Genetic Technology

Free sample questions

Genetic Technology — sample Biology questions with answers

1. Question 1

   What is the main role of restriction enzymes in recombinant DNA technology?

   • ACutting DNA at specific nucleotide sequences
   • BJoining DNA fragments from different sources
   • CCopying DNA in vitro
   • DInserting DNA into a host cell

   Answer: A. Cutting DNA at specific nucleotide sequences

   Restriction enzymes (endonucleases) cut DNA molecules at specific recognition sites, producing fragments with sticky or blunt ends that are essential for the formation of recombinant DNA.

2. Question 2

   What characteristic of plasmids makes them suitable vectors in genetic engineering?

   • ALarge linear DNA molecules
   • BHave one or more restriction enzyme recognition sites
   • CCannot replicate autonomously in bacteria
   • DOnly present in eukaryotic cells

   Answer: B. Have one or more restriction enzyme recognition sites

   Plasmids are small circular DNA molecules that can replicate autonomously in bacteria and have restriction enzyme recognition sites for insertion of foreign genes, as well as marker genes for selection.

3. Question 3

   In the process of forming recombinant DNA, what is the function of DNA ligase?

   • ACutting DNA at specific sequences
   • BJoining DNA fragments by forming phosphodiester bonds
   • CProducing RNA copies from DNA
   • DSeparating the DNA double helix

   Answer: B. Joining DNA fragments by forming phosphodiester bonds

   DNA ligase catalyses the formation of phosphodiester bonds between the $3^{\prime }$ and $5^{\prime }$ ends of DNA fragments, joining the foreign gene with the plasmid vector to form a recombinant DNA molecule.

4. Question 4

   Why are restriction enzymes that produce sticky ends more frequently used compared to blunt ends in recombinant DNA technology?

   • ASticky ends facilitate the process of DNA alignment and ligation
   • BSticky ends prevent the insertion of foreign genes
   • CBlunt ends cannot be joined by DNA ligase
   • DSticky ends are only found in eukaryotic DNA

   Answer: A. Sticky ends facilitate the process of DNA alignment and ligation

   Sticky ends have complementary nucleotide sequences, allowing precise alignment and more efficient ligation by DNA ligase, increasing the success of recombinant DNA formation.

5. Question 5

   What is meant by 'host cell' in genetic engineering?

   • ACell that receives foreign DNA to be replicated and expressed
   • BCell that supplies restriction enzymes
   • CCell used to extract original DNA
   • DCell that produces plasmid vectors

   Answer: A. Cell that receives foreign DNA to be replicated and expressed

   The host cell (usually bacteria such as $Escherichia$ $coli$) receives the recombinant DNA through transformation and then multiplies to produce many copies of the foreign gene or the encoded protein.