The gel presented here shows the pattern of bands of fragments produced with several restriction enzymes. The enzymes used are identified above the lanes of the gel, and six possible restriction maps are shown in the column to the right.
One of the six restriction maps shown is consistent with the pattern of bands shown in the gel.
The highlighted bands (magenta) in the gel were hybridized with a probe for the gene pep during a Southern blot. Where in the gel is the pep gene located? 

Verified step by step guidance

1. Step 1: Understand the experimental setup by reviewing how restriction enzymes cut DNA at specific sequences, producing fragments of varying lengths that appear as bands on a gel after electrophoresis.
2. Step 2: Examine the gel lanes corresponding to each restriction enzyme and note the sizes and number of bands produced, paying special attention to the magenta-highlighted bands that hybridized with the pep gene probe during the Southern blot.
3. Step 3: Compare the observed band patterns for each enzyme with the six possible restriction maps provided, focusing on which map's predicted fragment sizes and arrangement match the gel's band pattern, especially the bands that hybridize with the pep probe.
4. Step 4: Identify the fragment(s) in the gel where the pep gene is located by matching the hybridized bands to the corresponding fragment(s) in the restriction map that contains the pep gene sequence.
5. Step 5: Conclude the location of the pep gene on the restriction map by correlating the hybridized band sizes with the fragment sizes in the map, confirming which restriction map is consistent with the gel pattern and the Southern blot results.

Key Concepts

Restriction Enzymes and DNA Fragmentation

Restriction enzymes cut DNA at specific sequences, producing fragments of varying lengths. When DNA is digested with different enzymes, the pattern of fragments reflects the locations of their recognition sites. Understanding how these enzymes work is essential to interpret gel band patterns and map DNA.

Gel Electrophoresis and Band Patterns

Gel electrophoresis separates DNA fragments by size, with smaller fragments migrating farther through the gel. The resulting band pattern represents the sizes of DNA pieces after enzyme digestion. Comparing band patterns across lanes helps identify which restriction map matches the observed data.

Southern Blotting and DNA Probes

Southern blotting transfers DNA fragments from a gel to a membrane, where a labeled probe hybridizes to a specific gene sequence. The location of the probe signal on the gel indicates which fragment contains the gene of interest, allowing identification of the gene's position within the restriction map.