1
Question
Restriction endonucleases are
Restriction endonucleases are
Open in App
Solution
The correct option is A Synthesised by bacteria for their defence
Definition of restriction endonuclease
Restriction endonucleases are the enzymes which cleave the DNA by digesting phosphodiester bonds at the specific sequences within the DNA. Examples include EcoR I.
Restriction modification system
Restriction modification system is a defence mechanism in bacteria, which is used against bacteriophages. It consists of two enzymes that work in the following manner:
● Restriction enzyme : They restrict the propagation of foreign DNA in the bacterium.
● Modification enzyme : They add methyl groups to one or more bases within the recognition sequence of restriction enzymes. The DNA with the modified sequences cannot be recognised and cut by restriction enzymes.
DNA ligase
DNA ligases are enzymes that catalyse the formation of phosphodiester bonds between two DNA fragments, helping in uniting two DNA molecules.
DNA polymerase
DNA polymerases are the enzymes that can add nucleotides to an already existing DNA strand or primer. Hence DNA polymerases are used for in vitro DNA synthesis.
DNase
Deoxyribonuclease (DNase) is the enzyme that digests DNA and plays a part in removal of DNA in dead cells.
Final answer
(D) Synthesised by bacteria for their defence
Definition of restriction endonuclease
Restriction endonucleases are the enzymes which cleave the DNA by digesting phosphodiester bonds at the specific sequences within the DNA. Examples include EcoR I.
Restriction modification system
Restriction modification system is a defence mechanism in bacteria, which is used against bacteriophages. It consists of two enzymes that work in the following manner:
● Restriction enzyme : They restrict the propagation of foreign DNA in the bacterium.
● Modification enzyme : They add methyl groups to one or more bases within the recognition sequence of restriction enzymes. The DNA with the modified sequences cannot be recognised and cut by restriction enzymes.
DNA ligase
DNA ligases are enzymes that catalyse the formation of phosphodiester bonds between two DNA fragments, helping in uniting two DNA molecules.
DNA polymerase
DNA polymerases are the enzymes that can add nucleotides to an already existing DNA strand or primer. Hence DNA polymerases are used for in vitro DNA synthesis.
DNase
Deoxyribonuclease (DNase) is the enzyme that digests DNA and plays a part in removal of DNA in dead cells.
Final answer
(D) Synthesised by bacteria for their defence
Suggest Corrections
0
Similar questions
View More
Join BYJU'S Learning Program
Explore more
Join BYJU'S Learning Program
