How do enzymes break down nucleic acids

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Nucleases

definition
Nucleases are enzymes that can cleave DNA (DNases) or RNA (RNases). Each cell contains several different nucleases, which can be divided into two broad classes:
Endonucleases: These enzymes cut inside the DNA or RNA strand and break the molecule down into smaller and smaller fragments.
Exonucleases: These enzymes break down DNA from either the 3 'or 5' end of the molecule by removing one nucleotide at a time.
Some nucleases only cleave single-stranded DNA (single-stranded nucleases).

Nucleases have very different functions in the cell. The most important tools of recombinant DNA technology include the restriction endonucleases (which are also among the most well-known nucleases!), Which cleave foreign DNA molecules either unspecifically or in exact sequence and can be viewed as a kind of defense system.

Nonspecific nucleases play a role in digestion, for example, but are also important for the destruction of DNA in programmed cell death (apoptosis), such as DNase I (streptodornase), which occurs in the pancreas, liver, kidneys and platelets.

The stability of the mRNA in the cell nucleus or cytoplasm is also significantly influenced by the presence of RNases. The controlled degradation of mRNA is an important process for the regulation of gene expression in eu- and prokaryotic cells.