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Central Dogma of DNA ANDRES

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DNA, protein synthesis, translation, transcription, RNA, codons, Central Dogma of DNA, ANDRES, nucleotides, structure and function, mRNA, tRNA, rRNA, ribosomes, proteins.

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Central Dogma of DNA ANDRES

  1. 1. PROTEINPROTEIN SYNTHESISSYNTHESIS 1
  2. 2. DNADNA ANDAND GENESGENES 2
  3. 3. DNADNA • DNA contains genes, sequences of nucleotide bases • These Genes code for polypeptides (proteins) • Proteins are used to build cells and do much of the work inside cells 3
  4. 4. GENES & PROTEINSGENES & PROTEINS Proteins are made of amino acids linked together by peptide bonds 20 different amino acids exist 4
  5. 5. AMINO ACIDAMINO ACID STRUCTURESTRUCTURE 5
  6. 6. POLYPEPTIDESPOLYPEPTIDES •Amino acid chains are called polypeptides 6
  7. 7. DNA BEGINS THEDNA BEGINS THE PROCESSPROCESS • DNA is found inside the nucleus • Proteins, however, are made in the cytoplasm of cells by organelles called ribosomes • Ribosomes may be free in the cytosol or attached to the surface of rough ER 7
  8. 8. STARTING WITH DNASTARTING WITH DNA • DNA ‘s codeDNA ‘s code must bemust be copiedcopied and taken to the cytosoland taken to the cytosol • In the cytoplasm, thisIn the cytoplasm, this codecode must be readmust be read soso amino acidsamino acids can be assembled to makecan be assembled to make polypeptides (proteins)polypeptides (proteins) • This process is calledThis process is called PROTEIN SYNTHESISPROTEIN SYNTHESIS 8
  9. 9. RNARNA 9
  10. 10. ROLES OF RNA AND DNA •DNA is the MASTER PLAN •RNA is the BLUEPRINT of the Master Plan 10
  11. 11. RNA DIFFERS FROM DNARNA DIFFERS FROM DNA • RNA has a sugarRNA has a sugar riboseribose DNA has a sugarDNA has a sugar deoxyribosedeoxyribose 11
  12. 12. OTHER DIFFERENCESOTHER DIFFERENCES • RNA contains the baseRNA contains the base uracil (Uuracil (U)) DNA hasDNA has thymine (T)thymine (T) • RNA molecule isRNA molecule is single-single- strandedstranded DNA isDNA is double-strandeddouble-stranded 12 DNA
  13. 13. STRUCTURE OF RNASTRUCTURE OF RNA 13
  14. 14. THREE TYPES OF RNATHREE TYPES OF RNA • Messenger RNA (mRNA)Messenger RNA (mRNA) copies DNA’s code & carriescopies DNA’s code & carries the genetic information to the ribosomesthe genetic information to the ribosomes • Ribosomal RNA (rRNA)Ribosomal RNA (rRNA), along with protein, makes up, along with protein, makes up the ribosomesthe ribosomes • Transfer RNA (tRNA)Transfer RNA (tRNA) transfers amino acids to thetransfers amino acids to the ribosomes where proteins are synthesizedribosomes where proteins are synthesized 14 .
  15. 15. MESSENGER RNA • Long Straight chain of Nucleotides • Made in the Nucleus • Copies DNA & leaves through nuclear pores • Contains the Nitrogen Bases A, G, C, U ( no T ) 15
  16. 16. MESSENGER RNA (MRNA)MESSENGER RNA (MRNA) • Carries the information for aCarries the information for a specific proteinspecific protein • Made up ofMade up of 500 to 1000 nucleotides long500 to 1000 nucleotides long • Sequence of 3 bases calledSequence of 3 bases called codoncodon • AUGAUG – methionine or– methionine or start codonstart codon • UAA, UAG, or UGAUAA, UAG, or UGA –– stop codonsstop codons 16
  17. 17. RIBOSOMAL RNA (RRNA)RIBOSOMAL RNA (RRNA) • rRNA is a singlerRNA is a single strandstrand 100 to 3000100 to 3000 nucleotidesnucleotides longlong • GlobularGlobular in shapein shape • Made inside theMade inside the nucleusnucleus of a cellof a cell • Associates withAssociates with proteins to formproteins to form ribosomesribosomes • Site ofSite of proteinprotein SynthesisSynthesis 17
  18. 18. THE GENETIC CODE • A codon designates an amino acid • An amino acid may have more than one codon • There are 20 amino acids, but 64 possible codons • Some codons tell the ribosome to stop translating 18
  19. 19. THE GENETIC CODE 19 •Use the code by reading from the center to the outside •Example: AUG codes for Methionine
  20. 20. NAME THE AMINO ACIDS •GGG? •UCA? •CAU? •GCA? •AAA? 20
  21. 21. REMEMBER THEREMEMBER THE COMPLEMENTARY BASESCOMPLEMENTARY BASES On DNA: A-T C-G On RNA: A-U C-G 21
  22. 22. TRANSFER RNA (TRNA)TRANSFER RNA (TRNA) • Clover-leaf shape • Single stranded molecule with attachment site at one end for an amino acid • Opposite end has three nucleotide bases called the anticodon 22
  23. 23. TRANSFER RNATRANSFER RNA 23 amino acidamino acid attachment siteattachment site U A C anticodonanticodon
  24. 24. CODONS AND ANTICODONS • The 3 bases of an anticodon are complementary to the 3 bases of a codon • Example: Codon ACU Anticodon UGA 24 UGA ACU
  25. 25. TRANSCRIPTIONTRANSCRIPTION ANDAND TRANSLATIONTRANSLATION 25
  26. 26. PATHWAY TO MAKINGPATHWAY TO MAKING A PROTEINA PROTEIN DNADNA mRNAmRNA tRNA (ribosomes)tRNA (ribosomes) ProteinProtein 26
  27. 27. PROTEINPROTEIN SYNTHESISSYNTHESIS The production or synthesis of polypeptide chains (proteins)  Two phases: Transcription & Translation  mRNA must be processed before it leaves the nucleus of eukaryotic cells 27
  28. 28. DNADNA →→ RNARNA →→ PROTEINPROTEIN 28 Nuclear membrane TranscriptionTranscription RNA ProcessingRNA Processing TranslationTranslation DNA Pre-mRNA mRNA Ribosome Protein EukaryoticEukaryotic CellCell
  29. 29. TRANSCRIPTIONTRANSCRIPTION •The process of copying the sequence of one strand of DNA, the template strand •mRNA copies the template strand •Requires the enzyme RNA Polymerase 29
  30. 30. TEMPLATE STRAND 30
  31. 31. QUESTION:QUESTION: What would be theWhat would be the complementary RNA strandcomplementary RNA strand for the following DNAfor the following DNA sequence?sequence? DNA 5’-DNA 5’-GCGTATGGCGTATG-3’-3’ 31
  32. 32. ANSWER:ANSWER: •DNA 5’-GCGTATG-3’DNA 5’-GCGTATG-3’ •RNA 3’-CGCAUAC-5’RNA 3’-CGCAUAC-5’ 32
  33. 33. TRANSCRIPTIONTRANSCRIPTION • During transcription, RNA polymerase binds to DNA and separates the DNA strands • RNA Polymerase then uses one strand of DNA as a template to assemble nucleotides into RNA 33
  34. 34. TRANSCRIPTIONTRANSCRIPTION • Promoters are regions on DNA that show where RNA Polymerase must bind to begin the Transcription of RNA • Called the TATA box • Specific base sequences act as signals to stop • Called the termination signal 34
  35. 35. RNA POLYMERASERNA POLYMERASE 35
  36. 36. MRNA PROCESSINGMRNA PROCESSING • After the DNA is transcribed into RNA, editing must be done to the nucleotide chain to make the RNA functional • Introns, non-functional segments of DNA are snipped out of the chain 36
  37. 37. MRNA EDITINGMRNA EDITING • Exons, segments of DNA that code for proteins, are then rejoined by the enzyme ligase • A guanine triphosphate cap is added to the 5” end of the newly copied mRNA • A poly A tail is added to the 3’ end of the RNA • The newly processed mRNA can then leave the nucleus 37
  38. 38. 38CAP TailNew Transcript Result of TranscriptionResult of Transcription
  39. 39. MRNA TRANSCRIPT 39 •mRNA leaves the nucleus through its pores and goes to the ribosomes
  40. 40. TRANSLATIONTRANSLATION •Translation is the process of decoding the mRNA into a polypeptide chain •Ribosomes read mRNA three bases or 1 codon at a time and construct the proteins 40
  41. 41. 41 TranscriptionTranscription TranslationTranslation
  42. 42. RIBOSOMESRIBOSOMES •Made of a large and small subunit •Composed of rRNA (40%) and proteins (60%) •Have two sites for tRNA attachment --- P and A 42
  43. 43. STEP 1- INITIATIONSTEP 1- INITIATION • mRNA transcript start codon AUG attaches to the small ribosomal subunit • Small subunit attaches to large ribosomal subunit 43 mRNA transcript
  44. 44. RIBOSOMESRIBOSOMES 44 P Site A Site Large subunit Small subunit mRNAmRNA A U G C U A C U U C G
  45. 45. STEP 2 - ELONGATION• As ribosome moves, two tRNA with their amino acids move into site A and P of the ribosome • Peptide bonds join the amino acids 45
  46. 46. INITIATIONINITIATION 46 mRNAmRNA A U G C U A C U U C G 2-tRNA G aa2 A U A 1-tRNA U A C aa1 anticodon hydrogen bonds codon
  47. 47. 47 mRNAmRNA A U G C U A C U U C G 1-tRNA 2-tRNA U A C G aa1 aa2 A U A anticodon hydrogen bonds codon peptide bond 3-tRNA G A A aa3 ElongationElongation
  48. 48. 48 mRNAmRNA A U G C U A C U U C G 1-tRNA 2-tRNA U A C G aa1 aa2 A U A peptide bond 3-tRNA G A A aa3 Ribosomes move over one codon (leaves)
  49. 49. 49 mRNAmRNA A U G C U A C U U C G 2-tRNA G aa1 aa2 A U A peptide bonds 3-tRNA G A A aa3 4-tRNA G C U aa4 A C U
  50. 50. 50 mRNAmRNA A U G C U A C U U C G 2-tRNA G aa1 aa2 A U A peptide bonds 3-tRNA G A A aa3 4-tRNA G C U aa4 A C U (leaves) Ribosomes move over one codon
  51. 51. 51 mRNAmRNA G C U A C U U C G aa1 aa2 A peptide bonds 3-tRNA G A A aa3 4-tRNA G C U aa4 A C U U G A 5-tRNA aa5
  52. 52. 52 mRNAmRNA G C U A C U U C G aa1 aa2 A peptide bonds 3-tRNA G A A aa3 4-tRNA G C U aa4 A C U U G A 5-tRNA aa5 Ribosomes move over one codon
  53. 53. 53 mRNAmRNA A C A U G U aa1 aa2 U primaryprimary structurestructure of a proteinof a protein aa3 200-tRNA aa4 U A G aa5 C U aa200 aa199 terminatorterminator or stopor stop codoncodon TerminationTermination
  54. 54. END PRODUCT –THEEND PRODUCT –THE PROTEIN!PROTEIN!• The end products of protein synthesis is a primary structure of a protein • A sequence of amino acid bonded together by peptide bonds 54 aa1 aa2 aa3 aa4 aa5 aa200 aa199
  55. 55. MESSENGER RNAMESSENGER RNA (MRNA)(MRNA) 55 methionine glycine serine isoleucine glycine alanine stop codon proteinprotein A U G G G C U C C A U C G G C G C A U A AmRNAmRNA start codon Primary structure of a proteinPrimary structure of a protein aa1 aa2 aa3 aa4 aa5 aa6 peptide bonds codon 2 codon 3 codon 4 codon 5 codon 6 codon 7codon 1

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