100 likes | 214 Views
DNA Deoxyribonucleic Acid. Dr. Jim Bidlack University of Central Oklahoma jbidlack@ucok.edu http://biology.ucok.edu/bidlack. Special thanks to John Wilson for providing the template of this presentation in partial fulfillment for Cell Physiology (BIO 4454) during the Fall 2002 Semester.
E N D
DNADeoxyribonucleic Acid Dr. Jim Bidlack University of Central Oklahoma jbidlack@ucok.edu http://biology.ucok.edu/bidlack Special thanks to John Wilson for providing the template of this presentation in partial fulfillment for Cell Physiology (BIO 4454) during the Fall 2002 Semester.
History of DNA • Fred Griffith and the mouse experiment • Transforming “principle” • Oswald Avery’s conclusion of DNA as the transforming principle • Isolation of DNA • Watson & Crick’s Double Helix • Sugar, phosphate, base
Structure of DNA • DNA is a double helix made of complimentary antiparallel strands • The backbone is constructed of a five carbon sugar and a phosphate group • The rungs consist of the different bases held together by hydrogen bonds
Structure of Nucleic Acids • DNA is a five carbon sugar with two hydrogens on the second carbon • RNA is a five carbon sugar with a hydrogen and hydroxyl group on the second carbon
Structure of the DNA Bases • Two classes of bases: Purines and Pyrimidines • Purines consist of Adenine (A) and Guanine (G) • Pyrimidines consist of Thymine (T) and Cytosine (C) • Bases are the same in RNA except that Uracil (U) is substituted for Thymine
Backbone Linkage • Any nucleotide can be connected with a phosphodiester bond • Nucleotides are triphosphated • The 5’ ends with a phosphate and the 3’ ends with a hydroxyl • The phosphate is attached to the 5’ carbon and the 3’ carbon of the sugar • The bases are attached to the first carbon
DNA Linkage • Helix is anti-parallel and complimentary • Left side is from 5’ end to 3’ end • Right side is from 3’ end to 5’ end • A matches with T stabilized by two hydrogen bonds • C matches with G stabilized by three hydrogen bonds
DNA Replication • Replication is semi-conservative • Each strand is a template for another strand • New DNA strands contain one new strand and one parental strand • Bases on strands are complimentary (A w/ T & C w/ G)
DNA Replication • DNA synthesizes in one direction, from the 5’ end to the 3’ OH end • Many enzymes contribute in the replication of DNA • Helicases - unwind the DNA • Topoisomerases - releases the tension • Single Stranded Binding Proteins - maintain the single strands after unwinding • DNA polymerases - add nucleotides and reads the template strand. There are five polymerases for mammals. Must have a 3’ OH end
Summary • DNA is a double helix with complementary anti-parallel strands • DNA consists of sugar, phosphate and bases • There are two classes of bases: Purines and Pyrimidines • Nucleotides are connected by a phosphodiester bond • Replication is semi-conservative from the 5’ end to the 3’ end and involves several enzymes