Question

Question 18 4 pts What role do restriction enzymes play in bacteria? How do bacteria protect their own DNA from the action of restriction enzymes? Change the surface proteins of bacteria; since DNA is not protein, there is no need for protection Cut foreign DNA into pieces; bacteria have RNA genomes. Destroy invading viral DNA: bacterial DNA does not contain the restriction enzyme recognition sequences. Restrict the growth rate of bacteria; bacterial DNA is restriction enzyme resistant.

Answer 1

Restriction enzymes are the bacterial enzymes that can cut DNA at specific sites. They are called restriction enzymes because they restrict the entry of phages into host bacteria. Restriction enzymes have specific recognition sequences with a palindromic arrangement. These are the inverted repeat sequences which means the nucleotide sequences in the 5' to 3' direction is the same in both strands. Hence they cut the foreign DNA into pieces.

The bacterium protects it's own DNA by methylating specific sequence motifs.

enzyme ECORI Methylouse ) 51 Restriction ECORI 3 TTT 31 GTA A TTC Ī Byr 1- 1 . T H K AXG 1 1 1 1 1 151 Fs-2- tare -act A D T T C C 1 T 1 A 1 1 AG 1 1 91 Conesive ends Restriction enzyme X CH₂ с в Атто 5 T I Methylated (CH₂) DNA I TT A A Peotects against self DNA destruction

Bacteria have BOTH DNA as well as RNA genetic material. Methylation is the process by which the bacteria protect their own DNA from the action of own restriction enzymes.