Final answer:
Bacteria have evolved mechanisms like restriction endonucleases and the CRISPR-Cas system to defend against viruses by recognizing and digesting invading DNA. Transformation allows them to take up environmental DNA, leading to genetic diversity and the potential acquisition of advantageous traits.
Step-by-step explanation:
Many bacteria have evolved the ability to recognize and destroy invading DNA as a defense mechanism against viral infection. Bacteria use restriction endonucleases that can distinguish between their own DNA and foreign DNA, such as that from invading viruses, known as phages. These enzymes function by cleaving specific DNA sequences found in the phage, thus neutralizing the potential threat. Additionally, the CRISPR-Cas system is another adaptive immune mechanism that provides bacteria the capability to 'remember' past infections. Foreign DNA segments from viruses introduced into the bacterial genome during previous encounters serve as a genetic memory, guiding the cas proteins to target and cleave the viral DNA during subsequent infections.
Furthermore, the process of transformation facilitates horizontal gene transfer (HGT), where bacteria take up free DNA from the environment and potentially incorporate it into their own genome, granting them new characteristics such as antibiotic resistance or increased virulence. Competent bacteria convert the environmental DNA into a single-stranded form to escape degradation by nucleases and to facilitate recombination into their genome.