Biochemistry 2280A Chapter 7: Topic 20 - Translation
23 Aug 2016
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Describe the steps that occur in the maturation of an rna to form an mrna and allow it to be translated. Bacterial dna is in the cytoplasm which contains the ribosomes on which protein synthesis takes place. During mrna synthesis, ribosomes immediately attach to the free 5" end of rna and begin translating. Transcription takes place in nucleus, protein synthesis on ribosomes in cytoplasm. Rna processing steps (capping, splicing, and polyadenylation) take place as the rna is being synthesized. Enzymes responsible ride on phosphorylated tail of euk rna polymerase ii. 5" 7-methylguanosine rna capping addition of guanine (g) bearing a methyl group at 5" occurs after 25 nucleotides, before whole gene is transcribed. 3" end is trimmed and then finished off by addition of repeated (a) poly-a tail. After capping, and as rna polymerase ii continues to transcribe, introns are removed and exons are stitched.
