Which of the following statements about supercoiling of DNA are true? (1) Supercoiled DNA differs in linking number from relaxed DNA.
(2) Supercoiled DNA can be relaxed through the action of topoisomerases.
(3) All DNA in the cell is positively supercoiled.
(4) A negatively supercoiled DNA is more difficult to unwind.
A) Only 2, and 4 are true
B) Only 1, 2 and re true
C) Only 1 and re true
D) Only 1 and 2 are true
E) All are true

Question

Quizplus · Accepted Answer

Statement 1 is true since supercoiled DNA has a different level of linking number than relaxed DNA. Statement 2 is also true since the process of relaxation of supercoiled DNA involves the action of topoisomerases. Statement 3 is false because not all DNA in the cell is supercoiled, it can be either supercoiled or relaxed. Statement 4 is true since a negatively supercoiled DNA has more twists and turns, making it harder to unwind. Therefore, options A, B, C, and E are incorrect.

Which of the Following Statements About Supercoiling of DNA Are