CMMB 511 Lecture Notes - Lecture 3: Community Access Program, Cistron, Exonuclease
28 Dec 2019
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In prokaryotic transcription and translation are intimately related. Rna polymerase binds dna and starts transcribing mrna from 5" -> 3". 2. mrna is translated while being transcribed (nb. mrna is released when transcription is completed) 3. mrna is degraded starting at the 5" end, therefore mrna is unstable. For polycistronic mrnas, translation proceeds sequentially (5" to 3") through cistrons. In eukaryotes, a gene is transcribed to get a monocistronic mrna (in nucleus), which is translated (in cytoplasm) Mrnas capped at 5" and polya tail at 3" to protect mrna from exonuclease activity. Eukaryotic gene expression differs from prokaryotic in 4 significant ways: Eukaryotic dna forms highly ordered chromatin structure (i. e. associated with histone and non-histone proteins) therefore changes in chromatin structure is associated with transcription. Dna transcribed to make primary rna transcript, which is then processed to make mature rna, mature rna moves to cytoplasm to get translated.
