BernsLecture2and3

BernsLecture2and3 - Cells and Cell Surgery I & II...

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Unformatted text preview: Cells and Cell Surgery I & II Chapters 1 & 7 : Berns and Greulich 2007 Berns’ Lab Revised 9/29/10 • Learn about stimulated emission. • In Berns’ 1974 book in library; pages 38- 44. • 1-2 questions on exam. In Berns, 1971 (reserve library) Stimulated Emission Time = ???? Apply lasers (photons) to study cells Review Cell Structure From: Berns, M. Cells (1983) Saunders pub. New York. pg. 6. Typical Plant Cell From: Berns, M. Cells (1983) Saunders Pub. New York. Pg. 7 Cell Wall Chloroplast Vacuole Nucleus chromosom e nucleoplasm nucleolus nuclear envelope & pore 10 – 20 micrometers Cell Cycle (@24hr) M (3 hrs) G1 ( 10 hrs) S (6 hrs) G2 (5 hrs) Chromosome Changes During Cell Cycle Chromosome Duplication two chromatids One chromatid G1 S G2 The “Big” Change Duplicated Chromosomes 2 identical sister chromatids DNA & protein = chromatin fibers High magnification microscope image What is a chromatin fiber? Electron microscope picture showing chromatin fibers Homologous chromosomes Telephone cord knot??? Chromatin fiber Histone proteins Avocado Question: If we strung out all the DNA molecules from a single 20 micron diameter human M or G2 nucleus how far would it go in this room? Look at you thumb! Jasmine = Berns’ student?? Fido another Berns’ student Avocado Question: If we strung out all the DNA molecules from a single human M or G2 cell how far would it go in this room? Total DNA per human cell = 12 9 base-pairs (12,000 Megabases) 46 Mitotic chromosomes = 92 chromatids = 92 DNA molecules 1 chromatid = 130Mbp = 43 mm DNA X 92 DNA molecules 3956 mm = 396 cm = 158 inch. = 13 feet Apply lasers (photons) to study cells History of Laser Scissors “Microbeams” Tschachotin: 1912 - 1952 Tschachotin essis and Nomarsky (Paris), 1962 Commercial ruby laser system, 1967 Original ruby laser, 1961 illumination Berns’ thesis system Ruby Laser How did Berns get into “this business?” do they keep track of the # s during development Berns, M., & W. Keeton. Regulation of segment-building during the post-embryonic development of a common milliped. Science 161: 590-592, 1968. 1967 Great graphics!! 1970’s Courtesy of National Geographic, 158:373 (1976) 1971 Argon ion laser µsec. pulses 0.5 – 1 µ m lesion Laser Scissors & Tweezers Berns M., Scientific American 278: 68, 1998 TWEEZERS SCISSORS SCISSORS TWEEZERS DNA not quite reality What are the factors to consider in using laser “scissors”? Factors/Challenges 1. Determine the focused spot size 2. Understand and control the physics within it. 3. Study biological/medical problems • focus spot size: 1.22(λ)/na na = numerical aperture of microscope objective and it is usually between 1 and 1.4 for high magnification objectives. Size of a focused spot focus spot size = 1.22(λ)/na (memorize) λ = wavelength ( 300 nm – 1.0 µm) na = numerical aperture of microscope objective (1 – 1.4) “ dimensionless number that characterizes the range of angles over which the system can accept or emit light” Focus Spot Sizes Range: 0.26 – 1.22 µm Gaussian Laser Beam Concept...
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This note was uploaded on 12/13/2011 for the course BIOSCI 130 taught by Professor Berns during the Fall '11 term at UC Irvine.

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BernsLecture2and3 - Cells and Cell Surgery I & II...

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