12. a. You want to create a genetic construct that will express GFP in Drosophila. In addition to the GFPcoding sequence, what DNA element(s) must youinclude in order to express this protein in flies if theconstruct were integrated into the Drosophila genome? Where should such DNA element(s) be located? How would you ensure that GFP is expressedonly in certain tissues of the fly, such as the wing?b. Suppose you insert the GFP coding region plus allof the DNA elements required by the answer to part(a)—except the enhancer—between inverted repeatsfound at the ends of a particular transposable element.Because all of the DNA sequences located betweenthese inverted repeats can move from place to placein the Drosophila genome, you can generate manydifferent fly strains, each with the construct integrated at a different genomic location. You now examine animals from each strain for GFPfluorescence. Animals from different strains showdifferent patterns: some glow green in the eyes,others in legs, some show no green fluorescence,etc. Explain these results and describe a potentialuse for this experiment.13. In Problem 12, you identified a genomic region thatis likely to behave as an eye-specific enhancer. Whatexperiments could you perform to verify that theseDNA sequences indeed share all the characteristics ofan enhancer and to determine the precise boundariesof the enhancer in the genomic DNA?

12. a. You want to create a genetic construct that will express GFP in Drosophila. In addition to the GFP
coding sequence, what DNA element(s) must you
include in order to express this protein in flies if the
construct were integrated into the Drosophila genome? Where should such DNA element(s) be located? How would you ensure that GFP is expressed
only in certain tissues of the fly, such as the wing?
b. Suppose you insert the GFP coding region plus all
of the DNA elements required by the answer to part
(a)—except the enhancer—between inverted repeats
found at the ends of a particular transposable element.
Because all of the DNA sequences located between
these inverted repeats can move from place to place
in the Drosophila genome, you can generate many
different fly strains, each with the construct integrated at a different genomic location. You now examine animals from each strain for GFP
fluorescence. Animals from different strains show
different patterns: some glow green in the eyes,
others in legs, some show no green fluorescence,
etc. Explain these results and describe a potential
use for this experiment.
13. In Problem 12, you identified a genomic region that
is likely to behave as an eye-specific enhancer. What
experiments could you perform to verify that these
DNA sequences indeed share all the characteristics of
an enhancer and to determine the precise boundaries
of the enhancer in the genomic DNA?