Question

BamHI is a restriction enzyme derived from Bacillus amyloliquefaciens that recognizes short palindromic sequences in DNA. When the enzyme recognizes these sequences, it cleaves the DNA. What purpose would restriction enzymes have in a bacterium like Bacillus? (A) They are enzymes that no longer have a purpose because evolution has produced better enzymes. (B) They destroy extra DNA that results from errors in binary fission. (C) They protect Bacillus from invading DNA due to viruses. (D) They prevent, or restrict, DNA replication when the cell isn't ready to copy its DNA.

Short answer

(C) They protect Bacillus from invading DNA due to viruses.

Step-by-step solution

Understand the role of restriction enzymes

Restriction enzymes are proteins that can recognize and cleave specific DNA sequences. BamHI is a restriction enzyme that recognizes short palindromic sequences in DNA. It is important to understand that restriction enzymes protect bacteria against invading foreign DNA, such as DNA from viruses.

Evaluate each answer option

Now, let's evaluate each answer option. (A) They are enzymes that no longer have a purpose because evolution has produced better enzymes. - This option is incorrect because restriction enzymes still serve an important role in the defense mechanism of bacteria. (B) They destroy extra DNA that results from errors in binary fission. - This option is incorrect because restriction enzymes do not specifically target extra DNA that results from errors in binary fission. Their main purpose is to protect the bacterium against foreign DNA. (C) They protect Bacillus from invading DNA due to viruses. - This option is correct because restriction enzymes, like BamHI, recognize foreign DNA (such as viral DNA) and cleave it to protect the bacterium. (D) They prevent, or restrict, DNA replication when the cell isn't ready to copy its DNA. - This option is incorrect because restriction enzymes do not control or regulate the replication process in bacterial cells. Their main purpose is protecting the bacterium against foreign DNA.

Select the correct answer

Based on the analysis of each option, the correct answer is: (C) They protect Bacillus from invading DNA due to viruses.