Bios 208 1st Edition Lecture 14 Outline of Last Lecture I. Activation energyII. EnzymesIII. Early MicroscopyOutline of Current Lecture I. Cell theoryII. MicroscopyIII. A prokaryotic cellIV. Cell SizeCurrent LectureI. Cell theoryA. Cell Theory (1830’s -1850’s; Schwann, Schleiden, Virchow, others)B. All organisms are composed of one or more cellsC. The cell is the smallest, simplest unit of lifeD. All cells arose by division of pre-existing cellsE. Implications: Life evolved once. All organisms are descended from these cells.II. MicroscopyA. Units (e.g., 1 m = 1000 mm = 106 μm = 109 nm)a) Cell dimensions (on each side):b) Prokaryotic cell: ~ 1-10 μmc) Eukaryotic cell: ~ 10-100 μmB. Resolution is the ability to discern fine detail. Approximate limits of practical resolution are:a) Human eye: 0.2 mmb) Light microscope: 0.2 μm (~1000x better than eye)c) Electron microscope: 2 nm (~100x better than LM)III. A prokaryotic cellA. Major componentsa) Plasma membrane: permeability barrierb) Cytoplasm: salts, small molecules, macromolecule subunits, enzymes, etc.c) DNA: in a nucleoid; one circular chromosomed) Ribosomes: protein synthesisThese 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.e) Cell wall: protection; prevents osmotic rupturef) Flagella: movementg) Pili and capsule: interaction with other cells and environmenth) No organellesB. Bacillus polymyxa is famous for making antibiotic polymyxin B effective mainly against gram-negative organisms like pseudomonas aeruginosa, which may cause septicemia, meningitis, urinary tract infections, and middle ear infections.a) Bacteria like this are prokaryotesb) Cells are small and structurally simplec) Mostly unicellular, some coloniesd) DNA but no nucleie) Physiologically complex, “masters of adaptation”f) 2 of 3 domains of lifeg) Bacteria and ArchaeaIV. Cell SizeA. Why are cells small?a) Small cells have a high surface area to volume ratio (SA:Vol). This ratio must be optimal.b) Large organisms are made from many small cells, not a few large cells.c) This allows efficient transport of materials into and out of a cell if there is more membrane relative to cell volume. Goodies in; Garbage out “GiGo”d) Small volumes allow more efficient communication inside cell and allows the nucleus to direct events in the cell..e.g. protein synthesis.e) Animal Cells are 10-100 micrometers in sizei. 1 micrometer = 1x10-6
View Full Document
Unlocking...