You want to produce mass amounts of oxytocin, a small peptide hormone produced by the pituitary gland in humans that plays a role in uterine contraction during child birth and lactation during nursing. Your basic approach will be to obtain the gene for oxytocin from the pituitary gland, splice it into a bacterial plasmid, then grow lots of the bacteria to obtain lots of the hormone. For each tool or item listed below, describe what role it plays in the approach you are using to make lots of oxytocin. Bacterial plasmid Restriction enzyme DNA ligasec DNA

Arrange the steps that would be used in a laboratory to engineer a bacterium that could express the human gene coding for factor VIII. Not all steps will be placed. Isolate the human gene that produces factor VIII. Isolate the mRNA of the factor VIII gene. Generate cDNA of the factor VIII gene using reverse transcriptase. Incorrect Insert the factor VIII cDNA into a bacterial vector near a promoter site. Transform the vector into an E. coli bacterium. Human DNA is introduced into the bacterial cell using direct injection by a small needle. E. coli expresses factor VIII. Answer Bank The factor VIII protein is isolated from human tissues.

You plan to synthesize a peptide to be used as a vaccine to treat melanoma, a particularly aggressive form of skin cancer. Normally, gp100, a protein on the surface of melanocytes, activates cell growth when it is bound by its ligand. Activation of the growth pathway depends on the presence of threonine in the ligand. The effective peptide vaccine will mimic the natural ligand, but won’t cause cell growth and division. Below is the sequence of the natural ligand:   LDMKTAG   In order to ensure your newly designed peptide vaccine does not cause cell growth upon binding, you must substitute the Threonine residue at position 5. What amino acid would you replace it with, bearing in mind that the peptide should still be similar enough to bind to the gp100 protein in the surface of melanocytes. Explain your choice. Your vaccine will be administered as a topical cream, and you require your peptide to have an overall neutral charge in order to be functional. At what pH should you formulate…

You are working in the lab and are mutagenizing E. coli, to see if you can identify mutations in the DNA that affect the function of E. coli. Instead of trying to grow the mutants and look for phenotypic defects, you decide to sequence the genome of a few of your mutants. One of the mutant E. coli has a mutation in the gene for tRNA nucleotidyltransferase. Now you decide to try to grow this E. coli mutant in the lab, but you are unable to detect any expansion of the population of bacterial cells. What is a possible mechanistic explanation for the lack of population growth of this mutant E. coli?