Unformatted text preview: Lecture 2 SmartSite: Lec 2 Notes Announcements: All students not enrolled, contact Debbie Abbo8 at [email protected] for a PTA. This must be used within 72 hours of receipt. Erin's Ofc Hrs are T/R 1-3 The Cell Plasma Membrane Membrane PotenQal Reading (Recommended): Chapter 2 Chapter 3 1 Principles of the Cell Theory Cell is smallest structural and funcQonal unit capable of carrying out life processes FuncQonal acQviQes of each cell depend on specific structural properQes of the cell Cells are living building blocks of all plant and animal organisms Organisms structure and funcQon ulQmately depend on individual and collecQve structural characterisQcs and funcQonal capabiliQes of its cells 2 Cell Structure Cytoplasm: Organelles Cytosol Cytoskeleton Fig. 2-1, pg. 22 3 Nucleus Typically largest single organized cell component Enclosed by a double-layered nuclear envelope Contains cell's geneQc material, DNA DNA funcQons Directs protein synthesis Serves as geneQc blueprint during cell replicaQon 4 Cytoplasm PorQon of cell interior not occupied by the nucleus Consists of Organelles "li8le organs" DisQnct, highly organized, membrane-enclosed structures Cytosol (~55% of internal cell volume) Complex, gel-like mass in which the cytoskeleton is found Cytoskeleton Bone and muscle of the cell 5 Examples of Organelles Endoplasmic reQculum Golgi complex Protein and lipid manufacture Processes raw materials into finished products Sorts and directs finished products to their final desQnaQons Serve as intracellular digesQve system Major site of ATP (Energy source) producQon Lysosome Mitochondria 6 Plasma Membrane 7 Plasma Membrane Fig. 3-2c, pg 54 8 Plasma Membrane Also called the cell membrane Surrounds every cell Separates cell contents from its surroundings Separates two environments: ICF and ECF ICF = Intracellular Fluid ECF = Extracellular Fluid Controls movement of molecules between the cell and its environment Plays important role in the ability of a cell to respond to changes in the cell's environment 9 Plasma Membrane ParQcipates in joining cells to form Qssues and organs Extremely thin layer of lipids and protein that forms outer boundary of every cell FuncQons of lipid bilayer Forms basic structure of the membrane Hydrophobic interior serves as barrier to passage of water soluble substances between ICF and ECF Responsible for fluidity of the membrane 10 Lipid Bilayer of the Plasma Membrane Fig. 3-2b, pg. 54 11 Plasma Membrane Structure Fluid lipid bilayer embedded with proteins Most abundant lipids are phospholipids Polar end of phospholipid is hydrophilic Nonpolar end of phospholipid is hydrophobic On outer surface only Tucked between phospholipid molecules Contributes to fluidity and stability of cell membrane Also has small amount of carbohydrates Cholesterol Fig. 3-2a, pg. 54 12 Plasma Membrane Structure Proteins FuncQons for membrane proteins A8ached to or inserted within lipid bilayer Span membrane to form water-filled pathways, or channels across lipid bilayer Serve as carrier molecules Serve as docking-marker acceptors Membrane-bound enzymes Receptor sites Cell adhesion molecules (CAMs) Proteins on surface are important in cells' ability to recognize "self" and in cell-to-cell interacQon 13 Plasma Membrane Structure Membrane carbohydrates Serve as self-idenQty markers which enable cells to idenQfy and interact with one another Different cell types have different markers Carbohydrate-containing surface markers are also involved in Qssue growth 14 Plasma Membrane Structure Fig. 3.3, pg. 55 15 Membrane Transport Cell membrane is selecQvely permeable Permeability (P) reflects ease of movement of an ion or molecule across the membrane. Two properQes of parQcles influence whether they can permeate cell membrane without assistance RelaQve solubility of parQcle in lipid Size of the parQcle 16 Typical Ion Channel 17 AcQve Transport Fig. 3.16, pg. 71 18 Membrane PotenQal 19 Forces That Act on Permeant ParQcles: Chemical (ConcentraQon Differences) Fig. 3.8, pg. 62 20 Forces That Act on Permeant ParQcles: Electrical (Charge Differences) 21 Unequal DistribuQon of Ions Fig. 3-20, pg. 77 22 ...
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- Fall '08