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Assignment sample solution :. Lecture 5. overview. Generic types of regulation control Regulation of the “sugar” lactose gene(s) for the bactria e. coli [ referred to as the lac operon] Regulation of the expression of the “amino acid” gene tryptophan in E. Coli. [try operon]. Part 1.
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Assignment sample solution: Lecture 5
overview • Generic types of regulation control • Regulation of the “sugar” lactose gene(s) for the bactria e. coli [ referred to as the lac operon] • Regulation of the expression of the “amino acid” gene tryptophan in E. Coli. [try operon]
Part 1 • Two/three elements • What is its overall function defence (… • How the enzyme works (cleaves peptide bonds…) • Abnormal activity: break down connectivity tissue (support structure) in lung…
Part 2: Regulation of Elastase • Brief overview of regulation at transcription level (promoter enhancer/silencer); can also refer to other levels of regulation • The specific regulation of elastase: where/when its transcription occur. • Some elements involved it the expression of the gene. Some reference used by previous , unnamed, students include [1, 2,3,]
Part 3 • Show prokaryotic gene: transcription/transcription example (DNA -> mRNA ->AA) and explain the a contiguous DNA sequence is translated to give, via codons, to give an amino acid strand. • Eukaryotic CDS structure: introns/exons (could also refer to A.S.) • Explain, illustrate, that DNA is first converted into a pre-mRNA and then removal of introns gives an mRNA which is not identical to the DNA and so its translation will not be the same as in prokaryotic regulation
Part 4 • Describe how to find ORF: • Translated DNA sequence over all 6 reading frames (use a diagram or otherwise to illustrate this) • Determine all possible start stop regions. • Look for regions that have a start /stop sequences • Ways to eliminate false positives [4]: • Size of ORF • Proximity of promoter • Bases sequences (specific bp ratios and other sequence structures) • Determine similarity to existing “known” coding sequences
Part 5a code • A script that retrieves a DNA sequence (only) • Translates the sequence into amino acids (single letters and not abbreviations (M not Met) • Repeat the above overall 6 reading frames: • Frames 1 to 3 : • shifting the sequences 1 character and repeating the translation process • Frames 4-6 • get the compliment of the primary stand and revers it; • Repeat the translation process • Search each seq for starts and stops
Part 5b code • Determine the position of the start and stop • Determine the length of sequences where you have a start followed by a stop • Eliminate those whose length is less than 20 • Display the results for all 6 reading frames in a user friendly format.
Reference • [1] Nuchprayoon, I., Simkevich, C. P., Luo, Friedman, A. D. , and M., Rosmarin, A. G., (2012). “GABP Cooperates With c-Myb and C/EBP to Activate the Neutrophil Elastase Promoter”. Blood June 15, 1997 vol. 89 no. 12 4546-4554. • [2] Oelgeschläger, M., Nuchprayoon, I., Lüscher, B., and Friedman, A.D. (1996). “C/EBP, c-Myb, and PU.1 cooperate to regulate the neutrophil elastase promoter”. Mol Cell Biol. 1996 September; 16(9): 4717–4725. • [3] Zimmer, M., Medcalf, R. L, Fink, 1. M., Mattmann, C., Lichter, P., Jenne, D. E. (1992). “Three human elastase-like genes coordinately expressed in the myelomonocytic lineage are organized as a single genetic locus on l9pter”. Proc. No4. Acad. Sci. USA 89, 8215-8219. • Zhang, M.Q. 2002 Computational prediction of eukaryotic coding genes. Nat Rev. Genet. 3 698-709.