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Published byFrancis Bruce Modified over 9 years ago
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Transcription vs Translation
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Central Dogma Transcription Translation
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Chargaff’s Rule States that base ratio is 1:1 A=T CΞGCΞG Therefore if there are 300 Adenines there should also be 300 Thymines in DNA
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Transcription Initiation – RNA polymerase attaches to the promoter region on the DNA and begins to unzip the DNA. Promoter normally contains TATA box, sequence of T-A-T-A
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Transcription Elongation occurs as RNA polymerase unzips the DNA and assembles RNA nucleotides using one strand of the DNA as a template. This occurs in the 5’ 3’ direction
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Transcription Termination occurs when the RNA polymerase reaches a special sequence of nucleotides that servers as a termination point. In eukaryotes the termination region is often AAAAAAAAAAA.
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mRNA processing Before mRNA can leave the nucleus several things happen: 5’ cap is added, cap is guanine nucleotide with 2 extra phosphates Poly A tail added to 3’ end. Tail has about 200 adenine nucleotides. RNA splicing – introns are removed, exons are spliced together. Small nuclear ribonucleoproteins or snRNP’s delete the introns Alternative splicing
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RNA splicing Appropriately joined Protein Introns Exons
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Translation Initiation begins when the small ribosomal subunit attaches near the 5’ end of mRNA A tRNA carrying an amino acid attaches to the mRNA at the start codon AUG. The large ribosomal subunit attaches to the mRNA forming a complete ribosome Elongation begins when the next tRNA binds Translation
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