15Mar_17 - Biological Science I Tuesdays and Thursdays...

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Biological Science I Tuesdays and Thursdays 8:00-9:15, HCB 102 Mondays 5:15-6:15, KIN 1024 15 March 2011 – Lecture 17 Describe the contributions of the following people: Griffith; Avery, McCary, and MacLeod; Hershey and Chase; Chargaff; Watson and Crick; Franklin; Meselson and Stahl Describe the structure of DNA Describe the process of DNA replication; include the following terms: antiparallel structure, DNA polymerase, leading strand, lagging strand, Okazaki fragments, DNA ligase, primer, primase, helicase, topoisomerase, single-strand binding proteins Describe the function of telomeres Compare a bacterial chromosome and a eukaryotic chromosome ISOTOPES Different forms of the same element Have different numbers of neutrons in the nucleus Two different isotopes of a given element have the SAME number of PROTONS (of course), but each has a DIFFERENT number of NEUTRONS in its nucleus. Having DIFFERENT number of NEUTRONS makes an atomic nucleus unstable Radioactive decay is the process by which an unstable atomic nucleus loses energy by emitting ionizing particles or radiation. REMEMBER isotopes have the "normal" number of electrons, so behave well in chemical reactions. IMPORTANCE: If we build a molecule with a radioactive element (like DNA with radioactive phosphorus, or protein with radioactive sulfur) we can now "see" or "trace" where the molecule is. LANDMARKS IN THE UNDERSTANDING OF DNA AS THE GENETIC MATERIAL Six seminal lines of inquiry: o Griffith - demonstrations of bacterial transformation o Avery McCarty and MacLeod – Transforming factor is separable o Hershey and Chase – Transforming factor is DNA o Chargaff – Ratios of DNA within and between species o Watson and Crick – DNA structure o Franklin – DNA structure o Meselson and Stahl – Semi-conservative replication 1. Griffith - a. The discovery of the genetic role of DNA began with research by Frederick Griffith in 1928 b. Griffith worked with two strains of Streptococcus pneumoniae one pathogenic (smooth) and one harmless (rough). c. The smooth bacteria produced a peptidoglycan that makes it impossible for phagocytosos to occur - thus lethal 1
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Biological Science I Tuesdays and Thursdays 8:00-9:15, HCB 102 Mondays 5:15-6:15, KIN 1024 15 March 2011 – Lecture 17 d. Rough bacteria could be phagocytosed - thus non-lethal e. When he mixed heat-killed remains of the pathogenic strain with living cells of the harmless strain, some living cells became pathogenic f. IMPORTANTLY: the once "R" bacteria were now "S" and were now "S" permanantly, generation after generation. g. He called this phenomenon transformation, now defined as a change in genotype and phenotype due to assimilation of foreign or external DNA h. The material that was responsible for the transformation was called "transforming factor" 2. Avery, McCarty and Macleod a. In 1944, Oswald Avery, Maclyn McCarty, and Colin MacLeod announced that the transforming substance was DNA
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This note was uploaded on 11/07/2011 for the course BIO bsc2010 taught by Professor Trombley during the Spring '08 term at FSU.

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15Mar_17 - Biological Science I Tuesdays and Thursdays...

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