A Recipient Gal^- Bio^- Attl^- Strain of E $\quad \mathrm { gal } ^ { + } \mathrm { bio } ^ { - } \mathrm { attl } ^ { - } \quad 71$

question 51

Multiple Choice

A recipient gal^- bio^- attl^- strain of E. coli is transduced by P1 phage from a donor wild-type gal⁺ bio⁺ attl⁺ strain. (attl^- is a mutant which can't form a l prophage because the site for l integration is missing or defective.) gal⁺ transductants are selected for by plating the recipient cells on a Moderate with galactose as the sole carbon or energy source. Replica plating and testing for lysogenic ability give the complete genotypes of 106 transductants: Class 1: $\quad \mathrm { gal } ^ { + } \mathrm { bio } ^ { - } \mathrm { attl } ^ { - } \quad 71$
Class 2: $\quad \mathrm { gal } ^ { + } \mathrm { bio } ^ { + }attl^-$ $\quad 0$
Class 3: $\quad\mathrm { gal } ^ { + }bio^-$ $a t t l ^ { + } \quad 9$
Class 4: $\quad \mathrm { gal } ^ { + } \mathrm { bio } ^ { + } \mathrm { attl } ^ { + } \quad 26$ What is the frequency of cotransduction between gal and attl?

• A) 33%
• B) 25%
• C) 8.5%
• D) 67%
• E) 46%

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Definitions:

Regio-

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Information about the spatial arrangement of atoms within molecules, important for understanding the behavior and reactivity of different isomers.

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Organic compounds containing a halogen atom replacing a hydrogen atom in an alkyl group.

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