In a cotransformation experiment DNA was isolated from a donor strain that was proA+ and strC+ and sensitive to tetracycline. (The proA and strC genes confer the ability to synthesize proline and confer streptomycin resistance, respectively.) A recipient strain is proA− and strC− and isresistant to tetracycline. After transformation, the bacteria werefirst streaked on a medium containing proline, streptomycin, andtetracycline. Colonies were then restreaked on a medium containingstreptomycin and tetracycline. (Note: Each type of medium hadcarbon and nitrogen sources for growth.) The following resultswere obtained:70 colonies grew on the medium containing proline, streptomycin,and tetracycline, but only 2 of these 70 colonies grew whenrestreaked on the medium containing streptomycin and tetracyclinebut lacking proline.What would you expect the cotransformation frequency to be ifthe average size of the DNA fragments was 4 minutes and thetwo genes were 1.4 minutes apart?
In a cotransformation experiment DNA was isolated from a donor strain that was proA+ and strC+ and sensitive to tetracycline. (The proA and strC genes confer the ability to synthesize proline and confer streptomycin resistance, respectively.) A recipient strain is proA− and strC− and is
resistant to tetracycline. After transformation, the bacteria were
first streaked on a medium containing proline, streptomycin, and
tetracycline. Colonies were then restreaked on a medium containing
streptomycin and tetracycline. (Note: Each type of medium had
carbon and nitrogen sources for growth.) The following results
were obtained:
70 colonies grew on the medium containing proline, streptomycin,
and tetracycline, but only 2 of these 70 colonies grew when
restreaked on the medium containing streptomycin and tetracycline
but lacking proline.
What would you expect the cotransformation frequency to be if
the average size of the DNA fragments was 4 minutes and the
two genes were 1.4 minutes apart?
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