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Biotechnology: Principles and Processes — BIOLOGY STD 12 Science — Question

Gujarat BoardEnglish MediumSTD 12 ScienceBIOLOGYBiotechnology: Principles and Processes1 Mark
Question
Two statements are given-one labelled Assertion and the other labelled Reason. Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below.
  1. Both assertion and reason are true and reason is the correct explanation of assertion.
  2. Both assertion and reason are true but reason is not the correct explanation of assertion.
  3. Assertion is true but reason is false.
  4. Both assertion and reason are false.
Assertion: Restriction enzymes cut the strand of DNA to produce sticky ends or blunt ends.
Reason: Stickiness of the ends facilitates the action of the enzyme DNA polymerase.
✓

Answer

  1. Assertion is true but reason is false.

Explanation:

Restriction enzyme, a type of endonuclease, functions by "inspecting" the length of a DNA sequence. Once it finds a recognition sequence, it binds and cut each of the two strands of the double helix at specific point a staggered cut generates two sticky ends and a straight cut generates blunt end. The staggered cut leaving single stranded portions at the ends which results in overhanging stretches called sticky ends. These are named so because they form hydrogen bonds with their complementary counter parts, i.e., they can join similar complementary ends of DNA fragment from some other source with the help of DNA ligase. This stickiness of the ends facilitates the action of the enzyme DNA ligase, not DNA polymerase.

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