$3$(a) Development of recombinant DNA technology has opened gates to many breakthroughs in the fields of medicine and agriculture. This has enabled scientists to isolate, sequence and manipulate individual genes obtained from diverse living or dead cells. Given below is a diagram showing the basic steps involved in genetically modifying an organism. Study the given diagram and answer the questions that follow : 2022_CBSE_Biology_Set_Region2_Subset_Set1_Q13_SECTION-C__p6_9

2022_CBSE_Biology_Set_Region2_Subset_Set1_Q13_SECTION-C__p6_9

(i)Are two different types of restriction endonucleases used, one to cut the vector DNA and another to cut the desired DNA to be cloned ? Support your answer, giving reason.(ii)Which enzyme is used at step (X) to integrate the foreign DNA with the vector DNA ?(iii)What is the term used for step (Y) showing multiple copies of the foreign DNA being formed in transformed E. coli ?(iv)Draw a diagram of E. coli cloning vector pBR322 to show the following :

(I) Any one restriction endonuclease site in tetracycline resistance gene (II) Any one restriction endonuclease site in ampicillin resistance gene (III) 'ori' site (v) What does "rop" code for in plasmid pBR322 ? (b) RNA interference (RNAi) holds great potential as a therapeutic agent for the treatment of human diseases and as a bicontrol agent for controlling pests in the agricultural fields. An experiment was conducted to study the use of'RNAi'for the potential treatment of disorders of cholesterol metabolism. Some people possess genetic mutations with elevated levels of'ApoB'gene which predisposes them to coronary artery diseases. Lowering the amount of'ApoB'can reduce the number of lipoproteins and lower the blood cholesterol. Tracy Zimmerman and her colleagues used RNAi in 2006 to reduce the level of'ApoB'in non-human primates Cynomolgus monkeys. (i) One group of monkeys were given RNAi treatment (Small interfering RNAs, SiRNAs) (doses $\displaystyle 1 \mathrm{mg} / \mathrm{kg}$ SiRNAs) , (ii) Second group of monkeys were given RNAi treatment (doses $\displaystyle 2.5 \mathrm{mg} / \mathrm{kg}$ SiRNAs) , and (iii) Third group of monkeys were injected saline as control. The results of the experiments are illustrated in the graph given below: 2022_CBSE_Biology_Set_Region2_Subset_Set1_QUNKNOWN__i_p7_18

2022_CBSE_Biology_Set_Region2_Subset_Set1_QUNKNOWN__i_p7_18

(i)What do you interpret from the bars (X and Z) obtained after 264 hours of treatment of monkeys with saline and $\displaystyle 2 \cdot 5 \mathrm{mg} / \mathrm{kg}$ SiRNAs treatment?(ii)Name the category of organisms in the living world, where RNA interference (RNAi) takes place. Why?(iii)What is the basic principle involved in RNA interference (RNAi) in silencing the preferred genes?

Biology · Biotechnology and its Applications