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Week 8: Gene Regulation

You’ve transformed Agrobacterium tumefaciens with a modified Ti plasmid.  Within the T-DNA boundaries, the plasmid carries no gall-inducing genes but DOES contain a general plant promoter upstream of a gene of interest that you’d like to transfer to the plant.  What would you expect to happen if these engineered Agrobacteria were placed on a plant at the site of a wound? 

The presence of ____ in an E. coli cell induces CAP at the CAP binding site and activates transcription of the lac operon resulting in _____ of lacZ expression.

Complete the table using you knowledge of transcription, translation, and the codon table below. For each blank typ three capital letters. Codon 1 Codon 2 Codon 3 DNA-Non-template Strand (5′-3′) ATG CAG TAC DNA-Template Strand (3′-5′) [blank1] [blank5] [blank9] mRNA (5′-3′) [blank2] [blank6] [blank10] tRNA (3′-5′) [blank3] [blank7] [blank11] Amino Acid (3-letter) [blank4] [blank8] [blank12]      

Short Answer A. (5 pts) Many people say that sexual reproduction is beneficial because it produces variation.  Based on our conversation in class, explain why it is more nuanced than that.  When is creating variation through sexual reproduction beneficial,  when is it costly, and why?

cDNAs are often considered desirable for molecular biologists because cDNAs match the primary transcript AND. . .

Which is a required component (i.e. more than a helpful feature) of plasmids we use to carry a gene within a bacterial cell for the purpose of cloning it?

The synthesis of a polypeptide occurs primarily during which stage of translation?

At the end of meiosis I. . . (Choose the best answer)

Operon Mutants. Scientists have isolated a variety of different mutations which affect E. coli’s ability to effectively metabolize lactose.  Record the effect of each of the following mutations in order to complete the table.   # Description Result 1 lacI gene mutated so that lacI protein is not produced. (e.g. a Mutation in the lacI promoter) [blank1] 2 lacP promoter is mutated so that RNA polymerase cannot bind. [blank2] 3 Lactose permease is not produced due to a mutated ATG start codon in the lacY gene. [blank3] 4 lacI gene mutated such that the repressor is produced but that it cannot bind to the operator. (e.g. a mutation in the DNA binding region) [blank4] 5 A mutation in the lacI promoter which vastly increases the amount of repressor that is present. [blank5] 6 lac operator is mutated so that it can no longer bind to the repressor. [blank6]