molecular genetics lecture
TRANSCRIPT
Molecular GeneticsMolecular Genetics
Paul Rindler M.S.Paul Rindler M.S.
TopicsTopics
Discovery of DNA Discovery of DNA DNA structure and replicationDNA structure and replication Gene expression and protein Gene expression and protein
synthesissynthesis Biotechnology toolkitBiotechnology toolkit VirusesViruses
Discovery of DNADiscovery of DNA
1800’s1800’s Johann Miescher isolated a phosphorous Johann Miescher isolated a phosphorous
containing acidic compound from the containing acidic compound from the nucleusnucleus
19281928 Frederick Griffith demonstrates the Frederick Griffith demonstrates the
existence of a chemical in bacteria that existence of a chemical in bacteria that caries genetic informationcaries genetic information
Discovery of DNADiscovery of DNA
1930’s1930’s Various experiments identify chromosomes Various experiments identify chromosomes
as the source of genetic informationas the source of genetic information Chromosomes are composed of mainly Chromosomes are composed of mainly
proteins and deoxyribonucleic acid (DNA)proteins and deoxyribonucleic acid (DNA) The DNA molecule was considered too The DNA molecule was considered too
simple to be important so proteins were simple to be important so proteins were thought to carry the genetic informationthought to carry the genetic information
Discovery of DNADiscovery of DNA
19441944 Oswald Avery showed that degradation Oswald Avery showed that degradation
of DNA and not protein resulted in loss of DNA and not protein resulted in loss of genetic informationof genetic information
Discovery of DNADiscovery of DNA Rosalind Franklin (1951)Rosalind Franklin (1951)
Generated X-ray Generated X-ray crystallography data crystallography data suggesting a double helix suggesting a double helix with phosphates on the with phosphates on the outsideoutside
Discovery of DNADiscovery of DNA Watson & Crick (1953)Watson & Crick (1953)
Used Franklin’s data to develop a model for DNAUsed Franklin’s data to develop a model for DNA Received a Nobel Prize in 1962Received a Nobel Prize in 1962
TopicsTopics
Discovery of DNA Discovery of DNA DNA structure and replicationDNA structure and replication Gene expression and protein Gene expression and protein
synthesissynthesis Biotechnology toolkitBiotechnology toolkit VirusesViruses
DNA StructureDNA Structure
DNA compositionDNA composition PhosphatePhosphate SugarSugar Nucleic acids (bases)Nucleic acids (bases)
DNA StructureDNA Structure
DNA BackboneDNA Backbone Alternating Alternating
phosphates and phosphates and sugarssugars
Bases are Bases are attached to attached to sugarssugars
DNA StructureDNA Structure DNA is composed of 4 different basesDNA is composed of 4 different bases
Chargraff (1951) data suggested A-T and G-C base pairingChargraff (1951) data suggested A-T and G-C base pairing Pairs are bonded by hydrogen bondsPairs are bonded by hydrogen bonds
DNA ReplicationDNA Replication
Must be completed Must be completed prior to cell divisionprior to cell division
Helicase enzymes Helicase enzymes open the DNAopen the DNA
Polymerase Polymerase enzymes generate enzymes generate a new DNA strand a new DNA strand on each old on each old templatetemplate
TopicsTopics
Discovery of DNA Discovery of DNA DNA structure and replicationDNA structure and replication Gene expression and protein synthesisGene expression and protein synthesis Biotechnology toolkitBiotechnology toolkit VirusesViruses
Gene ExpressionGene Expression
DNA codes for genesDNA codes for genes Genes are expressed as proteinsGenes are expressed as proteins Gene expression is regulatedGene expression is regulated The genome of every cell in your The genome of every cell in your
body is identicalbody is identical Cell type is determined by the genes Cell type is determined by the genes
the cells expressthe cells express
Protein SynthesisProtein Synthesis
DNA DNA →→ RNA RNA →→ Protein Protein TranscriptionTranscription TranslationTranslation
DNA acts as a template for RNA synthesisDNA acts as a template for RNA synthesis RNA has uracil (U) rather than thymine (T)RNA has uracil (U) rather than thymine (T)
Protein synthesis requires 3 types of RNAProtein synthesis requires 3 types of RNA Messenger (mRNA)Messenger (mRNA) Transfer (tRNA)Transfer (tRNA) Ribosomal (rRNA)Ribosomal (rRNA)
Protein SynthesisProtein Synthesis
TranscriptionTranscription mRNA is transcribed from DNA mRNA is transcribed from DNA
Protein SynthesisProtein Synthesis mRNA is read by the synthesis machinerymRNA is read by the synthesis machinery 3 nucleotides make up a codon which 3 nucleotides make up a codon which
codes for 1 of 20 amino acids codes for 1 of 20 amino acids
Protein Protein SynthesisSynthesis
Transfer (tRNA)Transfer (tRNA)
Translates mRNA Translates mRNA sequence into sequence into amino acidsamino acids
80 nucleotide RNA 80 nucleotide RNA moleculemolecule
The anticodon is The anticodon is specific to 1 of 20 specific to 1 of 20 amino acidsamino acids
Protein SynthesisProtein Synthesis Ribosomal (rRNA)Ribosomal (rRNA)
2/3 RNA & 1/3 protein2/3 RNA & 1/3 protein 2 Subunits2 Subunits Coordinates protein synthesisCoordinates protein synthesis
Protein SynthesisProtein Synthesis
The Genetic CodeThe Genetic Code
64 possible codons64 possible codons
1 start codon 1 start codon (AUG)(AUG)
3 stop codons 3 stop codons (UAA, UAG, UGA)(UAA, UAG, UGA)
Protein SynthesisProtein Synthesis
TranslationTranslation InitiationInitiation ElongationElongation TerminationTermination
Protein SynthesisProtein Synthesis
SummarySummary TranscriptionTranscription TranslationTranslation InitiationInitiation ElongationElongation TerminationTermination
Protein SynthesisProtein Synthesis
MutationsMutations Base substitutionBase substitution
ConservativeConservative NonconservativeNonconservative
Insertion/deletionInsertion/deletion Frameshift Frameshift
Jumping genesJumping genes Mobile elementsMobile elements McClintock McClintock
(1940’s)(1940’s)
TopicsTopics
Discovery of DNA Discovery of DNA DNA structure and replicationDNA structure and replication Gene expression and protein Gene expression and protein
synthesissynthesis Biotechnology toolkitBiotechnology toolkit VirusesViruses
Biotechnology ToolkitBiotechnology Toolkit
Isolation of genes for Isolation of genes for studystudy Recombinant DNARecombinant DNA
Gene TherapyGene Therapy Stem cell researchStem cell research CloningCloning
Recombinant DNARecombinant DNA
Isolation of genes for studyIsolation of genes for study Find a gene of interestFind a gene of interest Determine gene sequenceDetermine gene sequence Express the gene productExpress the gene product Functional analysisFunctional analysis
Recombinant DNARecombinant DNA
The ToolsThe Tools
PlasmidsPlasmids Small circular DNA moleculesSmall circular DNA molecules House sequences of interestHouse sequences of interest
BacteriaBacteria Uptake and replicate plasmidsUptake and replicate plasmids Express the gene of interestExpress the gene of interest Good bang for your buckGood bang for your buck
Recombinant DNARecombinant DNA
The MethodThe Method Insert gene of interest into a plasmidInsert gene of interest into a plasmid Bacterial transformation (often Bacterial transformation (often E.coliE.coli)) Plasmid replicationPlasmid replication Gene expressionGene expression Protein purificationProtein purification Protein analysisProtein analysis
Recombinant DNARecombinant DNA
ApplicationsApplications Determine gene functionDetermine gene function Synthesize useful proteinsSynthesize useful proteins
InsulinInsulin Pest resistancePest resistance
DNA mappingDNA mapping Gene TherapyGene Therapy
Gene TherapyGene Therapy
Stem cell researchStem cell research
Embryonic stem cellsEmbryonic stem cells Readily available from fertility banksReadily available from fertility banks Limited government resourcesLimited government resources Ethical concernsEthical concerns Compatibility problemsCompatibility problems
Adult stem cellsAdult stem cells Uses your own stem cellsUses your own stem cells Insufficient technologyInsufficient technology
Gene TherapyGene Therapy
CloningCloning
TherapeuticTherapeutic Recreate specific body partsRecreate specific body parts Too technically challengingToo technically challenging
ReproductiveReproductive Exact replica of an entire organismExact replica of an entire organism First achieved in 1997 with sheepFirst achieved in 1997 with sheep Human success in 2004 but data is Human success in 2004 but data is
questionable questionable
Gene Gene TherapyTherapy
Dolly (1997-2003)Dolly (1997-2003) Scotland 1997Scotland 1997 Nucleus removed Nucleus removed
from unfertilized eggfrom unfertilized egg Nucleus from a sheep Nucleus from a sheep
skin cell insertedskin cell inserted New egg implanted New egg implanted
into surrogate motherinto surrogate mother Died of premature old Died of premature old
ageage
TopicsTopics
Discovery of DNA Discovery of DNA DNA structure and replicationDNA structure and replication Gene expression and protein Gene expression and protein
synthesissynthesis Biotechnology toolkitBiotechnology toolkit VirusesViruses
VirusesViruses
Very simpleVery simple Nonliving organismNonliving organism Uses host to Uses host to
replicatereplicate 2 life cycles2 life cycles
LyticLytic LysogenicLysogenic
TopicsTopics
Discovery of DNA Discovery of DNA DNA structure and replicationDNA structure and replication Gene expression and protein Gene expression and protein
synthesissynthesis Biotechnology toolkitBiotechnology toolkit VirusesViruses