Restriction enzymes — What do isoschizomers recognize when comparing different restriction endonucleases?

Introduction:
Restriction endonucleases are categorized by the sequences they recognize and how they cleave DNA. Isoschizomers are pairs (or sets) of enzymes from different organisms that recognize exactly the same DNA sequence. This question clarifies what “same” means in this context.

Given Data / Assumptions:

• Recognition sequence specifies the short DNA motif bound by the enzyme.
• Cleavage pattern (cut position) determines the ends generated (blunt vs sticky).
• Isoschizomers share both recognition and cleavage positions; neoschizomers recognize the same sequence but cut differently.

Concept / Approach:
Distinguish isoschizomers (same sequence, same cut) from neoschizomers (same sequence, different cut). Select the option that states both recognition and site are the same, which is the definition of isoschizomers.

Step-by-Step Solution:

Verification / Alternative check:
Enzyme catalogs list isoschizomer pairs (e.g., SphI and BbuI) that generate identical overhangs from the same motif; neoschizomers are listed separately.

Why Other Options Are Wrong:

Common Pitfalls:
Confusing isoschizomers with neoschizomers; overlooking methylation’s separate role in blocking cleavage without changing sequence identity.

Final Answer:
They recognize and cut the same sequence in the same way.