question_answer 31)

  Which of the following statements does not hold true for restriction enzyme? (a) It recognizes a palindromic nucleotidesequence (b) It is an endonuclease (c) It is isolated from viruses (d) It produces the same kind of sticky ends in different DNA molecules

Answer:

                  (c) The restriction enzymes are called 'molecular scissors' and are responsible for cutting DNA on specific sites. These are not found in viruses. They are present in bacteria to provide a type of defense mechanism called the' restriction modification system' and the so called system consist of two component restriction enzymes and modification enzyme. The first component include restriction endonudease, which identify the introduced foreign DNA and cut it into process. Same kind of sticky end in different individual molecule of DNA are also produced by these molecular scissors special sequence inthe ONA recognized by restriction endonudease is called palindromic nucleotidesequence.