試題詳解

43. Which of the following statements regarding plasmid cloning vectors is     correct    ?

(1) Foreign DNA fragments up to 30,000 base pairs cannot be cloned in a typical plasmid vector. (2) Plasmid vectors must carry promoters for inserted gene fragments.

(3) The copy number of plasmids may vary from a few to several hundred.

(4) In the laboratory, microinjection is commonly used to introduce recombinant plasmids into bacterial cells.

(5) The replication origin (ori sequence) in plasmid cloning vectors is a sequence required for packaging recombinant plasmids into bacteriophage.
(A) 1 and 2.
(B) 3 and 5.
(C) 1, 2, and 4.
(D) 1 and 3.
(E) 3 only.