In recombinant DNA technology antibiotics are used:

1. to keep medium bacteria-free

2. to detect alien DNA

3. to impart disease-resistance to the host plant

4. as selectable markers

Match the following techniques or instruments with their usage:

Select the correct option from the following:

In a mixture, DNA fragments are separated by-

1. Bioprocess engineering

2. Restriction digestion

3. Electrophoresis

4. Polymerase chain reaction

Spooling is:

Select the correct statement from the following:

First discovered restriction endonuclease that always cuts DNA molecules at a particular point by recognizing a specific sequence of six base pairs is:

1. EcoRI

2. Adenosine deaminase

3. Thermostable DNA polymerase

4. Hind II

DNA strands on a gel, stained with ethidium bromide, when viewed under UV radiation, appear as:

During the purification process for recombinant DNA technology, addition of chilled ethanol precipitates out:

Plasmid pBR322 has a PstI restriction enzyme site within gene amp^R that confers ampicillin resistance. If this enzyme is used for inserting a gene for $\mathrm{\beta }$-galactoside production and the recombinant plasmid is inserted in an E.coli strain,

A specific recognition sequence identified by endonucleases to make cuts at specific positions within the DNA is: 

1. Palindromic Nucleotide sequences

2. Poly(A) tail sequences

3. Degenerate primer sequence

4. Okazaki sequences