BMEN 289 hw 8 answers

BMEN 289 hw 8 answers - 2. a.) There are 3 cis-acting...

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
Nicole Girsch November 1, 2007 BMEN 289: HW #8 1. a.) The termination of transcription occurs when the polymerase encounters a termination signal causing the transcription to stop, releasing the RNA from the polymerase, and dissociating the enzyme from its DNA template. b.) The pre-RNA has an attachment sight for a stretch of adenine nucleotides called the poly (A) tail. This special attachment site is where the transcript is cut, and the poly (A) tail is attached to the exposed 3’ end, completing the mRNA molecule, which is ready for export into the cytoplasm. c.) The 5’ end of the transcript is modified by adding a 7-methylguanosine cap, which stabilizes the RNA and aligns eukaryotic mRNAs on the ribosome during translation. The 3’ end undergoes polyadenylation, which results in the termination of transcription. The poly-A tails have been shown to regulate both translation and mRNA stability, and this also plays a role in early development, where changes in the length of poly-A tails control mRNA translation.
Background image of page 1
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: 2. a.) There are 3 cis-acting elements. b.) The first cis-acting element is located (i.)315 base pairs of DNA upstream of the initiation site, the trans-acting element that bind to it is (ii.) an enhancer, and (iii.) it is not regulated by shear stress. The second element is located (i.) 116 base pairs upstream, the trans-acting element that binds to it is (ii.) an enhancer, and it (iii.) is regulated by shear stress. The third cis-acting element is located (i.) near the initiation site, the trans-acting element that binds to it is (ii.) an enhancer, and (iii.) it is partially regulated by shear stress 3. a.) Since glucose levels are low, levels of cAMP are elevated, which stimulates the binding of CAP regulatory protein to the sequence. Also, since lactose levels are low, the lac repressor will also be bound. b.) There will be no mRNA transcription, and therefore no expression of LacZ....
View Full Document

This note was uploaded on 04/07/2008 for the course BMEN 289 taught by Professor Kaunas during the Fall '07 term at Texas A&M.

Ask a homework question - tutors are online