A 2013 CDC report identified the practice of routinely adding antibiotic compounds to animal feed as a major culprit in the rapid increase in the number of antibiotic-resistant strains. Agricultural practice in recent decades has encouraged the addition of antibiotics to animal feed to promote growth rather than to treat disease.
How might the increase in antibiotic-resistant strains of bacteria in cattle be a threat to human health?

A 2013 CDC report identified the practice of routinely adding antibiotic compounds to animal feed as a major culprit in the rapid increase in the number of antibiotic-resistant strains. Agricultural practice in recent decades has encouraged the addition of antibiotics to animal feed to promote growth rather than to treat disease.

Speculate about the process by which feeding antibiotics to animals such as cattle might lead to an increase in the number of antibiotic-resistant strains of bacteria.

Seven deletion mutations (1 to 7 in the table below) are tested for their ability to form wild-type recombinants with five point mutations (a to e). The symbol "+" indicates that wild-type recombination occurs, and "-" indicates that wild types are not formed. Use the data to construct a genetic map of the order of point mutations, and indicate the segment deleted by each deletion mutation. 

Lateral gene transfer is thought to have played a major role in the evolution of bacterial genomes. Describe the impact of LGT on bacterial genome evolution.

Hfr strains that differ in integrated F factor orientation and site of integration are used to construct consolidated bacterial chromosome maps. The data below show the order of gene transfer for five strains.

Hfr Strain   Order of Gene Transfer (First → Last)

Hfr A        oriT–thr–leu–azi–ton–pro–lac–ade

Hfr B        oriT–mtl–xyl–mal–str–his

Hfr C        oriT–ile–met–thi–thr–leu–azi–ton

Hfr D        oriT–his–trp–gal–ade–lac–pro–ton

Hfr E        oriT–thi–met–ile–mtl–xyl–mal–str

Identify the overlaps between Hfr strains. Identify the orientations of integrated F factors relative to one another.

Hfr strains that differ in integrated F factor orientation and site of integration are used to construct consolidated bacterial chromosome maps. The data below show the order of gene transfer for five strains.

Hfr Strain   Order of Gene Transfer (First → Last)

Hfr A        oriT–thr–leu–azi–ton–pro–lac–ade

Hfr B        oriT–mtl–xyl–mal–str–his

Hfr C        oriT–ile–met–thi–thr–leu–azi–ton

Hfr D        oriT–his–trp–gal–ade–lac–pro–ton

Hfr E        oriT–thi–met–ile–mtl–xyl–mal–str

Draw a consolidated map of the bacterial chromosome. (Hint: Begin by placing the insertion site for Hfr A at the 2 o'clock position and arranging the genes thr–leu–azi- . . . in clockwise order.)

Five Hfr strains from the same bacterial species are analyzed for their ability to transfer genes to F⁻ recipient bacteria. The data shown below list the origin of transfer (oriT) for each strain and give the order of genes, with the first gene on the left and the last gene on the right. Use the data to construct a circular map of the bacterium.

Hfr Strain     Genes Transferred

Hfr 1         oriT met ala lac gal

Hfr 2         oriT met leu thr azi

Hfr 3         oriT gal pro trp azi

Hfr 4         oriT leu met ala lac

Hfr 5         oriT trp azi thr leu met