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Unformatted text preview: Lecture 2 SmartSite: Lec 2 Notes Announcements: None The Cell Plasma Membrane Membrane PotenAal Reading (Recommended): Chapter 2 Chapter 3 1 Principles of the Cell Theory Cell is smallest structural and funcAonal unit capable of carrying out life processes FuncAonal acAviAes of each cell depend on specific structural properAes of the cell Cells are living building blocks of all plant and animal organisms Organisms structure and funcAon ulAmately depend on individual and collecAve structural characterisAcs and funcAonal capabiliAes of its cells 2 Cell Structure Cytoplasm: Organelles Cytosol Cytoplasm Fig. 2-1, pg. 22 3 Nucleus Typically largest single organized cell component Enclosed by a double-layered nuclear envelope Contains cell's geneAc material, DNA DNA funcAons Directs protein synthesis Serves as geneAc blueprint during cell replicaAon 4 Cytoplasm PorAon of cell interior not occupied by the nucleus Consists of Organelles "liSle organs" DisAnct, 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 reAculum Golgi complex Protein and lipid manufacture Processes raw materials into finished products Sorts and directs finished products to their final desAnaAons Serve as intracellular digesAve system Major site of ATP (Energy source) producAon 6 Lysosome Mitochondria 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 ParAcipates in joining cells to form Assues and organs Extremely thin layer of lipids and protein that forms outer boundary of every cell FuncAons 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 Phospholipid Molecule Fig. 3-2a, pg. 54 11 Lipid Bilayer of the Plasma Membrane Fig. 3-2b, pg. 54 12 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 Also has small amount of carbohydrates On outer surface only Cholesterol Tucked between phospholipid molecules Contributes to fluidity and stability of cell membrane Fig. 3-2a, pg. 54 13 Plasma Membrane Structure Proteins FuncAons for membrane proteins ASached 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 interacAon 14 Plasma Membrane Structure Membrane carbohydrates Serve as self-idenAty markers which enable cells to idenAfy and interact with one another Different cell types have different markers Carbohydrate-containing surface markers are also involved in Assue growth 15 Plasma Membrane Structure Fig. 3.3, pg. 55 16 Membrane Transport Cell membrane is selecAvely permeable Permeability (P) reflects ease of movement of an ion or molecule across the membrane. Two properAes of parAcles influence whether they can permeate cell membrane without assistance RelaAve solubility of parAcle in lipid Size of the parAcle 17 Typical Ion Channel 18 AcAve Transport Fig. 3.16, pg. 71 19 Membrane PotenAal 20 Terms to Know PotenAal = V (or E) Current = I Resistance = R RelaAonship: V= I R (Ohm's Law) 21 Forces That Act on Permeant ParAcles: Chemical (ConcentraAon Differences) Fig. 3.8, pg. 62 22 Forces That Act on Permeant ParAcles: Electrical (Charge Differences) 23 Unequal DistribuAon of Ions Fig. 3-20, pg. 77 24 ...
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This note was uploaded on 04/28/2010 for the course NPB 101 taught by Professor Fuller,charles/goldberg,jack during the Spring '08 term at UC Davis.
- Spring '08