We performed a final experiment where we determined the tightness of DNA packagi

Question

We performed a final experiment where we determined the tightness of DNA packaging for this gene in wild- type toe cells, and in toe cells in which the Talon enhancer had been mutated as described for constructs g-k. In this experiment we isolated chromatin and determined if an enzyme cuts in the gene very well or very poorly, depending on how tightly packed the DNA is at the site of cutting. c. Suggest why the ability of an enzyme to cut chromatin at a specific location might tell us about chromatin structure; specifically packing of DNA (0.5 pt) In this experiment, poor cutting gives a 7kb fragment of DNA, while fragments of 4kb and 3kb indicate good cutting of the DNA. The results are indicated below: Construct DNA fragments observed 4kb, 3kb 7kb, 4kb, 3kb 7kb A,3 Chromatin structure (tight, loose or intermediate) h and j d. Complete the table above to indicate the chromatin structure implied for each construct (4 pts) e. If one of the HRpOgenin or ?ut ogenu transcription factors modifies chromatin structure, whereas the other attracts RNA polymerase II, indicate which factor has which activity. Briefly explain your answer.

Explanation / Answer

c. When DNA is packed tightly at a specific location, this location is not acccessed by cutting enzyme. The location is protected from the activity of the cutting enzymes. For loosely packed DNA the enzymes get access to these sites and thus cut the DNA at these sites. In this way the ability of an enzyme to cut at specific locations tells about the packing of DNA. Easily accessible sites have loose structure while inaccessible sites have tightly packed structure.

d. It is given that poor cutting of the construct by the enzyme gives 7kb fragment while good cutting gives 4kb and 3kb fragments.

For constructs g and k, we get both 4kb and 3kb fragments. This means the sites are easily accessible and there is good cutting by the enzyme. It indicates that the chromatin has a loose packing arrangement.

For construct j , we get only the 7kb fragment. This means that the site is not accessible by the enzyme. It indicates that the chromatin has a tightly packed structure.

For constructs h and i, we get all the three bands i.e 7kb, 4kb and 3kb fragments. This means that the site is not fully but partially accessible to the enzyme. So the site will be partially cut which will give all the three fragments. It indicates that the chromatin has an intermediate packed structure.

Related Questions

Navigate

• Browse (All)
• Browse W
• Subjects

---

---

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