In the following palindromic base sequences of DNA, which one can be cut easily by a particular restriction enzyme? [2022]
5′ G A T A C T 3′ ; 3′ C T A T G A 5′
5′ G A A T T C 3′ ; 3′ C T T A A G 5′
5′ C T C A G T 3′ ; 3′ G A G T C A 5′
5′ G T A T T C 3′ ; 3′ C A T A A G 5′
Given below are two statements: [2022]
Statement I: Restriction endonucleases recognise specific sequence to cut DNA known as palindromic nucleotide sequence.
Statement II: Restriction endonucleases cut the DNA strand a little away from the centre of the palindromic site.
In the light of the above statements, choose the most appropriate answer from the options given below:
Both Statement I and Statement II are correct.
Both Statement I and Statement II are incorrect.
Statement I is correct but Statement II is incorrect.
Statement I is incorrect but Statement II is correct.
Which of the following is not a desirable feature of a cloning vector? [2022]
Presence of origin of replication
Presence of a marker gene
Presence of single restriction enzyme site
Presence of two or more recognition sites
(4)
In order to link alien DNA, the vector needs to have preferable single recognition site for commonly used restriction enzyme. Presence of more than one recognition sites within vector will generate several fragments and will complicate the gene cloning.
DNA strands on a gel stained with ethidium bromide when viewed under UV radiation, appear as [2021]
bright blue bands
yellow bands
bright orange bands
dark red bands
(3)
In the process of gel electrophoresis, the separated DNA fragments can be seen after staining the DNA with a compound like ethidium bromide (EtBr) followed by exposure to UV radiation as bright orange coloured bands.
Plasmid pBR322 has PstI restriction enzyme site within gene that confers ampicillin resistance. If this enzyme is used for inserting a gene for -galactoside production and the recombinant plasmid is inserted in an E. coli strain. [2021]
It will be able to produce a novel protein with dual ability.
It will not be able to confer ampicillin resistance to the host cell.
The transformed cells will have the ability to resist ampicillin as well as produce -galactoside.
It will lead to lysis of host cell.
A specific recognition sequence identified by endonucleases to make cuts at specific positions within the DNA is [2021]
poly (A) tail sequences
degenerate primer sequence
okazaki sequences
palindromic nucleotide sequences
(4)
A restriction endonuclease recognises a specific palindromic nucleotide sequence to make a cut at specific position within the DNA.
Identify the wrong statement with regard to restriction enzymes. [2020]
Each restriction enzyme functions by inspecting the length of a DNA sequence.
They cut the strand of DNA at palindromic sites.
They are useful in genetic engineering.
Sticky ends can be joined by using DNA ligases.
Choose the correct pair from the following. [2020]
Ligases - Join the two DNA molecules
Polymerases - Break the DNA into fragments
Nucleases - Separate the two strands of DNA
Exonucleases - Make cuts at specific positions within DNA
The specific palindromic sequence which is recognised by EcoRI is [2020]
5′ - GAATTC - 3′ ; 3′ - CTTAAG - 5′
5′ - GGAACC - 3′ ; 3′ - CCTTGG - 5′
5′ - CTTAAG - 3′ ; 3′ - GAATTC - 5′
5′ - GGATCC - 3′ ; 3′ - CCTAGG - 5′
(1)
The palindromes in DNA are base pair sequences that are same when read forward (left to right) or backward (right to left) from a central axis of symmetry.
Thus, is a palindromic sequence which is recognised by EcoRI.
The sequence that controls the copy number of the linked DNA in the vector, is termed [2020]
selectable marker
Ori site
palindromic sequence
recognition site
(2)
Ori site is a sequence from where replication starts and any piece of DNA when linked to this sequence can be made to replicate within the host cells. This sequence is also responsible for controlling the copy number of the linked DNA in the vector. So, if one wants to recover many copies of the target DNA it should be cloned in a vector whose origin support high copy number.
