BCMB 230 1st Edition Lecture 3 Outline of Last Lecture I.Chemical BondsII.MacromoleculesIII.Protein Structure and FunctionOutline of Current Lecture I.CellsII.Plasma MembraneIII.Membrane ProteinsIV.Characteristics of MembranesV.Membrane JunctionsVI.CytoplasmVII.OrganellesCurrent LectureCell Structure and FunctionCellsDivide into plasma membrane and cytoplasmPlasma membrane-limiting barrier surrounding a cell; also called a cell membrane; responsible for a lot of physiological processesCytoplasm-collectively everything inside the cell membrane-cytosol-organelles (membranous and nonmembranous)Cells are specialized- have different shapes and functions-not all cells are small or microscopic (ex. nerve cells, muscle cells length of arm)-nucleus shape, size, and location varies depending on cell type-can tell the difference between white blood cells and red blood cells by the nucleus-shape of nucleus in white blood cells-red blood cells lack a nucleusPlasma MembranePlasma membrane-consists of a phospholipids bilayerThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.-phospholipids have polar and non polar ends; arranged this way because of interaction with water (cytosol on the inside; interstitial fluid/extracellular on the outside)-anything lipid-soluble goes into the cell-most chemicals in our body are water-soluble so the plasma membrane is a good boundaryIf you need to get something water-soluble into the cell—use proteinsMembrane proteinsTwo main types of membrane proteins:Integral proteins-embedded in bilayer; many but not all integral proteins may be transmembrane (completely cross the membrane); can also be stuck on one side, embedded into the membranePeripheral proteins-on the inside of the cell and lie next to or on the surface of the plasma membrane; have a nonpolar tail that anchors it to the membrane; not embedded (not asfirmly attached)Transmembrane protein can provide for transport of water-soluble material through the membrane (one way or another); spans the plasma membrane-Transporters-can move slightly bigger materials (polyatomic ions); actually have to have a shape change to get the material moved across the membrane-Channels-have a protein structure so that there is a passageway through the middle of the protein (big tube which water or a small ion can go through)-channels can be very specific (can have sodium channels, calcium channels, etc)-channels can also be gated (can open and close):-mechanical gating-ligand gated-voltage gatedDifferent functions of membrane proteins:-Channels (have to be integral)-Transporters (have to be integral)-Receptors (can be either)-Enzymes (can be either)-Structural (can be either)Characteristics of MembranesGlycocalyx-fuzzy coating on extracellular surface of plasma membrane; consists of short, branched carbohydrate chains; carbohydrate component only on the outside of the cell that can attach to proteins or lipids; can attach to a protein to form a glycoprotein or a lipid to form a glycolipid -Difference in blood types is the difference between something with the glycocalyxCholesterol- found in the plasma membrane (lipid-soluble); found in nonpolar (middle) portion of membrane; helps maintain fluidity of plasma membrane; helps to stabilize cell membrane over temperature changes-creates steroids-in excess, can be badMembrane JunctionsSpecial Junction-ways that cells are attached to each other-epithelial layer- basement membrane or basal lamina that helps to hold the cells in place-can influence what gets down between the cells-movement across the epithelium-paracellular transport-material slips down in between the cells/goes between cells; we have less control over this one, depends on the space between cells and the nature (chemical composition)-transcellular transport- material goes all the way through a cell (centers one side, leaves through the other side); cross the membrane twice, through the cell then the epithelial layerDesmosome-hold cells together, giving them support; but not controlling transport; have spaceswhere things can get around; cells connected by shared/overlapping proteins but there is still room for paracellular transportTight junction-seals up gaps between the cells; give lots of control of what moves through the epithelial; cells connected by shared/overlapping portiens, but there is no room between cells which forces transcellular transport-look at this mostly in epithelial cellsGap junction- provides passage way between adjacent cells without going outside the cell; helpsto coordinate cell activity (not usually in epithelial cells but muscle cells and others)Cytoplasm Cytosol-water and proteins, salts, sugars, and various waste products dissolved in water-generally kind of syrupy; proteins give it a little more viscosity-fills up the inside of the cellOrganelles Nonmembranous organelles:-Cytoskeleton-provides shape and structure; made with proteins that come in long strands called filaments -microtubule-filament made from protein called tubulin; has the biggest diameter; can provide for movement as well as structure-produce cilia and flagella on outside-movement of chromosomes during mitosis is controlled by microtubules-Cilia and Flagella-have microtubles inside of them; allows them to bend; movement of cilia is important for movement of materials-Ribosome-site of making proteins in the cell; may be free (scattered throughout cytosol); may be associated with membranous organelles; site of making proteins in the cell-free-floating—proteins created are used inside the cell-attached to organelle—proteins created are transported outside cell or to cell membraneMembranous Organelles:-membranes are similar to plasma membrane except with no glycocalyx-Nucleus-has a double membrane; membrane has holes in it called nuclear pores which is the only place where you can easily get large molecules across the membrane; this cannot be seen in any other membrane-Chromatin (inside nucleus)- combination of DNA and proteins; DNA has coding telling what amino acids sequence is for every protein in every cell-Mitochondrion-also has double membrane, site of ATP (energy) synthesis-number present depends on how much energy cell needs-Endoplasmic reticulum- can form flattened sacs or more tubular structures in the cell-Rough Endoplasmic Reticulum-more flattened reticulums usually have ribosomes attached; 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