Which of the following statements are not true regarding restriction endonucleases ?

A. They are called molecular scissors.
B. These are the enzymes responsible for restricting the growth of bacteriophages in E. coli.
C. They cut the DNA only at the centre of the palindromic sites.
D. They remove nucleotides only from the ends of DNA fragments.
E. They recognise specific palindromic base-pair sequences.

Choose the answer from the options given below :

Restriction endonucleases are enzymes that recognize specific short DNA sequences and cleave the DNA at or near those sites.

Statement A: “They are called molecular scissors.”
This is a common nickname because the enzymes cut DNA, so the statement is true.

Statement B: “These are the enzymes responsible for restricting the growth of bacteriophages in E. coli.”
In the bacterial restriction‑modification system, the endonuclease destroys invading phage DNA, thereby limiting phage growth. This statement is true.

Statement C: “They cut the DNA only at the centre of the palindromic sites.”
Many restriction enzymes cut within the palindrome, but many also cut a few nucleotides away from the centre (e.g., producing sticky ends). Therefore the claim that they cut *only* at the centre is false.

Statement D: “They remove nucleotides only from the ends of DNA fragments.”
Restriction enzymes cut *within* the DNA molecule, not merely trimming nucleotides from the ends. Hence this statement is false.

Statement E: “They recognise specific palindromic base‑pair sequences.”
Recognition of short palindromic sequences is a defining feature of restriction endonucleases, so this statement is true.

Consequently, the statements that are not true are C and D only.