DNA Structure and Replication2/3/200What’s So Special About DNA?DNA is one of the most boring macromolecules imaginable -its made of only four building blocks and has a perfectlymonotonous structure.Worse yet, DNA just sits there - it doesn’t catalyze reactionsor build the cell or organism.So, what’s so good about DNA?The answer lies in DNA’s ability to store and copyinformation.BIOL 213DNA - GENETICSHow Can DNA Store and Copy Information?Key properties that allow these neat tricks are that DNA is a:DNA is also capable of occasional change, andoccasionally, change is good.double stranded molecule ….…. held together by complementary bases …..…… that pair through simple rules.Winners of the Race to Learn DNA’s Structure – Watson andCrick 53 Years AgoBuilding DNA Building BlocksDNA is Made of Two Long Chains of Nucleotides Joined byHydrogen BondsG and C arecomplementary asare A and TA Nucleotide
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DNA Structure and Replication2/3/2008Two Views of the Double HelixDNA is Almost Always Wrapped Around ProteinschromatinThis ….…. not this is what’sfound in the cell.Complementary Base PairingAllows Each Strand of DNAto Serve as a Template forDNA ReplicationDNA is a perfect illustration offunction following form(structure dictates function).DNA Replication – SomethingOld and Something New In EachDaughter MoleculeSimple As It Is in Principle,DNA Replication RequiresMany Enzymes That WorkCoordinatelyDNA polymerases are the firstand foremost of the replicationenzymes.Accidents Happen With Some “Accidents” (Base Mismatches)Leading to MutationA mutation is a heritable change in DNA sequence.Mutations due to replication errors only happen oncein every billion replicated nucleotides.