Which option gives the correct pair for bacterial DNA protection?

Correct answer: Methylase and methylation

The direct answer is A: methylase and methylation protect bacterial DNA. Bacteria may produce restriction enzymes to cut foreign DNA, such as invading phage DNA. To avoid cutting their own genome, a methylase adds methyl groups to particular bases in the bacterium’s DNA. This methylation marks self DNA and prevents the matching restriction enzyme from recognizing or cutting it, or otherwise protects the site. Option A is correct because it names both the enzyme and the protective modification. Option B is wrong: amylase digests starch and is not the usual protection system for restriction sites. Option C is wrong: lipase breaks down fats and has no role in marking bacterial DNA. Option D is wrong: chlorophyll and sunlight are associated with photosynthesis, not restriction-modification protection. The system works as a pair: restriction enzyme cuts unprotected foreign DNA, while methyltransferase or methylase modifies self DNA. Memory cue: methylation marks “self”; restriction cuts “foreign.”