It Has Been Found That a Particular "+ -" Combination

question 45

Essay

It has been found that a particular "+ -" combination of frameshift mutations in gene X gives a wild-type phenotype,whereas a "- +" combination gives a mutant phenotype,even though the sites of insertion/deletion are the same.How might these results be explained?

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Definitions:

Menarche

The occurrence of the first menstrual cycle in adolescent females, a key event in female puberty.

Ortho Evra

A type of birth control patch applied to the skin that releases hormones to prevent pregnancy.

Brevicon

A type of combined oral contraceptive pill that contains low doses of synthetic estrogen and progestin.

Ogen

A brand name for estropipate, a form of estrogen used in hormone therapy.