Ch03-The Cellular Level of Organization.rtf - Chapter 3 The...

This preview shows page 1 - 4 out of 18 pages.

Chapter 3The Cellular Level of OrganizationSuggested Lecture OutlineINTRODUCTION0A cell is the basic, living, structural, and functional unit of the body.1Cytology is the study of cell structure, and cell physiology is the study of cell function.PARTS of a CELLA.A generalized view of the cell is a composite of many different cells in the body. No singlecell includes all of the features seen in the generalized cell.B.The cell can be divided into three principal parts for ease of study.1. Plasma (cell) membrane2. Cytoplasma. Cytosolb.Organelles (except for the nucleus)3. NucleusTHE PLASMA MEMBRANEA. The plasma membrane is a flexible, sturdy barrier that surrounds and contains thecytoplasm of the cell.1.The fluid mosaic model describes its structure.2.The membrane consists of proteins in a sea of lipids.B. The Lipid Bilayer1.The lipid bilayer is the basic framework of the plasma membrane and is made up ofthree types of lipid molecules: phospholipids, cholesterol, and glycolipid.Dr. D.Page 1
2.The bilayer arrangement occurs because the lipids are amphipathic molecules.They have both polar (charged) and nonpolar (uncharged) parts with the polar “head”of the phospholipid pointing out and the nonpolar “tail” pointing toward the center of themembrane.3.Cholesterol molecules are weakly amphiphotic and are interspersed among otherlipids.4.Glycolipids appear only in the membrane layer which faces the extracellular fluid.C. Arrangement of Membrane Proteins1.The membrane proteins are divided into integral and peripheral proteins.a.Integral proteins extend into or across the entire lipid bilayer among thefatty acid tails of the phospholipid molecules.b.Peripheral proteins are found at the inner or outer surface of the membraneand can be stripped away from the membrane without disturbing membraneintegrity.2.Integral membrane proteins are amphipathic.a.Those that stretch across the entire bilayer and project on both sides of themembrane are termed transmembrane proteins.b.Many integral proteins are glycoproteins.3.The combined glycoproteins and glycolipids form the glycocalyx which helps cellsrecognize one another, adhere to one another, and be protected from digestion byenzymes in the extracellular fluid.D. Functions of Membrane Proteins1.Membrane proteins vary in different cells and functions as channels (pores),transporters, receptors, enzymes, cell-identity markers, and linkers.Dr. D.Page 2
2.The different proteins help to determine many of the functions of the plasmamembrane.E. Membrane Fluidity1.Membranes are fluid structures, rather like cooking oil, because most of themembrane lipids and many of the membrane proteins easily move in the bilayer.2.Membrane lipids and proteins are mobile in their own half of the bilayer.

Upload your study docs or become a

Course Hero member to access this document

Upload your study docs or become a

Course Hero member to access this document

End of preview. Want to read all 18 pages?

Upload your study docs or become a

Course Hero member to access this document

Term
Fall
Professor
N/A
Tags

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture