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This 34 page Class Notes was uploaded by Nova Orn on Wednesday September 23, 2015. The Class Notes belongs to BSC 2010 at University of South Florida taught by Ashok Upadhyaya in Fall. Since its upload, it has received 66 views. For similar materials see /class/212647/bsc-2010-university-of-south-florida in Biological Sciences at University of South Florida.
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Date Created: 09/23/15
Chapter 16 DNA Structure and DNA Replication DNA Structure and Replication Overview DNA history details of DNA structure mechanism of DNA replication So GENES are on chromosomesbut what ARE chromosomes 1DNA 2 protein A series of experiments showed conclusively that GENES are made of DNA Griffith AveryMcLeodMcCarty HersheyChase By the early 1950s Genes are made of DNA DNA is a polynucleotide a chain of nucleotides basesugarP has TWO distinct ends 539 and 339 Conformation was NOT known Chargaff s Rules CH3 WU 39 N N quotH a rr H Thylgine T 539 ozT o cng 039 4 Phosphate H 39 OH H Sugar deoxyribose NEH 339 and Guaine G Erwin Chargaff s Hypothesis If DNA somehow encodes genes then there MUST BE chemical differences from species to species Erwin Chargaff Studied the Bases separated them using paper chromatography looked at several different species Conclusions 1 BETWEEN species ratios DIFFERED 2 WITHIN a species ratios were SAME 3 amount ofA T amount of G C Chargaff s Rules Purines Pyrimidines Several Investigators Pursued the DNA Structure Pauling Franklin lWilkins Crick I Watson XRay Crystallography of DNA Watson and Crick Concluded DNA forms a HELIX w UNIFORM WIDTH DNA has TWO polynucleotide chains The backbones are on the OUTSIDE the bases are on the INSIDE The bases HYDROGEN BOND which holds the chains together Hbonding is SPECIFIC Aw T G w C Sugar 0 Sugar Adenine A Thymine T o 7 H Sugar N H 0 sugar H Guanine G Cytosine C Hydrogen Bonding in DNA Explains Chargaff s Rules Why are nucleotides UPSIDE DOWN Strands are antiparallel Conformation of DNA DNA is Measured in Base Pairs 5 end Hydrogen bond 3 and 0 gs 39 u 34 nm Are the chains IDENTICAL KEY CONCEPT The strands are complementary KEY CONCEPT Any order of nucleotides is possible Did a structure of DNA smvsls nuclei Wllnln cells dell and suiwann amlcp lne cell meow Mellie every sell some mm a previwsly exming cell he dlemvelsihel nuclei cumain nucleic acid mlng lscavars chromosomes In nuclei gum are dislingulsnaa as Mn leinls ol nucleic acid cnmniueenlee while RNA is mainly oulside lne nucleus mamm nlemiousirail can belransleneu belween haciena d n anenalee Ihil DNA Is me 93mm mamial in naclevie n se darn mal DNA is me enema malenal l7 hameliophage a meme 9 s Wik ns and Franklin identify me slmclule a DNA st u inluimeliun in human DNA is published lamla39 39n chimpanzee DNA is published paving me way leilnnnans o e mumlenses belween innseNes and on closes living relalnes Functions of DNA 1 DNA encodes PROTEINS and thereby TRAITS Ch 17 2 DNA MUST be copied DNA Structure and Replication Overview mechanism of DNA replication What is the sequence of the other strand 3 AGCATTTAAGC 539 HOW does THE CELL synthesize DNA 1 The two strands are separated 2 Each strand is used as a template to build a new strand HOW KEY CONCEPT Polynucleotides are built by complementary base pairing KEY CONCEPT Replication must be ACCURATE and EFFICIENT Ex In each human cell there are 6 x 109 bp of DNA KEY CONCEPT Like cell divisionone DNA becomes TWO What happens to the old DNA First Pare Cequot replication C m a onservative model lt m b Semiconserva tive model m KEY CONCEPT Each new DNA contains ONE old strand and ONE new strand a Each Old Strand Serves as a Template b C