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DNA

DNA. [NUCLEIC ACID]. TRANSCRIPTION. RNA. TRANSLATION. PROTEIN. RNA STRUCTURE. 1. RNA CONTAINS RIBOSE, NOT DEOXYRIBOSE, AND THE BACKBONE OF RNA IS RIBONUCLEOTIDES THREE OF THE FOUR BASES IN RNA ARE THE SAME AS IN DNA [ADENINE (A) ; GUANINE (G)

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DNA

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  1. DNA [NUCLEIC ACID] TRANSCRIPTION RNA TRANSLATION PROTEIN

  2. RNA STRUCTURE • 1. RNA CONTAINS RIBOSE, NOT DEOXYRIBOSE, AND • THE BACKBONE OF RNA IS RIBONUCLEOTIDES • THREE OF THE FOUR BASES IN RNA ARE THE • SAME AS IN DNA [ADENINE (A); GUANINE (G) • CYTOSINE (C)]. THE FOURTH BASE IS URIDINE (U)] • RNA MOLECULES ARE SINGLE STRANDED AND START • AT THE 5’ END • THE DIRECTION OF RNA IS 5’ TO 3’ AND THE • NUCLEOTIDES ARE LINKED BY 5’ TO 3’ • PHOSPHODIESTER BONDS JUST LIKE DNA IS.

  3. STRUCTURE OF BASES NOTE THAT U AND T DIFFER BY ONLY A METHYL (CH3) GROUP

  4. NUCLEOTIDE STRUCTURE

  5. 5’ OH OH 3’ PHOSPHODIESTER BOND (RNA) RNAHAS A PHOSPHATE(S) AT THE 5’ END AND AN HYDROXYL (OH) AT THE 3’ END

  6. TRANSCRIPTION: DNA TO RNA • RNA STARTS AT A DEFINED SITE • USUALLY ONLY ONE STRAND OF • THE DNA IS TRANSCRIBED (BUT IT • CAN BE EITHER ONE) • RNA MOLECULES ARE A COPY OF • ONE STRAND OF THE DNA

  7. INFORMATION FOR RNA IN DNA 3’ 5’ 5’ 3’ THE 3 RNAs AT THE TOP HAVE THE SAME SEQUENCE AS THE 5’ TO 3’ STRAND OF DNA AND THE FOUR RNAs ON THE BOTTOM HAVE THE SAME SEQUENCE AS THE 3’ TO 5’ STRAND OF DNA

  8. INITIATION OF TRANSCRIPTION (NO PRIMER IS REQUIRED) pppACGGUACG • 5’ CAGATGCACGGTACG 3’ • 3’ GTCTACGTGCCATGC 5’ • * start site • pppA + pppC = pppApCOH + ppi • pppApCOH + pppG = pppApCpGOH + ppIetc. NOTE: BY CONVENTION THE SEQUENCE OF THE DNA OF A GENE IS THE STRAND WITH THE SAME SEQUENCE AS THE RNA.

  9. SYNTHESIS OF RNA

  10. PROMOTER SEQUENCES HAVE A CONSENSUS E. Coli promoters -35 -10 Consensus sequence TTGACAT- 15-17 nts -TATAAT A/G -35 -10 START SITE +1

  11. GENETIC CODE

  12. TRANSLATION: RNA TO PROTEIN • PROTEIN SEQUENCE (20 AA) IS ENCODED IN THE DNA (4 NTS) BY THE “GENETIC CODE” • THE RIBOSOME, A MACHINE, TRANSLATES THE mRNA AND SYNTHESIZES THE PROTEIN • TRANSFER RNAs (tRNAs) BIND THE AMINO ACIDS AND BRING THEM TO THE RIBOSOME • WHERE THE tRNA HAS A SEQUENCE (ANTICODON) TO DECODE THE GENETIC CODE • CODON.

  13. STRUCTURE OF tRNA DECODES THE mRNA

  14. TRANSLATION P P A A • TWO SITES ON THE • RIBOSOME (P AND A SITE): • ONE HOLDS PEPTIDE AND • THE OTHER THE AMINO ACID • THE PEPTIDE IS TRANSFERRED • TO THE AMINO ACID.

  15. TRANSLATION ELONGATION NNNNNAAAUUUCCGNNNNNN AAA IN THE P SITE BOUND TO LYS-tRNA AND NASCENT PEPTIDE UUU IN THE A SITE ON RIBOSOME IS RECOGNIZED BY THE ANTICODON AAA ON PHENYLALANINE tRNA Lys Phe Pro

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