Plasmid conformations on agarose gel: Arrange plasmid DNA forms in decreasing apparent molecular size (slowest to fastest migration) as typically observed after electrophoresis.

Introduction / Context:
A single plasmid sequence can appear as multiple bands on agarose gel because different topological forms migrate differently. Recognizing the order is crucial for interpreting cloning results and confirming plasmid integrity.

Given Data / Assumptions:

• Three common forms: open circular (nicked), linear (restriction cut), and supercoiled (covalently closed circular).
• Agarose concentration and voltage are in a typical analytical range.
• “Decreasing apparent molecular size” corresponds to migration from slowest (appears largest) to fastest (appears smallest).

Concept / Approach:
Although all forms have identical true molecular weight, conformation alters gel sieving. Open circular DNA is the least compact and migrates most slowly (appears largest). Linear DNA has intermediate mobility. Supercoiled DNA is most compact and migrates fastest (appears smallest).

Step-by-Step Solution:
Rank by compactness: open circular < linear < supercoiled.Map compactness to migration: less compact → slower; more compact → faster.Order in decreasing apparent size (slow to fast): open circular → linear → supercoiled.Select the option matching this sequence.

Verification / Alternative check:
Digest the sample with a single cutter to convert all to linear; the band shifts to the intermediate position, confirming band identities.

Why Other Options Are Wrong:

• Any sequence placing supercoiled before linear in apparent size is inconsistent with typical mobility.
• Repeated incorrect sequences ignore the compactness-mobility relationship.

Common Pitfalls:
Confusing “molecular weight” with “apparent size”; on gels, conformation dominates mobility for plasmids.

Final Answer:
Open circular, linear plasmid, super coiled plasmid