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Central Dogma of DNA ANDRES
This document explains the process of protein synthesis, detailing how DNA codes for proteins through the intermediary steps of transcription and translation. It describes the roles of various types of RNA, including messenger RNA, ribosomal RNA, and transfer RNA, as well as the structure of amino acids and the genetic code that translates nucleotide sequences into protein. The document provides a comprehensive overview of how proteins are built from polypeptides and the necessary processes involved in these cellular functions.
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Central Dogma of DNA ANDRES
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- 3. DNADNA • DNA containsgenes, 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. GENES & PROTEINSGENES& PROTEINS Proteins are made of amino acids linked together by peptide bonds 20 different amino acids exist 4
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- 7. DNA BEGINS THEDNABEGINS 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. STARTING WITH DNASTARTINGWITH 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
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- 10. ROLES OF RNAAND DNA •DNA is the MASTER PLAN •RNA is the BLUEPRINT of the Master Plan 10
- 11. RNA DIFFERS FROMDNARNA DIFFERS FROM DNA • RNA has a sugarRNA has a sugar riboseribose DNA has a sugarDNA has a sugar deoxyribosedeoxyribose 11
- 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. STRUCTURE OF RNASTRUCTUREOF RNA 13
- 14. THREE TYPES OFRNATHREE 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. MESSENGER RNA • LongStraight 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. MESSENGER RNA (MRNA)MESSENGERRNA (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. RIBOSOMAL RNA (RRNA)RIBOSOMALRNA (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. 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. THE GENETIC CODE 19 •Usethe code by reading from the center to the outside •Example: AUG codes for Methionine
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- 21. REMEMBER THEREMEMBER THE COMPLEMENTARYBASESCOMPLEMENTARY BASES On DNA: A-T C-G On RNA: A-U C-G 21
- 22. TRANSFER RNA (TRNA)TRANSFERRNA (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. TRANSFER RNATRANSFER RNA 23 aminoacidamino acid attachment siteattachment site U A C anticodonanticodon
- 24. CODONS AND ANTICODONS • The3 bases of an anticodon are complementary to the 3 bases of a codon • Example: Codon ACU Anticodon UGA 24 UGA ACU
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- 26. PATHWAY TO MAKINGPATHWAYTO MAKING A PROTEINA PROTEIN DNADNA mRNAmRNA tRNA (ribosomes)tRNA (ribosomes) ProteinProtein 26
- 27. PROTEINPROTEIN SYNTHESISSYNTHESIS The productionor synthesis of polypeptide chains (proteins) Two phases: Transcription & Translation mRNA must be processed before it leaves the nucleus of eukaryotic cells 27
- 28. DNADNA →→ RNARNA→→ PROTEINPROTEIN 28 Nuclear membrane TranscriptionTranscription RNA ProcessingRNA Processing TranslationTranslation DNA Pre-mRNA mRNA Ribosome Protein EukaryoticEukaryotic CellCell
- 29. TRANSCRIPTIONTRANSCRIPTION •The process ofcopying the sequence of one strand of DNA, the template strand •mRNA copies the template strand •Requires the enzyme RNA Polymerase 29
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- 31. QUESTION:QUESTION: What would betheWhat 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. ANSWER:ANSWER: •DNA 5’-GCGTATG-3’DNA 5’-GCGTATG-3’ •RNA3’-CGCAUAC-5’RNA 3’-CGCAUAC-5’ 32
- 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. TRANSCRIPTIONTRANSCRIPTION • Promoters areregions 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
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- 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. 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. 38CAP TailNew Transcript Result ofTranscriptionResult of Transcription
- 39. MRNA TRANSCRIPT 39 •mRNA leavesthe nucleus through its pores and goes to the ribosomes
- 40. TRANSLATIONTRANSLATION •Translation is theprocess of decoding the mRNA into a polypeptide chain •Ribosomes read mRNA three bases or 1 codon at a time and construct the proteins 40
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- 42. RIBOSOMESRIBOSOMES •Made of alarge and small subunit •Composed of rRNA (40%) and proteins (60%) •Have two sites for tRNA attachment --- P and A 42
- 43. STEP 1- INITIATIONSTEP1- INITIATION • mRNA transcript start codon AUG attaches to the small ribosomal subunit • Small subunit attaches to large ribosomal subunit 43 mRNA transcript
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- 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. INITIATIONINITIATION 46 mRNAmRNA A U GC 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 mRNAmRNA A U GC 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 mRNAmRNA A U GC 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 mRNAmRNA A U GC 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 mRNAmRNA A U GC 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 mRNAmRNA G C UA 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 mRNAmRNA G C UA 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 mRNAmRNA A C AU 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. END PRODUCT –THEENDPRODUCT –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. MESSENGER RNAMESSENGER RNA (MRNA)(MRNA) 55 methionineglycine 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
Editor's Notes
- #14 Like DNA, RNA is a polymer of nucleotides. In an RNA nucleotide, the sugar ribose is attached to a phosphate molecule and to a base, either G, U, A, or C. Notice that in RNA, the base uracil replaces thymine as one of the pyrimidine bases. RNA is single-stranded, whereas DNA is double-stranded.
- #42 Transcription occurs when DNA acts as a template for mRNA synthesis. Translation occurs when the sequence of the mRNA codons determines the sequence of amino acids in a protein.