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DNA Replication

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DNA Replication. Structure of DNA. 1953 | 1962. Watson & Crick developed double helix model of DNA other leading scientists working on question: Rosalind Franklin Maurice Wilkins Linus Pauling. Wilkins. Pauling. Franklin. 1953 article in Nature. Watson and Crick. Watson. Crick. - PowerPoint PPT Presentation

Text of DNA Replication

  • DNA Replication

  • Structure of DNAWatson & Crickdeveloped double helix model of DNAother leading scientists working on question:Rosalind FranklinMaurice WilkinsLinus Pauling 1953 | 1962FranklinWilkinsPauling

  • Watson and Crick1953 article in NatureCrickWatson

  • Rosalind Franklin (1920-1958)

  • Double helix structure of DNAIt has not escaped our notice that the specific pairing we have postulated immediately suggests a possible copying mechanism for the genetic material.Watson & Crick

  • Semiconservative DNA Replication

  • Base pairing in DNAPurinesadenine (A)guanine (G)Pyrimidinesthymine (T)cytosine (C)PairingA : T 2 bondsC : G3 bonds

  • Copying DNAReplication of DNAbase pairing allows each strand to serve as a template for a new strandnew strand is 1/2 parent template & 1/2 new DNAsemi-conservative copy process

  • Replication: 1st stepUnwind DNAhelicase enzyme unwinds part of DNA helixreplication fork

  • DNAPolymerase IIIReplication: 2nd stepBuild daughter DNA strandadd new complementary basesWih the help of DNA polymerase III

  • Fast & accurate!It takes E. coli
  • What does it really look like?

  • Transcriptionfrom DNA nucleic acid language to RNA nucleic acid language

  • How Are Different Types of Cells Created and Maintained?By differential gene expression. The same genetic information is in all 100 trillion cells of any one person. Different cells use the same blueprint in different ways.How?by regulating the flow of information from DNA to protein.

  • 2005-2006RNAribose sugar N-basesuracil instead of thymineU : AC : Gsingle strandedRNADNAtranscription

  • RNARNA is a nucleic acid that uses a different sugar than DNA and the base uracil (U) in place of thymine (T).

  • RNA Is Single-Stranded which allows it to travel in and out of the nucleus

  • There are Different RNAs with Distinct Functions

  • Matching bases of DNA & RNAMatch RNA bases to DNA bases on one of the DNA strandsUAGGGGGGTTACACTTTTTCCCCAAUUUUUGGAAACCCCCCCGGGGAAAAA5'3'

  • TranscriptionThe enzyme RNA polymerase opens the DNA strands and synthesizes an RNA complementary to only one of the DNA strands.RNA polymerase

  • TranscriptionThe decision to transcribe a gene is the most important step in the control of gene expression.Transcription starts and stops at distinct sites at the ends of a gene.

  • The Central DogmaFlow of genetic information in a cellHow do we move information from DNA to proteins?transcriptiontranslationreplicationproteinRNADNAtraitDNA gets all the glory, but proteins do all the work!

  • mRNAFrom gene to proteinDNAtranscriptionnucleuscytoplasmproteintranslationtrait

  • 2007-2008Any Questions??

    *Watson & Cricks model was inspired by 3 recent discoveries:Chargaffs rulesPaulings alpha helical structure of a proteinX-ray crystallography data from Franklin & Wilkins**A chemist by training, Franklin had made original and essential contributions to the understanding of the structure of graphite and other carbon compounds even before her appointment to King's College. Unfortunately, her reputation did not precede her. James Watson's unflattering portrayal of Franklin in his account of the discovery of DNA's structure, entitled "The Double Helix," depicts Franklin as an underling of Maurice Wilkins, when in fact Wilkins and Franklin were peers in the Randall laboratory. And it was Franklin alone whom Randall had given the task of elucidating DNA's structure. The technique with which Rosalind Franklin set out to do this is called X-ray crystallography. With this technique, the locations of atoms in any crystal can be precisely mapped by looking at the image of the crystal under an X-ray beam. By the early 1950s, scientists were just learning how to use this technique to study biological molecules. Rosalind Franklin applied her chemist's expertise to the unwieldy DNA molecule. After complicated analysis, she discovered (and was the first to state) that the sugar-phosphate backbone of DNA lies on the outside of the molecule. She also elucidated the basic helical structure of the molecule.After Randall presented Franklin's data and her unpublished conclusions at a routine seminar, her work was provided - without Randall's knowledge - to her competitors at Cambridge University, Watson and Crick. The scientists used her data and that of other scientists to build their ultimately correct and detailed description of DNA's structure in 1953. Franklin was not bitter, but pleased, and set out to publish a corroborating report of the Watson-Crick model. Her career was eventually cut short by illness. It is a tremendous shame that Franklin did not receive due credit for her essential role in this discovery, either during her lifetime or after her untimely death at age 37 due to cancer. *******Transcription and Translation *G. Podgorski, Biol 1010**To get from the chemical language of DNA to the chemical language of proteins requires 2 major stages:transcription and translation

    Transcription and Translation *G. Podgorski, Biol 1010*Transcription and Translation *G. Podgorski, Biol 1010*Transcription and Translation *G. Podgorski, Biol 1010*Transcription and Translation *G. Podgorski, Biol 1010**Transcription and Translation *G. Podgorski, Biol 1010*Transcription and Translation *G. Podgorski, Biol 1010*Transcription and Translation *G. Podgorski, Biol 1010**To get from the chemical language of DNA to the chemical language of proteins requires 2 major stages:transcription and translationTranscription and Translation *G. Podgorski, Biol 1010***

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