Within six months of effectively using methicillin to treat S. aureus infections in a community, all new S.aureus infections were caused by MRSA. How can this best be explained?

#Question id: 5760

#XL - R Botany

The fluctuation test of Luria and Delbruck (studying resistance to bacteriophge T1 infection) established that

#Question id: 5761

#XL - S Microbiology

E. coli cells were spread on an agar plate, producing 1000 colonies.  The colonies are replica plated on two agar plates containing the antibiotic kanamycin and one agar plate without antibiotics.  All of the colonies are able to grow on the agar plate without antibiotic but only 4 colonies are able to grow on each of the agar plates containing kanamycin.  You notice that the four colonies that grew on each of the kanamycin containing plates are in the exact same position.  This demonstrates

#Question id: 5762

#XL - S Microbiology

An individual cell homozygous for a mutant allele of the gene for a human enzyme contains no detectable activity for that enzyme. The mutation is best described as

#Question id: 5762

#XL - R Botany

An individual cell homozygous for a mutant allele of the gene for a human enzyme contains no detectable activity for that enzyme. The mutation is best described as

#Question id: 5763

#XL - R Botany

A mutation that causes a mutant phenotype only under restrictive conditions

#Question id: 5764

#XL - R Botany

A wild-type chromosome can be represented as ABC * DEFGH, and from this a chromosomal aberration arises that can be represented AFED * CBGH. This is known as (* = centromere)