Question

You have a DNA sequence of 1600 bp. To characterize it, you decide to make a restriction map. Cutting with the first enzyme, you show by electrophoresis that the fragments produced are 400 and 1200 bp respectively. After using the second enzyme, you recover 700-bp and 900-bp fragments. After treatment with both enzymes, fragments were 300, 400, and 900 bp. Which is the correct map?

You have a DNA sequence of 1600 bp. To characterize it, you decide to make a restriction map. Cutting with the first enzyme, you show by electrophoresis that the fragments produced are 400 and 1200 bp respectively. After using the second enzyme, you recover 700-bp and 900-bp fragments. After treatment with both enzymes, fragments were 300, 400, and 900 bp. Which is the correct map?

A. -400/--900-----/300 ---
B. -300-/--400--/--900----
C. -400-/300-/---900-----
D. -400-/-100/--300--/900
E. -900 ------/400--/3---

Answer 1

C. -400-/300-/---900-----

Step-by-step explanation:

You have two restriction enzymes (let's call them A and B) capable of cutting double stranded DNA.

The full DNA fragment is 1600 bp long:

----------------------1600----------------------

After digestion with enzyme A, you get two fragments of 400 and 1200 bp.

The most probable location of a single restriction site for enzyme A is:

--------------A------------------------------------

400 1200

After digestion with enzyme B, you get two fragments of 700 and 900 bp.

The most probable location of a single restriction site for enzyme B is:

-----------------------B---------------------------

700 900

Digestion with both restriction enzymes yields three fragments of 300, 400 and 900 bp:

--------------A--------B---------------------------

400 300 900