dna & dna replication. history dna dna comprised of genes in non-dividing cell nucleus as chromatin...

Download DNA & DNA Replication. History DNA DNA Comprised of genes In non-dividing cell nucleus as chromatin Protein/DNA complex Chromosomes form during cell division

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  • DNA & DNA Replication

  • HistoryDNAComprised of genesIn non-dividing cell nucleus as chromatinProtein/DNA complexChromosomes form during cell divisionDuplicate to yield a full set in daughter cell

  • From Chapter 3Nucleic acids are polymersMonomers are called nucleotidesNucleotides = base + sugar + phosphateBase = adenine, guaninethymine, cytosine, uracilSugar = deoxyribose or ribosePhosphate, a single phosphate in DNASugar is linked to the phosphate

  • DNA is a Double HelixNucleotidesA, G, T, CSugar and phosphate form the backboneBases lie between the backboneHeld together by H-bonds between the basesA-T 2 H bondsG-C 3 H bonds

  • H - BondsBase-pairing rulesAT only (AU if DNA-RNA hybrid)GC only

  • Double Helix

  • Nucleotides as LanguageWe must start to think of the nucleotides A, G, C and T as part of a special language the language of genes that we will see translated to the language of amino acids in proteins

  • Genes as Information TransferA gene is the sequence of nucleotides within a portion of DNA that codes for a peptide or a functional RNASum of all genes = genome

  • DNA ReplicationSemiconservative Daughter DNA is a double helix with 1 parent strand and 1 new strandFound that 1 strand serves as the template for new strand

  • DNA TemplateEach strand of the parent DNA is used as a template to make the new daughter strandDNA replication makes 2 new complete double helices each with 1 old and 1 new strand

  • How is DNA Synthesized?DNA is synthesized bySimple addition of nucleotides along one strand (1/2 the double helix)

  • Mistakes during ReplicationBase pairing rules must be maintainedMistake = genome mutation, may have consequence on daughter cellsOnly correct pairings fit If wrong nucleotide is includedSpecial enzyme has proofreading and can remove incorrect nucleotideAnother enzyme then adds correct base

  • Proofreading

  • Other Necessary ProteinsHelicase opens the double helix and helps it uncoilSpecialized binding proteins keep strands separated

  • DNA RepairFor the rare mutations occurring during replication that isnt caught by DNA proofreading enzymeIf no repairIn germ (sex) cells inherited diseasesIn somatic (regular) cells cancer

  • Effect of Mutation

  • Repair MechanismsDifferent enzymes correct different mistakesOther enzymes make the proper strand pieceStill another enzyme will join new the new piece in its proper spot on the strand


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