THE JOHNS HOPKINS UNIVERSITY KRIEGER SCHOOL OF ARTS AND SCIENCES MASTER OF SCIENCE IN BIOTECHNOLOGY Course Title: Molecular Biology Course Number: 410.602.84 Spring, 2014 Rajavel-Problem Set 3 You must work independently. Follow the honor code. You must reference the source to support your response. Assignment is due by Apr 10. Total points: 20 1. Trp operon: Suppose you delete the ribosome binding site for the gene that codes for the leader peptide, or insert a few bases between the leader peptide gene and sequence 2, what effects would these have on E.coli trp operon? 2. The following codes for DNA sequence: Using the codon table (check your textbook), indicate the effects on the resultant protein 5’ TTTGCCACG 3’ a. G substituted for C in position 5 b. A substituted for G in position 9 c. An insertion of A between 6th and 7th position d. A deletion of T at position 3 3. Consider a negatively controlled operon with two structural genes (A and B, for enzymes A and B), an operator site (O), and a regulatory (repressor) gene (R). A wild type (WT) haploid strain (all the above are functional) produces basal enzyme levels in the absence of the inducer and produces increased (induced) enzyme levels in the presence of the inducer. Indicate the results of gene expression (compared to WT) for A and B in the following mutant strains in the absence and presence of the inducer: ` a. A strain that has a defective repressor (R-) b. A strain that has a defective Operator (Oc) Note:(Oc) refers to a mutated operator site with more than a single base change 4. A protein contains five consecutive leucine zipper pseudorepeats. This protein forms a dimer upon binding of the subunits’ respective leucine zipper domains. Assuming each leucine zipper domain consists of just one helix, how many turns does the helix