Question

Replication can also be carried out by rolling circle replication. Choose the correct statement for this type of replication?

(a) It can be used for the formation of RF

(b) The product of gene III binds on a specific site of double stranded genome

(c) It creates a nick in the – strand generating a free 3’ hydroxyl

(d) This strand is extended by the polymerase and displaces the original – strand

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This interesting question is from BAC Vector, M13 and its Derivatives in portion Other Vector Systems for E of Genetic Engineering

Answer 1

Correct answer is (a) It can be used for the formation of RF

Explanation: Rolling circle replication is used for the formation of RF. The product of gene II binds on a specific site of double stranded genome. It creates a nick in the + strand generating a free 3’ hydroxyl. This strand is extended by the polymerase and it displaces the original + strand. This strand is removed from the newly synthesized strand because of another nick by gene II. Thus a separate + strand is created and it is circularized by gene II product.