To test whether the mutation in the LEF1 binding site in DNA is sufficient to ch

Question

To test whether the mutation in the LEF1 binding site in DNA is sufficient to change LEF1 gene expression, the investigators measured transcription of a “reporter” gene (a gene whose protein product is easy to assay in the laboratory) in cells. Expression of the reporter gene is controlled by 7 repeated copies of the optimal LEF sequence, 7 copies of the LEF1 binding sequence from dark-haired individuals, or 7 copies of the LEF1 binding sequence from blond individuals (see part A of figure below). Transcription of the reporter gene was measured in cells with increasing amounts of expressed LEF1 protein. The fold increase in reporter protein activity is plotted as a function of LEF1 protein expression in B.

Which line above do you think represents the sequence associated with blond hair?

Question 4 options:

closed circles

open circles

closed triangles

insufficient information

A)

closed circles

B)

open circles

C)

closed triangles

D)

insufficient information

7 tandem LEF 1 binding sites 25 15 10 Encodes LEF1 responsive reporter protein (easily assayed) LEF1 responsive reporter gene promoter (replaces gene X normally expressed when LEF1 binds to its binding site) Amount of LEF1 protein expressed in cell

Explanation / Answer

The line with closed triangles represents the sequence associated with blond hair.

It is known that blond individuals have defective LEF1 binding site, which does not bind LEF1 properly. Therefore, these individuals would not be able to express an LEF1-responsive reporter protein even when high quantities of LEF1 are present. This state of non-responsiveness is correctly represented by the line with the closed triangles.

Related Questions

Navigate

• Browse (All)
• Browse T
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.