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 hybridized with a probe for the gene pep during a Southern blot. Where in the gel is the pep gene located? 

Key Concepts

Restriction Enzymes

Restriction enzymes are proteins that cut DNA at specific sequences, creating fragments of varying lengths. These enzymes are crucial in molecular biology for cloning, DNA mapping, and analysis. The pattern of DNA fragments produced by these enzymes can be visualized using gel electrophoresis, allowing researchers to determine the presence and size of specific DNA sequences.

Gel Electrophoresis

Gel electrophoresis is a technique used to separate DNA fragments based on their size. When an electric current is applied, smaller fragments move faster through the gel matrix than larger ones, creating distinct bands. By comparing the banding pattern to known standards, researchers can infer the sizes of the fragments and identify specific DNA sequences, such as the location of a gene.

Southern Blotting

Southern blotting is a method used to detect specific DNA sequences within a complex mixture. After gel electrophoresis, DNA fragments are transferred to a membrane and hybridized with labeled probes that bind to complementary sequences. This technique allows for the identification of specific genes, such as the pep gene in this case, by visualizing the bands that correspond to the probe's binding.