Question

Answer the following questions : 

(i) Why is the nutrient medium autoclaved before using it for cell culture? 

(ii) Name the enzyme that can synthesize DNA at a high temperature. 

(iii) Why are restriction enzymes also called as molecular scissors ? 

(iv) Name the nitrogenous bases present in RNA. 

(v) Why is Agrobacterium tumifaciens called as the natural genetic engineer of plants ?

Answer 1

(i) The nutrient medium is autoclaved to make it sterilise i.e., free from microbes. 

(ii) DNA polymerase isolated from a bacterium Thermus aquations.

(iii) Restriction enzymes are called ‘molecular scissors’ because they make cuts at specific positions/recognition sites within both strands of DNA. 

(iv) Adenine, guanine, uracil, cytosine. 

(v) Agrobacterium tumefaciens is able to deliver a piece of DNA known as ‘T-DNA’ to transform normal plant cells into tumour cells. By manipulating its Ti plasmid, it has now been modified into a useful cloning vector for delivering gene of our interest into a variety of plants.