2. From Gene to Protein The connection between genes and proteinsThe connection between genes and proteins The synthesis and processing of RNAThe synthesis and processing of RNA The synthesis of proteinThe synthesis of protein

3. The Connection between Genes and Proteins The study of metabolic defects provided evidence that genes specify proteins One-gene-one- enzyme hypothesis

4. Transcription and Translation: Two Main Processes DNA synthesizes RNA: TranscriptionDNA synthesizes RNA: Transcription RNA synthesizes Protein: TranslationRNA synthesizes Protein: Translation

5. The Genetic Code Triplet sequence of nucleotidesTriplet sequence of nucleotides smallest units of uniform length to allow translation of all 20 amino acidssmallest units of uniform length to allow translation of all 20 amino acids codon- triplet in mRNAcodon- triplet in mRNA

6. Synthesis and Processing of RNA Three types of RNA: mRNA, tRNA, and rRNAThree types of RNA: mRNA, tRNA, and rRNA eukaryotes have three polymeraseseukaryotes have three polymerases RNA polymerase II responsible for mRNA synthesisRNA polymerase II responsible for mRNA synthesis Transcription subdivided into three stages: Initiation, elongation and terminationTranscription subdivided into three stages: Initiation, elongation and termination RNA must be processed before it can functionRNA must be processed before it can function

7. Transcription Initiation: RNA polymerase binds to promoter region,TATA box plays critical role during initiation Initiation: RNA polymerase binds to promoter region,TATA box plays critical role during initiation Elongation: RNA polymerase unwinds DNA and adds nucleotides, 10 bases long, grows 5' to 3' direction.Elongation: RNA polymerase unwinds DNA and adds nucleotides, 10 bases long, grows 5' to 3' direction. Termination: terminator sequence (AAUAAA) stops transcriptionTermination: terminator sequence (AAUAAA) stops transcription DNA reforms double helix, RNA “peals” off template DNA (gene)DNA reforms double helix, RNA “peals” off template DNA (gene)

8. Transcription

9. Transcription Animations http://www.youtube.com/watch? v=-ygpqVr7_xs&feature=relatedhttp://www.youtube.com/watch? v=-ygpqVr7_xs&feature=relatedhttp://www.youtube.com/watch? v=-ygpqVr7_xs&feature=relatedhttp://www.youtube.com/watch? v=-ygpqVr7_xs&feature=related http://www.johnkyrk.com/DNAtra nscription.htmlhttp://www.johnkyrk.com/DNAtra nscription.htmlhttp://www.johnkyrk.com/DNAtra nscription.htmlhttp://www.johnkyrk.com/DNAtra nscription.html http://vcell.ndsu.nodak.edu/anim ations/transcription/movie.htmhttp://vcell.ndsu.nodak.edu/anim ations/transcription/movie.htmhttp://vcell.ndsu.nodak.edu/anim ations/transcription/movie.htmhttp://vcell.ndsu.nodak.edu/anim ations/transcription/movie.htm

10. Post Transcriptional Modification (RNA Processing) Capping: modified GTP added to 5' end of mRNACapping: modified GTP added to 5' end of mRNA Poly (A) tail: 20-200 adenine nucleotides added to 3' end of mRNAPoly (A) tail: 20-200 adenine nucleotides added to 3' end of mRNA RNA splicingRNA splicing

11. Functions of the 5' Cap Protect mRNA from hydrolytic degradationProtect mRNA from hydrolytic degradation Identifies mRNA to the small ribosomal subunitIdentifies mRNA to the small ribosomal subunit

12. Functions of the Poly (A) tail Inhibit degradation if mRNA in the cytosolInhibit degradation if mRNA in the cytosol Facilitate mRNA export from the nucleusFacilitate mRNA export from the nucleus Separated from the stop codon by trailer sequenceSeparated from the stop codon by trailer sequence

13. RNA Splicing Introns: noncoding sequences that are removedIntrons: noncoding sequences that are removed Exons: coding sequences that are spliced togetherExons: coding sequences that are spliced together Small nuclear ribonucleoproteins (snRNPs): identify and help bring about the splicing processSmall nuclear ribonucleoproteins (snRNPs): identify and help bring about the splicing process Spliceosome: catalyzes splicing reactionsSpliceosome: catalyzes splicing reactions

14. RNA Splicing

15. Role of Introns May control gene activityMay control gene activity May allow a single gene to synthesize several different proteinsMay allow a single gene to synthesize several different proteins

16. Translation (The synthesis of proteins) tRNAtRNA RibosomesRibosomes Aminoacyl-tRNA synthasesAminoacyl-tRNA synthases

17. tRNA Interpreter between base sequence of mRNA and amino acid sequence of proteinInterpreter between base sequence of mRNA and amino acid sequence of protein 45 different types45 different types About 80 nucleotides longAbout 80 nucleotides long Anticodon base pairs with codon of mRNAAnticodon base pairs with codon of mRNA

18. Ribosomes Coordinate the pairing of tRNA with mRNACoordinate the pairing of tRNA with mRNA Two subunitsTwo subunits Constructed in the nucleusConstructed in the nucleus Three binding sites: P site, A site and E siteThree binding sites: P site, A site and E site

19. Aminoacyl-tRNA Synthase 20 different types20 different types Two steps:Two steps: 1) activation of amino acid with AMP 1) activation of amino acid with AMP 2) attachment of the amino acid to tRNA

20. Building a polypeptide (Translation) Initiation: brings mRNA, tRNA, and the two ribosomal subunits togetherInitiation: brings mRNA, tRNA, and the two ribosomal subunits together Elongation: three-step cycle that adds amino acids one by one to the initial amino acid, requires cooperation of severalElongation: three-step cycle that adds amino acids one by one to the initial amino acid, requires cooperation of several Termination: release of the polypeptide chain from the complex.Termination: release of the polypeptide chain from the complex.

21. Initiation 5' cap attaches to small ribosome subunit5' cap attaches to small ribosome subunit tRNA carrying methionine attaches to mRNA codontRNA carrying methionine attaches to mRNA codon Large ribosomal subunit attachesLarge ribosomal subunit attaches

22. Elongation Codon recognition: tRNA directed into the A site by an elongation factorCodon recognition: tRNA directed into the A site by an elongation factor Peptide bond forms between adjacent amino acidsPeptide bond forms between adjacent amino acids Translocation: amino acid in the A site is moved to the P siteTranslocation: amino acid in the A site is moved to the P site mRNA moves through the ribosome 5'  3' directionmRNA moves through the ribosome 5'  3' direction

23. Termination Termination sequence is encounteredTermination sequence is encountered Release factor binds to sequenceRelease factor binds to sequence Release factor separates polypeptide and tRNARelease factor separates polypeptide and tRNA

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26. Videos http://vimeo.com/13497169http://vimeo.com/13497169http://vimeo.com/13497169 http://www.dnatube.com/video/5 44/Signal-Recognition-Particle- SRPhttp://www.dnatube.com/video/5 44/Signal-Recognition-Particle- SRPhttp://www.dnatube.com/video/5 44/Signal-Recognition-Particle- SRPhttp://www.dnatube.com/video/5 44/Signal-Recognition-Particle- SRP http://www.wehi.edu.au/educatio n/wehitv/dna_central_dogma_par t_1_-_transcription/http://www.wehi.edu.au/educatio n/wehitv/dna_central_dogma_par t_1_-_transcription/http://www.wehi.edu.au/educatio n/wehitv/dna_central_dogma_par t_1_-_transcription/http://www.wehi.edu.au/educatio n/wehitv/dna_central_dogma_par t_1_-_transcription/ http://www.wehi.edu.au/educatio n/wehitv/dna_central_dogma_par t_2_-_translation/http://www.wehi.edu.au/educatio n/wehitv/dna_central_dogma_par t_2_-_translation/http://www.wehi.edu.au/educatio n/wehitv/dna_central_dogma_par t_2_-_translation/http://www.wehi.edu.au/educatio n/wehitv/dna_central_dogma_par t_2_-_translation/