CBSE Questions for Class 12 Medical Biology Biotechnology: Principles And Processes Quiz 2 - MCQExams.com

• Restriction endonuclease enzyme is known as the molecular scissor because a restriction enzyme recognizes and cuts the DNA only at a particular sequence of nucleotides and producing smaller fragments. 
• Helicases are enzymes that bind and may even remodel nucleic acid or nucleic acid-protein complexes. There are DNA and RNA helicases are involved in the unwinding of the nucleic acids. 
• In molecular biology, DNA ligase is a specific type of enzyme that facilitates the joining of DNA strands together by catalyzing the formation of a phosphodiester bond. 
• The DNA polymerases are enzymes that create DNA molecules by assembling nucleotides, the building blocks of DNA. 

• r-DNA technology is the process involving the introduction of a foreign piece of DNA containing a gene of interest into the genome of an organism.
• Isolation and separation are the steps in the process in which various techniques are used to separate the required gene (containing the gene of interest) from the nucleus of the cell (free of the other cellular contaminants).
• The isolated DNA is then restriction digested and amplified to make several copies. 
• It is then inserted into a vector for transfer into an appropriate host. 
• Elution is a step involved in the process of the separation of DNA. 

• Recombinant DNA technology enables individual fragments of DNA from any genome to be inserted into vector DNA molecules, such as plasmids. 
• The plasmids are used to transfer this rDNA into the host cell where multiple copies of the DNA fragments can be amplified (multiplied).
• Each amplified fragment is called a DNA clone and the process of producing multiple copies of desired DNA sequence through rDNA technology is gene cloning.
  

• Gel electrophoresis is a technique commonly used in laboratories to separate charged molecules like DNA, RNA, and proteins according to their size.
• In gel electrophoresis, the molecules to be separated are pushed by an electrical field through a gel that contains small pores.
  
• DNA fragments are negatively charged, so they move towards the positive electrode after applying the electric field.
  
• Small size molecules can move faster through these pores than larger molecules.

Correct Option: A

Explanation:

• A retroviral vector is made up of proviral sequences that may accept the desired gene, allowing both to be incorporated into the target cells.
• The vector also includes viral and cellular gene promoters, such as the CMV promoter, to boost gene expression in the target cells.
• Retroviruses function differently - their RNA is reverse-transcribed into DNA, which is integrated into the host cell's genome, and then undergoes the usual transcription and translational processes to express the genes carried by the virus.
  

Thus, Retrovirus is used as a vector for cloning of genes into higher organisms.

• A gene gun is a system in which a particle is used to inject the genetic material directly into the cell. 
• This method is known as biolistic particle delivery system which was originally designed for plant transformation. 
• A metal particle is coated with the genetic material and transferred into the host cells to allow the foreign DNA to get incorporated into the host's genome. 

• The polymerase chain reaction is a biochemical technology. 
• It is used to amplify or to increase the number of a single copy of DNA with high accuracy and speed.
• During this process, the Taq polymerase enzyme polymerizes the new DNA strand by using single-stranded DNA as a template.

Agrobacterium tumefaciens is a bacterial plant pathogen found in the soil which causes crown gall disease in plants. The basic mechanism that works behind it is the transfer of a segment or small piece of bacterial DNA to the plant genome. This bacterial DNA segment gets incorporated into the plant genome, stabilizes there and transcribes or expresses itself. The bacterial DNA causing disease is situated on a plasmid, Ti plasmid (Tumour inducing plasmid, 200kb) instead of on a bacterial chromosome. 

In dsDNA, the sequence of nucleotides in one chain is same as in the opposite chain, is called palindromic sequence and the region with palindromic sequence is called palindrome.

In one chain of DNA GAATTC is present in 5’ to 3’ direction, same sequence is found in opposite chain.

so, the correct option is 5’GAATTC 3’