A 28-year-old woman comes to the physician because of a 4-day history of lower abdominal pain and pain with urination. A urine sample is collected and sent for culture. Gram-negative bacteria isolated from the urine are found to form pink colonies on lactose-containing MacConkey agar. Several days later, bacterial isolates from a second urine sample are found to form white colonies when plated on the same type of medium. Genetic analysis shows that the more recent isolates have a single nucleotide deletion within the lac operon DNA sequence. This genomic change is most consistent with which of the following?

Question

A 28-year-old woman comes to the physician because of a 4-day history of lower abdominal pain and pain with urination. A urine sample is collected and sent for culture.  Gram-negative bacteria isolated from the urine are found to form pink colonies on lactose-containing MacConkey agar.  Several days later, bacterial isolates from a second urine sample are found to form white colonies when plated on the same type of medium.  Genetic analysis shows that the more recent isolates have a single nucleotide deletion within the lac operon DNA sequence.  This genomic change is most consistent with which of the following?

Quizplus · Accepted Answer

Eductional Objective: A frameshift mutation occurs with the deletion/addition of a number of bases not divisible by 3 in the coding region of a gene.  Frameshift mutations alter the reading frame of the genetic code, dramatically changing the protein structure and often resulting in the formation of a premature stop codon.

A 28-Year-Old Woman Comes to the Physician Because of a 4-Day