BIO 243 1st Edition Lecture 6Outline of Last Lecture I. Organelles Ctd.a. Ribosomesb. Endoplasmic Reticulumc. Golgi Apparatusd. Lysosomese. VesiclesII. PathwayIII. Cytoskeletona. FilamentsIV. NucleusV. Plasma MembraneOutline of Current Lecture I. Plasma Membrane Ctda. Proteinsi. Functions b. Specializations c.c. Transporti. Passiveii. ActiveCurrent LectureI. Plasma Membrane ctd.a. Proteinsi. Integral Proteins1. Part of the protein is inserted into the lipid bilayer (hydrophobic core)2. Trans membrane proteinsa. Go from one end of the phospholipid bilayer to another3. Peripheral proteinsa. Stuck on the outside of the bilayerb. Do not interact with the inside of the phospholipid bilayerii. Glycoproteinsiii. Functions of proteins1. Essential for transporta. Nonpolar molecules need proteins to help transport them across the membraneb. Very specific2. Serve as receptors for signal transductiona. Specifically bind to signals which initiates a chain of chemical reactions in the cell3. Involved in attachment to the extracellular matrixa. Anchors cell in certain environments which help maintain shape and fix locations of certain proteins4. Enzymatic Activitya. Proteins are built into the membranes and can act as enzymes with an exposed active site5. Intercellular joininga. Proteins are responsible for two cells binding together6. Cell to cell recognition a. Mediate cell to cell interactions and allow cells to be recognized by other cellsb. Specializationsi. Microvilli 1. Occurs on the small intestine2. Shape increases the surface areaa. Important in digestion and absorptionii. Membrane junctions1. Tight junctionsa. Membranes of two cells fusing togetherb. Prevent molecules from passing thorugh the intercellular space2. Desmosomesa. Cells are held together by filamentsb. Very strongc. Various typesi. Ex. Plaque d. Found especially in the skin3. Gap junctionsa. Passage way (channel) between the cellsb. Substances can easily pass throughc. Found in smooth musclec. Transporti. Passive 1. No energy required for transport to occur2. Always goes down a concentration gradient3. Simple Diffusiona. Molecules are continuously moving randomly b. Conditionsi. Hotter – diffuse fasterii. Smaller – diffuse fasterc. Simple diffusion is fori. Nonpolar molecules1. O2, CO2ii. Very small polar molecules d. Osmosisi. Diffusion of a water through a semipermeable membraneii. Water goes from areas of low concentration to high concentratione. Tonicityi. The ability of a solution to change shapeii. Isotonic1. Concentration is equal on the inside andout2. No change in shapeiii. Hypertonic1. Concentration of the outside of the cell is greater on the outside than the inside2. Water leaves the cell so the cell shrinks3. Turgid (shrinks)iv. Hypotonic 1. Concentration of the inside of the cell is greater than the outside2. Water comes into the cell so the cell swells3. Lyse (bursts)4. Facilitated Diffusiona. For polar or charged moleculesb. Down a concentration gradientc. Can go through two types of Proteinsi. Channel proteins1. Allow ions to pass based on size and chargeii. Carrier proteinsd. Very specifice. Regulatedi. Cells can alter what kind of molecules are to be transportedii. Active1. Energy is required for transport to occura. Typically ATP  ADP 2. Molecules go up a concentration gradient3. For certain ions, some amino acids, and some sugars4. Sodium Potassium Pumpa. It is responsible for i. Sodium gradient from inside outii. Potassium gradient from outside in5. Vesicular or Bulk transporta. Exocytosisi. Secretion of molecules by vesiclesii. Ex.) Mucus, neurotransmittersb. Endocytosis i. Bringing of things into the cells by vesiclesii. Phagocytosis1. For particles - Bacteria, microorganisms2. WBC and macrophages do this3. Receptor processa. A cell engulfs a large particle and brings it into the cellb. Brings the particle to the lysosomes which then ingests it iii. Pinocytosis1. For liquids2. The cell is “sipping” the extracellular fluid and bringing it to the lysosomes3. Nonspecificiv. Receptor-mediated1. Very specific2. For molecules3. Molecules bind to specific receptors which enables the cell to take it to the lysosomes where it is ingested and destroyed or