How Cells Read The Genome From Dna To Protein

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How Cells Read the Genome: From Deoxyribonucleic acid to Poly peptide PowerPoint Presentation

How Cells Read the Genome: From Deoxyribonucleic acid to Protein

How Cells Read the Genome: From DNA to Protein. Affiliate half-dozen. How Cells Read the Genome. Transcription Translation Folding of Proteins Evolution of the "Central Dogma". How Cells Read the Genome. The Genomes of Multicellular Organisms: a State of Disarray! Introns

Updated on Mar 21, 2019

• rna
• rna politician
• rna polymerase
• pre mrna
• rna pol tail
• rna pol ii continues

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How Cells Read the Genome: From DNA to Protein

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1. How Cells Read the Genome: From Dna to Poly peptide Chapter 6

2. How Cells Read the Genome • Transcription • Translation • Folding of Proteins • Evolution of the "Key Dogma"

3. How Cells Read the Genome The Genomes of Multicellular Organisms: a State of Disarray! • Introns • Irregularities in Gene Density • Little organization relating to gene office • Adjacent genes often prove no relatedness

4. How the Cells Read the Genome The "Cardinal Dogma" Deoxyribonucleic acid RNA Poly peptide Variations in the Fundamental Dogma RNA Splicing RNA as the final gene production

5. Transcription RNA vs Deoxyribonucleic acid • Ribose every bit opposed to deoxribose sugar • Single stranded • Uracil in place of Thymine • RNA molecules west/ structural and catalytic properties

6. Transcription General Features of Transcription • Produces RNA using one strand of DNA equally template molecule • Merely modest portion of Deoxyribonucleic acid is transcribed • Begins w/unwinding of sm portion of Deoxyribonucleic acid exposing bases • Transcript elongated past complementary base pairing by RNA polymerase • RNA transcript shorter than DNA

7. Transcription RNA Polymerase • Transcribes DNA by catalyzing the formation phosphodiester bond btwn nucleotides • Moves along DNA unwinding DNA simply ahead of agile site • Extends chain in the 5' to 3' management • Hydrolysis of high-free energy bonds provides energy • Many copies of RNA from same factor in small amount of time

8. Transcription RNA Polymerase vs Deoxyribonucleic acid Polymerse • RNA Polymerase catalyzes improver of ribonucleotides • Can begin RNA synthesis without primer • Not as accurate as DNA Polymerse; RNA Polymerase 1 error/104 nucleotides vs 1 fault/107 nucleotides • Both have proof reading capability

9. Transcription Different Types of RNA • mRNA; RNA copied from genes that ultimately directly synthesis of proteins (3-5% total RNA) • Concluding product of minority of genes is RNA itself: tRNA, rRNA, snRNA (majority of total RNA) • Tens of thousands of different mRNA transcripts; ten-15 copies of ea species/jail cell

10. Transcription in Procaryotes Beginning and Stop Signals embedded in DNA • Promoter= DNA sequence RNA Polymerase binds to initiate RNA synthesis • RNA Polymerase's sigma subunit (bact) binds to promoter & opens helix • Ane of exposed strands serves as template • Afterward synthsis of ~10 bases sigma subunit of RNA Polymerase disassociates • RNA Polymerase undergoes structural changes moving forward apace synthesizing RNA at ~50 bp/sec • RNA Polymerase continues until termination signal of string of A-T preceded by "hairpin loop" • Termination signal causes RNA Politician to disassociates from RNA releasing Dna • Gratuitous RNA Polym complexes once over again w/ sigma subunit

11. Transcription in Procaryotes

12. Transcription Transcription Promoter and Terminator Signals • Heterogeneous but incorporate related consensus sequence recognized by sigma subunit of RNA Politician • Precise promoter sequence governs analogousness for RNA Pol = "strength" • Can exist predicted by algorithms but need to be independently verified • Promoters are assymetric; RNA Pol can demark in one orientation and extend in 5' to 3' management only • Terminators more heterogeneous than promoters; ability of RNA to fold into "hairpin loop" is most of import characteristic

13. Transcription in Eucaryotes 3 Types of RNA Polymerases of similar in structure in Eucryotes • RNA Pol I- transcribes tRNA, rRNA, smRNAs • RNA Politico II- transcribes genes encoding proteins • RNA Pol III- transcribes tRNA, rRNA, smRNAs

14. Transcription Transcription in Eukaryotes vs Procaryotes • Nucleosomes and higher lodge chromatin packaging • RNA Pol requires Full general Transcription Factors

15. Transcription Full general Transcription Factors (Eukaryotes) • Assemble at promoters of all RNA Pol Two transcripts • Facilitate binding of RNA Politician 2 • Help in opening DNA strands for transcription to brainstorm • Release RNA Political leader from promoter into elongation mode once transcription has begun

16. Transcription v unlike General Transcription Factors

17. Transcription Other Proteins Required past RNA Political leader in Eucaryotes • Transcriptional activators- bind to specific sequences and facilitate binding of GTFs and RNA Pol • Mediators- enable activators to interact westward/ GTFs and RNA Politician • Chromatin Remodeling Complexes- let greater accessibility to Dna • Many proteins required to initiate transcription, > 100 subunits

18. Transcription Elongation • Elongation factors= ensures that RNA Politician does not disassociate before end of gene; assoc. due west/ RNA Pol shortly after initiation of transcription • Dna topoisomerases removes superhelical tension • Dna gyrases uses ATP to pump supercoils into Dna • Elongation tightly coupled to RNA processing

19. Transcription RNA Processing • Eucaryotic mRNA capped at five' end • polyadenylated at 3' end • Introns removed Phosphorylation of RNA tail CTD • consists of domain of repeated 52 times of 7 aa containing 2 serines that are phosphorylated • phosphorylation of tail promotes disassoc of RNA Political leader from proteins presents at start of transcription • allows new set of proteins that function in elongation and pre-mRNA processeing, to assoc

20. Transcription Capping of Pre-mRNAs • Capping of 5' terminate w/ modified guanine nucleotide occurs after ~25 bases synthesized • 3 enzymes involved in capping procedure 1. phosphatase removes ane P' from v' end of RNA 2. guanyl transferase adds GMP to 5' end 3. methyl transferase adds methyl grp to guanosine • Capping enzymes demark to phosphorylated tail of RNA Pol • Cap binds CBC (cap binding complex) that facilitates RNA processing and export

21. Transcription General Features of RNA Splicing • Involves two transesterification reactions to bring together exons and remove intron in form of lariat • v boosted RNAs, > 50 proteins, and lots of ATP required • Complication ensures accurateness • Alternative splicing occurs in 60% of human genes • Increase coding potential and facilitates evol of new protein sequences

22. Transcription Sequences Marker Where Splicing Occurs • Intron size varies from x-100,000 nucleotides • 3 conserved nucleotide sequences 5' splice site 3' splice site branch points that forms base of operations of excised lariat

23. Transcription Spliceosome Mediates Splicing of RNA • performed primarily past five snRNA molec (U1, U2, U4, U5) forming spliceosome core • snRNA molec recognize intron-exon borders and participate in splicing chemistry • Spliceosome circuitous of RNA and protein • More fifty proteins invovled

24. Transcription Mechanism of RNA Slicing 1. spliceosome recognizes splicing signals on pre-mRNA, brings ends of intron together 2. co-operative point site recognized by BBP and U2AF 3. U2 snRNP displaces BBP base of operations pairing westward/ branch point consensus seq 4. U1 snRNP base of operations pairs w/ 5' splice site junction 5. U4/U6•U5 triple snRNP enters half-dozen. RNA-RNA rearrangements disrupts U4/U6 base of operations pairing to enable U6 to displace U1 at 5' splice junction; U4 exits 7. U2 and U6 snRNPs in spliceosome form 3d RNA structure bringing 5' junction into position near co-operative chain A for first esterification

25. Transcription Mechanism of RNA Slicing viii. 5' and 3' junctions brought together via U5 snRNP for second esterification ix. snRNPs remain jump to lariat while splice production released

26. Transcription Spliceosome and ATP Hydrolysis • Not required for splicing chemistry • Needed for associates and rearrangements • RNA helicase requiring ATP needed to pause RNA-RNA interactions • All steps except assoc of BBP w/ co-operative chain A, and U2 w/ 5' splice site require ATP and other proteins • Removal of snRNP from lariat requires RNA-RNA interactions that are dependent on ATP hydrolysis

27. Transcription Assembly of Spliceosome • Occurs every bit pre-mRNA emerges from transcribing RNA Pol • Components of the spliceosome are carried on RNA Pol tail and transferred to nascent pre-mRNA • Exon size tend to be compatible ~150 bp • Spliceosome assembly occurs co-transcriptionally, splicing sometimes occurs postal service-transcriptionally • Spliceosome proteins SR (rich in Ser and Arg) assemble on exon and mark off 3' and 5' site starting at v' cease of mRNA, associates occurs in conjunction w/ U1 snRNA and U2AF

28. Transcription Plasticity of RNA Splicing • Splicing mech selected for flexibility • Flexibility enables cell to regulate blueprint of RNA splicing • Alternative splicing when diff proteins tin can be made from same gene • Splicing patters regulated so unequal forms of protein produced at unequal times and in unequal tissues

29. Transcription Cocky-Splicing Introns • Group I Intron= reactive Grand nucleotide attacks the initial phosphdiester bound cleaved during the spicing rxn • Group Two Intron= reactive A in intron seq is attaching grp, and lariat intermediate generated • Sequence of cocky=splicing introns is critical; RNA folds in specific 3d conformation that brings 5' and three' junctions together and provides precisiely positioned reactive grps to perform chemical science • Pre-mRNA splicing mech evolved from Grp 2 Splicing spliceosomal snRNPs took over structural and chemical roles of Grp Ii Introns so sequence constraints no longer needed

30. Transcription Group I Introns Group II Introns

31. Transcription Processing of 3' End of pre-mRNA • Termination signs are transcribed into RNA and recognized proteins as RNA Pol transcribes thru them • CstF (cleavage stimulating factor F) and CPSF (cleavage and processing specificity gene) proteins assoc w/ RNA Pol tail transferred to RNA as it emerges

32. Transcription Processing the 3' End of the Pre-mRNA • Additional proteins assemble w/ CstF and CPSF to perform processing: ane. RNA is cleaved 2. Poly-A-Polymerase adds ~200 A's to 3' end of cleaved product 3. RNA Politico Ii continues to transcribe after pre- mRNA has been cleaved; several 100 bases earlier falls off template and transcription terminates 4. RNA downstream of cleavage is degraded

33. Transcription Selective Export of Mature mRNAs from Nucleus How does cell distinguish btwn rate mature mRNA and debris from mRNA processing? • Consign highly selected and coupled to correct mRNA processing • mRNA exported but if appr prepare of proteins are leap including: ane) cap bounden circuitous 2) snRNP proteins absent 3) proteins that mark complete splicing Selective Consign of Mature mRNAs from Nucleus

34. Transcription hnRNPs= heterogeneous nuclear ribonuclear proteins, near arable proteins that assemble on pre-mRNA as it emerges from RNA Pol • Some hnRNPs remove hairpin helices from RNA so that splicing and other signals on RNA can be read • hnRNPs excluded from exons, remain on excised introns marking them for nuclear retentiveness and/or destruction • Some reamin bound to fully processed mRNA and accompany them to cytoplasm

35. Transcription Most of the RNA in the Cell Performs a Catalytic or Structural Function • ~80% of full RNA is rRNA • three-5% of full RNA mRNA • rRNA transcribed by RNA Pol I (which has no C-terminal tail) • rRNA is neither capped or polyadenylated • RNA components of ribosome are final cistron products; growing cell syn ~10 million of ea blazon of rRNA ea cell generation

36. Transcription rRNA Genes • Mammalian cells comprise 10 million ribosomes • Multi-re-create genes E. coli has 7 copies of its rRNA Humans ~200 copies on 5 chromosomes Xenopus ~600 copies single cluster on 1 chromosome • iv types of eucaryotic rRNAs ea present in 1 copy/ribosome 18S, five.8S and 28S encoded past unmarried lg precursor RNA-chemically modified 5S rRNA syn from separate cluster by Pol III- not chemically modified

37. Transcription Chemic Modification of Lg rRNA Precursor • 100 methylations of two'-OH • 100 isomerizations of uridines • Function of chem. modification unknwn but may facilitate folding or assembly • snoRNAs= small nucleolar RNAs guide in chemic modification and cleavage of precursor rRNA • snoRNAs encoded in introns, esp those of ribosomal proteins, function in nucleolus

38. Transcription Nucleolus as a Ribosome Producing Mill • site for processing rRNAs and associates into ribosomes • lg aggregate of macromolecules including: rRNA genes, precursor rRNAs, mature rRNAs, rRNA processing enzymes, snoRNPs, ribosomal protein subunits, and some partially assembled ribosomes • Size varies and reflects number of ribosomes jail cell is making; may occupy 25% of nuclear vol • Also site where other RNAs produced and other RNA-poly peptide complexes assembled (tRNAs, snoRNAs, U6 snRNP, telomerase)

39. Translation From RNA to Protein • Genetic code dictates how mRNA translated into aa sequence of protein • Nucleotides read consecutively in grps of three (condons) • Degenerate genetic code; 64 codons specify xx aa • 6 possible reading frames

40. Translation tRNA as an Adaptor Molecule • Recognizes and binds to codon and appr. aa • ~lxxx nucleotdies • Folds into clover leafage and and then into Fifty-shaped structure • Ii regions of unpaired nucelotdies at ends of Fifty shaped molecule essential to part ane. anticodon= fix of iii consecutive nucleotides pairs westward/complementary codon on mRNA 2. short ss region near three'end where aa attaches

41. Translation Redundancy/Degeneracy of Genetic Code • More 1 tRNA for many of the aa • Some tRNAs base pair west/ more than one aa; Wobble Position

42. Translation tRNAs • Number and kinds of tRNAs varies beyond species ie: humans have 497 tRNA genes w/ merely 48 unequal anticodons represented • Transcribed by RNA Pol Iii • Some transcripts are spliced via cutting-and-paste mechanism catalyzed past proteins (no lariat) occurs when tRNA is properly folded in cloverleaf conf • Extensive modifications > 50 dissimilar kinds • 1 modification/10 nucleotides • Modifications essential to: 1) accuracy of tRNA attaching to right aa ii) recognition of mRNA codon by tRNA anticodon

43. Translation Aminoacyl-tRNA Synthetases • Couple aa to appr fix of tRNAs • Aa specific • Enzymatic reaction attaches aa to 3' end of tRNA requires ATP • High energy bond produced btwn aa and tRNA later used to covalently link aa to growing polypeptide chain

44. Translation • Editing past tRNA synthetases • Selects correct aa in two step procedure: 1. right aa highest affinity for active site 2. aa forced into second pocket whose dimensions exclude correct aa • Those that enter second editing site are hydrolyzed from AMP- hydrolytic editing • Raises overall accuracy of tRNA charging to one mistake/40,000 couplings • Synthetase must as well recognize right tRNAs

45. Translation Ribosome Structure: rRNA molecules + l dissimilar proteins

46. Translation Ribosome Structure and Role • Large and Small Subunits; rRNA sequence highly conserved • 66% RNA; 33% protein • rRNA responsible for: structure positioning tRNAs on mRNA catalytic activity in forming peptide bond

47. Translation mRNA Decoded on Ribosomes • Ribosomal subunits assemble on mRNA well-nigh 5' cease • Ribosome translates mRNA in aa sequence using tRNAs every bit adaptors to add aa in right sequence to end of growing polypeptide chain • aa linked by peptide bail germination • 2 aa added/sec eucaryotic cell; 20 aa/sec added by bact • 4 impt ribosomal binding sites

48. Translation Major Steps in Translation • Ribosomal Assembly and Initaition • Elongation • Termination and Release of Nascent Polypeptide

49. Translation Ribosomal Associates • Initiation tRNA-Met & eIFs demark sm rRNA subunit • Sm rRNA subunit binds to v' end of mRNA recognizing CAP and 2 eIFs (eucaryotes) • Sm rRNA scans for AUG start • eIFs dissociate and lg rRNA binds • Initiator tRNA-met at present in P-site leaving A-site vacant for incoming aminoacyl rRNA to beginning poly peptide synthesis

50. Translation Procaryotes take Shine Delgarno Sequence • Specific sequence few nucleotides upstream of AUG commencement • AGGAGGU • Bounden site positions sm rRNA subunit at AUG start • Bacterial mRNAs can exist poly-cistronic; eucaryotes monocistronic

Source: https://www.slideserve.com/elan/how-cells-read-the-genome-from-dna-to-protein-powerpoint-ppt-presentation

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