Wild type E. coli metabolizes the sugar lactose by expressing the enzyme ß-galactosidase. You have isolated a mutant that you call lac1–, which cannot synthesize ß-galactosidase and cannot grow on lactose (Lac–). During an condition you have a wild type (Lac+) strain carrying a Tn5 insertion known to be near several Lac genes on the E. coli chromosome. You grow P1 phage on this strain and use the resulting phage lysate to infect the lac1– strain, selecting for kanamycin resistance (Kanr). Among 100 Kanr transductants, you find that 82 are Lac– and 18 are Lac+. Express the distance between Tn5 and the lac1– mutation as a cotransduction frequency;

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#Question id: 19119

#Unit 8. Inheritance Biology

You are conducting genetic linkage studies of an autosomal recessive disease whose chromosomal location has not been firmly established. You are focused on two SSR markers that may be linked to each other and to the disease. Here are two families in which some individuals are affected:

                     

Calculate LOD scores for linkage at θ= 0.02 between SSR42 and SSR43 in Family 2.

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#Question id: 4656

#Unit 11. Evolution and Behavior

Logically, which of these should cast the most doubt on the relationships depicted by an evolutionary tree?

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#Question id: 114

#Unit 1. Molecules and their Interaction Relevant to Biology

Sphingosine is not a component of

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#Question id: 4376

#Unit 3. Fundamental Processes

Which of the following is the correct order of binding of general transcription factors to initiate transcription at RNA polymerase II promoters?

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#Question id: 2007

#Unit 4. Cell Communication and Cell Signaling

In which of the cases could the mother exhibit an anti-Rh-factor reaction to the developing fetus?