Question

Each restriction endonuclease functions by cleaving the:

• A. hydrogen bonds
• B. peptide bonds
• C. phosphodiester bonds
• D. glycosidic bonds

Answer 1

The correct option is C phosphodiester bonds

Restriction enzymes cleave both the DNA strands at specific points by hydrolysing the phosphodiester bond between two nucleotides.

Some restriction enzymes make staggered cuts and produce single-stranded overhangs called sticky ends. These overhangs will easily re-attach to other ends having complementary bases. Thus, they are known as "sticky ends"

Some other restriction endonucleases produce "blunt ends" as they cut DNA strands straight down the middle of a target sequence.


Hydrogen bonds are formed between two DNA strands if the two nitrogenous bases are complementary to each other. Adenine pairs with thymine and guanine pairs with cytosine.
The enzyme helicase breaks the hydrogen bonds between the paired bases and unwinds the DNA double helix.

Glycoside hydrolases catalyse the hydrolysis of glycosidic bonds.

Proteolytic enzymes cleave the peptide bonds.