In the R+ lane, where is the 807 bp rfp fragment relative to ladder marks?

In the R+ lane, where is the 807 bp rfp fragment relative to ladder marks?

• A. Between 1,000 bp and 500 bp
• B. Between 4,000 bp and 5,000 bp
• C. At the top of the ladder
• D. At the bottom of the ladder

Answer: (A)

In gel electrophoresis, DNA fragments separate by size: smaller fragments migrate farther toward the bottom, and a ladder provides reference bands at known base-pair lengths. An 807 bp fragment is smaller than 1,000 bp but larger than 500 bp, so its band will appear between the 1,000 bp and 500 bp marks on the ladder. It wouldn’t sit at the top (largest) or bottom (smallest) of the ladder. Therefore, the 807 bp fragment is found between 1,000 bp and 500 bp.

In gel electrophoresis, DNA fragments separate by size: smaller fragments migrate farther toward the bottom, and a ladder provides reference bands at known base-pair lengths. An 807 bp fragment is smaller than 1,000 bp but larger than 500 bp, so its band will appear between the 1,000 bp and 500 bp marks on the ladder. It wouldn’t sit at the top (largest) or bottom (smallest) of the ladder. Therefore, the 807 bp fragment is found between 1,000 bp and 500 bp.