Match the features that are required to facilitate cloning of alien DNA into a vector.
| List I: Features to facilitate | List II: Cloning Vector |
|---|---|
| A. Origin of replication (ori) | I. Agrobacterium tumefaciens |
| B. Selectable Marker | II. Recognition sites commonly used for restriction enzymes |
| C. Cloning sites. | III. helps in identifying and eliminating non-transformants |
| D. Vectors for cloning genes in plants | IV. sequence from where replication starts |
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → A-IV, B-III, C-II, D-I
(A) Origin of replication (ori) — this matches (IV) sequence from where replication starts. Any DNA linked to the ori is copied along with the vector, and the ori also controls the copy number.
(B) Selectable Marker — this matches (III) helps in identifying and eliminating non-transformants. A marker such as an antibiotic resistance gene lets only transformed cells grow on the selective medium.
(C) Cloning sites. — this matches (II) Recognition sites commonly used for restriction enzymes. The alien DNA is ligated at a restriction site of the vector; a vector should have few such sites, ideally one.
(D) Vectors for cloning genes in plants — this matches (I) Agrobacterium tumefaciens. Its Ti plasmid, made harmless, is used to deliver genes into plants.
NCERT Extract:
Cloning Vectors – “… The following are the features that are required to facilitate cloning into a vector.
(i) Origin of replication (ori) : This is a sequence from where replication starts and any piece of DNA when linked to this sequence can be made to replicate within the host cells. This sequence is also responsible for controlling the copy number of the linked DNA. …
(ii) Selectable marker : In addition to ‘ori’, the vector requires a selectable marker, which helps in identifying and eliminating non-transformants and selectively permitting the growth of the transformants. …
(iii) Cloning sites: In order to link the alien DNA, the vector needs to have very few, preferably single, recognition sites for the commonly used restriction enzymes.”