Which of the following statements are not true regarding restriction endonucleases? Choose the answer from the options given below :
- C and D only
- A and E only
- D and E only
- A and B only
Answer
(1) C and D only
Solution
A, B and E are true: restriction endonucleases are molecular scissors, they restrict phage growth in E. coli and they recognise specific palindromic sequences.
C is false: they usually cut a little away from the centre of the palindrome, leaving sticky ends.
D is false: removing nucleotides from the ends is done by exonucleases; endonucleases cut inside the DNA.
Not true: C and D only.
Answer: (1)