Test: Biotechnology: Principles & Processes - 1 - NEET MCQ

• Plasmids renature because they have supercoiled structures that have held the two strands of the helix together during denaturation.
• Chromosomal DNA is not able to renature, however, because its longer strands have become mixed with denatured proteins.

• Insertional inactivation is the inactivation of a gene upon insertion of another gene inside in its place or within its coding sequence.
• It help in identification of recombinant clones.

Line in NCERT: "The presence of insert results into insertional inactivation of the β-galactosidase gene and the colonies do not produce any colour, these are identified as recombinant colonies."

• Having two antibiotic resistance genes in the same plasmid helps in identifying transformants.
• Transformants take up the plasmid and also integrate it into recombinant DNA.

Line in NCERT: "The ampicillin resistance gene in this case is called a selectable marker."

• In order to use the DNA for genetic engineering processes, it must be in pure form, free from other macromolecules.
• This is termed DNA isolation and is the pioneer step. Since the DNA is enclosed within the membranes, it is required to break open the cell to release DNA along with other macromolecules such as RNA, proteins, polysaccharides, lipids, etc. and from this mixture, DNA is purified.
• A release of DNA from a cell is achieved by treating the cells or tissues with enzymes such as lysozyme (bacteria), cellulose (plant cells), chitinase (fungus), etc.
• These enzymes degrade cell wall; plasma membrane degrading enzymes like lipase, etc., are also needed. Since yeast is a fungus and fungal cell wall is made of chitin (fungal cellulose), isolation of DNA necessarily requires the use of enzyme chitinase.

Line in NCERT: "chitinase (fungus)."

• The polymerase chain reaction is a technology in molecular biology used to amplify a single copy or a few copies of a piece of DNA.
• Calcium ions is not required in PCR technology.

Line in NCERT: Not Found

In agarose gel electrophoresis, the DNA fragments separate out (resolve) according to their size or length because of the sieving property of agarose gel. It means, the smaller the fragment size, the farther it will move.

Line in NCERT: "The DNA fragments separate (resolve) according to their size through sieving effect provided by the agarose gel."

Restriction enzymes are also called 'molecular scissors' as they cleave DNA at or near specific recognition sequences known as restriction sites. These enzymes make one incision on each of the two strands of DNA and are also called restriction endonucleases.

Line in NCERT: "Restriction enzymes belong to a larger class of enzymes called nucleases."

• All the enzymes at higher temperature become inactive.
• Denaturation is done at high temperature as it leads to breaking down of hydrogen bonds between the bases of polynucleotides.

Line in NCERT: "Denaturation; (ii) Primer annealing; and (iii) Extension of primers"

• Origin of replication is the specific DNA sequence on chromosome that which is responsible for initiating replication.
• Origin of replication is essential for replication of particular DNA segment.

Line in NCERT: "In a chromosome there is a specific DNA sequence called the origin of replication, which is responsible for initiating replication."

The groups of letters that form same words when read both forward and backward are called Palindrome. For example MALYALAM which read same from both side.

Line in NCERT: "Do you know what palindromes are? These are groups of letters that form the same words when read both forward and backward, e.g., 'MALAYALAM'."

The Enzymes used to join foreign DNA to plasmid is ligases. The plasmid of bacteria replicate this DNA strands along with other which can be further transferred to target cells.

Line in NCERT: "these can be joined together (end-to-end) using DNA ligases."

The separated DNA fragments can he visualised only after staining the DNA with a compound known as ethidium bromide followed by exposure to ultraviolet radiation (we cannot see pure DNA fragments in the visible light and without staining).

Line in NCERT: "The separated DNA fragments can be visualised only after staining the DNA with a compound known as ethidium bromide followed by exposure to UV radiation (you cannot see pure DNA fragments in the visible light and without staining)."

EcoRI comes from Escherichia coli RY 13. In EcoRI, the letter ‘R’ is derived from the name of strain.

Line in NCERT: "In EcoRI, the letter 'R' is derived from the name of strain."

The separated DNA fragments can be visualized only after staining the DNA with a compound known as ethidium bromide followed by exposure to UV radiation. We can see bright orange coloured bands of DNA in aethidium bromide stained gel exposed to UV light.

Line in NCERT: "The separated DNA fragments can be visualised only after staining the DNA with a compound known as ethidium bromide followed by exposure to UV radiation (you cannot see pure DNA fragments in the visible light and without staining). You can see bright orange coloured bands of DNA in an ethidium bromide stained gel exposed to UV light."

• In gel electrophoresis, DNA molecules moves towards positively charged anode because DNA is negatively charged molecules.
• The molecules separate out due to difference in molecular weight.

Line in NCERT: "DNA is a negatively charged molecule, hence it moves towards the positive electrode (anode)"

• Rop genes in pBR322 codes for protein involved in replication of plasmid.
• Plasmid are able to take the foreign gene and to be transferred to target cells.

Line in NCERT: "rop codes for the proteins involved in the replication of the plasmid."

DNA is coated with tungsten before used in biolistic gun for inserting the DNA directly into target cells for obtaining particular protein.

• Bioreactors are used to obtain biological products on large scale continually for commercial purpose.
• The sparged stirred tank bioreactor is advantageous over the simple stirred tank bioreactor as air bubbles enhance the oxygen transfer area.

Line in NCERT: "Bubbles dramatically increase the oxygen transfer area."

• Blades in a bioreactor help in mixing of all the components and prevent their settling at the bottom of reactor tank.
• It also increases the oxygen level in bioreactor.

Line in NCERT: "A stirred-tank reactor is usually cylindrical or with a curved base to facilitate the mixing of the reactor contents. The stirrer facilitates even mixing and oxygen availability throughout the bioreactor."

• A ladder is used in Gel electrophoresis as it helps in comparing the size of the DNA fragment.
• The fragments get separated from each other on the basis of molecular weight of the fragments.

Line in NCERT: "The DNA fragments separate (resolve) according to their size through sieving effect provided by the agarose gel."