Biology > EXAM > CHEM180 - Introduction to Biology MID TERM 2 _ All solutions (All)

CHEM180 - Introduction to Biology MID TERM 2 _ All solutions

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1(15 pts.) 1A. Fill in the blanks with the correct word or words below. From p. 143 in the textbook. With such a diverse portfolio of functions, random synthesis of different mRNAs would quickly prov... e disastrous for the cell. Instead, transcription by _RNA polymerase_______ is a tightly regulated event, dependent on the orchestration of __DNA sequences_________and__transcription factors________. Transcriptional regulation is driven by (1) ___growth OR cell division OR reproduction OR development_____ and (2) __metabolism or nutrient intake OR excretion of waste________. 1B. Answer the following question using a short, complete sentence. Under what circumstances can one borrow language from a journal article? The borrowed language must be offset from the main text using quotation marks or indentation, and the source must be cited. 2. (12 pts) Suggest a plausible arrow pushing reaction mechanism for the following reduction of disulfide bonds using a phosphine reagent. Hint: A phosphine (R3P) can act as a nucleophile 3. (30 pts.) 3A. Draw the structure of the peptide QWFLT including correct stereochemistry. NH OHOHO H2NXNXXNXXNXXNX OH HO HO H 2N O OH 3B. On the structure you have drawn above in 3A, place an X over bonds subject to decreased rotational flexibility due to A1,3 strain. 3C. Explain why one bond marked X above is subject to decreased rotational flexibility using a resonance structure if necessary. 3D. Write the sequence for the peptide AsnLeuArgLysSerGlu using one letter abbreviations for each amino acid. NLRKSE 3E. The net charge of the peptide AsnLeuArgLysSerGlu at pH 14 is __-2 (due to deprotonation of N- and C-termini)_______________. 3F. The net charge of the peptide AsnLeuArgLysSerGlu at pH 7 is __+1________________. 3G. The net charge of the peptide AsnLeuArgLysSerGlu at pH 1 is _+3_________________. 3H. What is a DNA sequence capable of encoding the peptide TrpMetPhe? You can omit the ribosome binding site, transcription factor binding sites, and start codon. TGGATGTTC (another possible answer: TGGATGTTT) 3I. What is the sequence of the mRNA encoding TrpMetPhe that is encoded by the DNA sequence you specified in part 3H? UGGAUGUUC OR UGGAUGUUU [Show More]

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