What process is shown most directly in the diagram below? A. Gel electrophoresis B. Polymerase chain reaction (PCR) C. Karyotyping D. Use of restriction enzymes 1.4.2 Quiz: DNA Fingerprinting Question 10 of 10 What process is shown most directly in the diagram below? Electrodes 40 25 M05 Lane (D) of Known fragment sizes. Kilobase pairs Chamber filled with Unknown DNA size samples buffer solution Well: Agarose Ge
The Correct Answer and Explanation is:
The correct answer is:
A. Gel electrophoresis
Explanation
The process shown most directly in the diagram is gel electrophoresis, a common laboratory technique used to separate DNA fragments based on their size. In this setup, DNA samples are loaded into wells at one end of an agarose gel, which is placed in a chamber filled with a buffer solution. Electrodes are connected at both ends—negative (-) at the top near the wells and positive (+) at the bottom—creating an electric field across the gel when powered.
Because DNA molecules carry a negative charge due to their phosphate backbone, they are pulled toward the positive electrode when an electric current is applied. As the DNA migrates through the porous gel matrix, smaller fragments move faster and farther than larger ones, effectively sorting them by size.
In the diagram, Lane D represents a DNA ladder or marker, which contains fragments of known sizes (in kilobase pairs). This lane serves as a reference to estimate the sizes of unknown DNA samples in other lanes (A, B, and C).
This technique is critical in DNA fingerprinting, forensic analysis, genetic testing, and molecular biology research, allowing scientists to compare DNA profiles, identify genetic relationships, or verify the success of techniques like PCR (Polymerase Chain Reaction).
The other answer choices are incorrect for the following reasons:
- B. Polymerase chain reaction (PCR) refers to amplifying DNA, not separating it.
- C. Karyotyping involves viewing whole chromosomes under a microscope, not fragment separation.
- D. Use of restriction enzymes refers to cutting DNA at specific sequences, which usually occurs before gel electrophoresis but is not shown directly in the diagram.
Thus, the process depicted in the diagram is most directly gel electrophoresis.
