ABOUT CELL MEMBRANE 3 WHAT IS CELL MEMBRANE ?  The cell membrane (also called the plasma membrane or plasmalemma) is a biological membrane separating the interior of a cell from the outside environment  It appears in thin sections with the electron microscope as a triple-layered structure about 7.5–10 nanometers thick  The cell membrane is flexible and allows a unicellular organism to move 4 FUNCTION OF CELL MEMBRANE  Maintain a steady environment: Homeostasis  Protective barrier  Regulate transport in & out of cell (selectively permeable)  Small lipid-soluble molecules, e.g. oxygen and carbon dioxide can pass easily  Water can freely move cross the membrane 5  Ions and large molecules cannot cross without assistance  Allow cell recognition  Provide anchoring sites for filaments of cytoskeleton  Provide a binding site for enzymes  Interlocking surfaces bind cells together (junctions)  Contains the cytoplasm (fluid in cell) 6 TYPE OF TRANSPORT  Passive transport: Simple diffusion Facilitated diffusion: channel, carrier Osmosis  Active transport: Pump  Bulk membrane transport: Endocytosis: pinocytosis, phagocytosis, receptor mediated Exocytosis 7  FLUID MOSAIC MODEL  In 1972 SJ Singer and GL Nicolson proposed fluid mosaic model.  Fluid – Individual phospholipids and some proteins can move sideways (laterally) in each layer-therefore FLUID  Mosaic – Range of different proteins resting on the surface on through the phospholipid layer gives it a mosaic appearance. 8 CHEMICAL COMPOSITION OF PLASMA MEMBRANE 9 10 POINTS TO THINK…  Carnitine shuttle  Exocytosis (Ab production)  Why these oligosaccharide are called Blood Group Ag? 11 12 13 14 15 16 17 18 19 20 21 22