Question

The structure below shows pUC18, which is similar to pBR322 in its function. However, they differ in some of their restriction sites and the number of ori. The ori number for pBR322 is approximately 20.

1. How are puc18 and pBR322 used in biotechnological studies?
   OR
   What will be the impact if the ori in the above structure gets damaged?
2. The lac z gene has many recognition sites. Study the segment of DNA given below and answer the questions.
   5’... ATC GTA AAG CTT CAT…3’
   3’... TAG CAT TTC GAA GTA…5’
   i) Applying your knowledge of palindrome sequences identify and mark the possible region where the restriction enzyme X will act.
   ii) Restriction enzyme Y was used to extract a gene of interest from a plant. This gene needs to be inserted in the given DNA segment which has been treated with restriction enzyme X. Will there be a successful recombination? Explain with a reason.
3. Which one of the two (pUC18 and pBR322) would you prefer for biotechnological studies? Justify.

Answer 1

1. Plasmids can be used to insert the gene of interest from a desired organism into a host/they act as vectors to transfer the gene of interest into the host.
   OR
   Ori - Origin of replication (ori) - No replication will take place, resulting in no copies of linked DNA.
2. i) 5’... ATC GTA/AAG CTT /CAT…3’
   3’... TAG CAT/TTC GAA /GTA…5’
   OR
   5’... AAG CTT …3’
   3’... TTC GAA …5’ ’
   ii) No, as the restriction enzymes need to be the same which cut the DNA of the plasmid and the gene of interest from the plant.
3. PUC18 as it has a higher copy rate.