311C F09 Worksheet_12+A

311C F09 Worksheet_12+A - NAME Discussion Worksheet#12 Gene...

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NAME _____________________________ Bio 311C F09 Discussion Worksheet #12 Gene Expression 1. What is gene expression? The process by which DNA directs the synthesis of an RNA or protein product. 2. What is transcription? What is translation? Transcription: synthesis of RNA (any) under the direction of DNA. Translation: synthesis of a polypeptide under the direction of an mRNA. 3. In a eukaryotic cell, where does transcription occur? Translation? Where do these processes occur in a bacterial cell? Eukaryotic: Transcription = nucleus; Translation = cytosol 4. What is a codon? Where do we typically ‘find’ codons? Codon is a three nucleotide sequence (nt triplet) that specifies an amino acid or stop signal; found in mRNA (or DNA) 5. What is a promoter? The DNA sequence that marks where transcription should begin. The site where RNA polymerase will bind (by itself or via transcription factors) to start transcribing. 6. Compare transcription initiation in bacteria and eukaryotes. Bacteria: RNA Pol binds promoter, separates 2 strands of double helix and begins copying. Eukaryotes: Transcription factors bind promoter & allow RNA Pol II to bind. RNA Pol II can then separate the 2 strands & begin copying 7. In which direction does RNA polymerase elongate an mRNA? RNA Pol adds bases only in the 5’ 3’ direction. 8. How does elongation of the polynucleotide differ between DNA replication and transcription? In DNA replication both strands of the parent DNA molecule are copied and the daughter strands stay with the parent template strand. In Transcription only one strand of the parent DNA molecule is copied and the transcript (mRNA) leaves the parent template shortly after being made. 9. How does transcription end in bacteria? In eukaryotes? Bacteria: transcribe terminator sequence, which causes RNA Pol to detach and release completed mRNA. Eukaryotes: transcribe polyadenylation sequence, which causes the pre-mRNA to be cleaved and released from RNA Pol II & the rest of the RNA. RNA Pol II continues transcribing after the pre-mRNA is cleaved. 10.
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This note was uploaded on 12/11/2009 for the course BIO 311 C taught by Professor Mcclelland during the Fall '09 term at University of Texas.

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311C F09 Worksheet_12+A - NAME Discussion Worksheet#12 Gene...

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