Test: Tools of Recombinant DNA Technology - NEET MCQ

The molecule which dissolves in water is called hydrophilic molecules. They are polar in nature which helps them in dissolution in water. Being hydrophilic in nature DNA cannot pass through the cell membrane.

Plasmids and bacteriophages can replicate within bacterial cells without the help of chromosomal DNA. Thus they are self-replicating and autonomous in nature. They have their own replication machinery.

The sequence of DNA from where the replication starts is called the origin of replication. It is also written as ‘ori’. It is also responsible for controlling the copy number of target DNA. Bacteria usually have only one origin of replication.

A selectable marker is a gene that helps in identifying successful transformants. They eliminate the growth of non-transformants and favor the growth of the desired organism. It is one of the features which facilitate cloning in a vector.

Genes coding for resistance to antibiotics are usually used as selectable markers. They are introduced in an organism especially bacteria along with plasmid. They help in the identification of transformants.

Transformation is a process in which a foreign DNA is directly picked up by the bacteria from the surrounding environment. It leads to a change in the characteristics of bacteria. It was first observed by Griffith in 1928.

Recognition site is the sequence of DNA where the DNA is cleaved. The presence of more than one recognition site will lead to several cuts within DNA leading to fragmentation of DNA. This will complicate the process of gene cloning.

The Ti plasmid in Agrobacterium tumifaciens leads to tumor formation in dicots. ‘Ti’ stands for tumor-inducing. It may contain more than one T-DNA region. This plasmid is modified and used as a cloning vector.

DNA is an example of a hydrophilic molecule. Hydrophilic molecules are water-loving and tend to dissolve in water easily. They carry a positive or negative charge.

The divalent cations of calcium are used to make cells competent. Calcium is used in the form of a salt of calcium chloride. It increases the efficiency of the bacterial membrane to allow the passage of foreign DNA.

Some bacterial cells have the ability to incorporate foreign DNA within them. These cells are called competent cells. This leads to the alteration of the genetic material of the cell.

The method by which recombinant DNA is directly injected into the nucleus of an animal cell is called micro-injection. A glass micropipette is used for injecting the material into cells.

Biolistics is also known as a gene gun. It is a method in which cells are bombarded with high-velocity micro-particles of gold or tungsten coated with DNA. It is mostly used for plant cells.

42°C-45°C is the ideal temperature for heat-shock treatment. Mostly calcium chloride is used in this. It is suitable for the transformation of bacterial cells such as E.coli.

The microparticles of gold-coated with DNA are used in gene gun technique.  Other metal used for this technique is tungsten.