3DNA & Genetic Information DNA as genetic material Expression of Biological InformationDNA & Genetic InformationOperonAbilities of DNAProduce polypeptideForming new DNADNA as genetic materialGene hypothesisProtein synthesisGriffith (1931)Beadle & Tatum (1944)ReplicationAvery et. al (1944)Hershey & Chase
4At the end of the lesson, you should be able to : Explain DNA as the carrier of genetic information.Explain gene concept : One gene one polypeptideDescribe the semi-conservative replication of DNA
5Carrier of genetic information DNA as genetic materialCarrier of genetic information
6Streptococcus pneumoniae DNA as genetic material…Frederick Griffith (1931)Streptococcus pneumoniaemouseTwo typesMutant typeRough, non-virulent(IIR)Wild typesmooth, virulent(IIIS)
7DNA as genetic material… Frederick Griffith (1931)Sample 1
8DNA as genetic material… Frederick Griffith (1931)Sample 2
9DNA as genetic material… Frederick Griffith (1931)Sample 3
10Living S cells found in the blood DNA as genetic material…Frederick Griffith (1931)Sample 4Living S cells found in the blood
11What is the transforming agent? DNA as genetic material…Frederick Griffith (1931)conclusionLiving R cells are converted to S cells.Transformation occurred.What is the transforming agent?
12Concepts of transformation DNA as genetic material…Concepts of transformationTransformation is a types of genetic transfer found in bacteria.Bacteria can take up the externally DNA.
13DNA as transforming agent DNA as genetic material…DNA as transforming agentOswald T. AveryColin MacLeodMaclyn McCarty
14DNA as transforming agent DNA as genetic material…DNA as transforming agentS strain(killed)R strain(living)+centrifugationproteaseRNaseDNaseProtein destroyedRNA destroyedDNA destroyedLipid eliminatedLiving S cellsLiving S cellsLiving R cellsLiving S cellsNo transformation
15DNA as genetic material… Avery et. al (1944)conclusionThe strain without DNA caused no transformation occur.So, the transformation agent is DNA!
16DNA as genetic material… Hershey and ChaseProve that DNA is the molecules that responsible as genetic information, not protein.Bacteriophages
17One gene one polypeptide Gene HypothesisOne gene one polypeptide
19Gene Hypothesis…George Beadle and Edward Tatum experiment: connection between genes & metabolism.Neurospora crassa as experimental organism.- short life-cycle, easily grown.Since it is haploid for much of its life cycle, mutations would be immediately expressed.
20Gene Hypothesis…Neurospora crassa able to synthesize all of the amino acids and other chemicals needed for growthMutations will affect a single genes and single enzymes in specific metabolic pathways.
23Case2 Case 1 Case 3 Minimal Nutrient Minimal Nutrient Gene Amino acid EnzymeAmino acidWild type neurosporaMutant neurosporaMinimal NutrientMinimal Nutrient
24X X X X X X + Ornithine + Citrulline + Arginine How to make sure ONE genes is only code ONE polypeptide???Is the gene C only produce enzyme C only?Is the gene B only produce enzyme B only?Is the gene A only produce enzyme A only?Gene AGene BGene CPrecursorXXEnzyme A+OrnithineOrnithineXXEnzyme B+CitrullineCitrullineXXEnzyme CArginine+Arginine
25Beadle & Tatum Experiment Gene Hypothesis…Beadle & Tatum ExperimentconclusionEach gene will produce certain enzyme (polypeptide)One gene one polypeptide.
27DNA Replication Model… Proposed by Matthew Meselson (left) and Franklin W. Stahl (right) in 1958.
28DNA Replication Model… Process of copying a double stranded DNA strand which is the two resulting double strands are identical and each of them consist of one original and one newly synthesize strand.
29DNA Replication Model… Watson and Crick suggest that each strands of DNA molecule could serve as template for the synthesis of opposite strand.Each half-helix could pair with their complementary nucleotides to replace its missing partner.Will result two DNA double helices, each identical to the original.
30Studied the replication in E. coli DNA Replication Model…Meselson & Stahl (1958)Studied the replication in E. coli3 hypothesesconservativesemiconservativedispersiveWhich one is the model of DNA replication?
31Both parent strand remain together and all new copies is made. DNA Replication Model…Meselson & Stahl (1958)Hypothesis 1conservativeBoth parent strand remain together and all new copies is made.
32DNA Replication Model… Meselson & Stahl (1958)Hypothesis 2semiconservativeThe 2 strand of the parental molecule separate and each functions as a template for synthesis of a new complementary strand
33DNA Replication Model… Meselson & Stahl (1958)Hypothesis 3dispersiveEach strand of both daughter molecules contains a mixtureof old and newly synthesized parts