Question

Dr. J. Hipsterman has been trying to understand the virulence of the nasty skin pathogen, Iowackius hockious, which causes skin abrasions on humans. Dr. Hipsterman has identified a gene within the I. hockious genome that is predicted to encode a protein on the surface of the bacterium tha breaks down skin tissue. Dr. Hipsterman uses molecular genetics to knocks out this gene, which is called sorE, and then evaluates the importance of sorE for I. hockious virulence using a competition study. The animal model for I. hockious is the chicken-hawk. Dr. Hipsterman applies to the skin of a chicken-hawk a 1:10 mixture of wild type I. hockious relative to mutant I. hockious lacking only the gene sorE (i.e. the bacterial mixture contained 10-times more mutant than wild type). After 24 h, Dr. Hipsterman recovered all the bacteria from the skin of the chicken-hawk, and analysis revealed that there were 5 times more mutant sorE than wild type sorE. From these data alone, what should Dr Hipsterman conclude about the importance of sorE for I. hockious virulence? A. sorE encodes a gene that increases I. hockious virulence B. sorE is not a virulence gene C. sorE encodes a gene that decreases I. hockious virulence D. the competition experiment described here does not address the importance of sorE for I. hockious virulence

Answer 1

Answer: A. sorE encodes a gene that increases I. hockious virulence

Explanation:

Notice that at the start of the study, there were 10 times mutant gene lacking sorE compared to the wild type. After 24 hours, it reduced to 5 times compared to the wild type, this is an indication that sorE is a virulence gene and it's absence reduces the virulence of the bacteria.