How does DNA migrate from one end of the gel to the other during gel electrophoresis?

• A. DNA remains stationary because it is neutral and unaffected by the electric field.
• B. DNA migrates randomly in the gel without any directional preference.
• C. DNA migrates towards the negative electrode due to its positive charge.
• D. DNA migrates towards the positive electrode due to its negative charge.

Answer: (D)

Verified step by step guidance

1. Understand the basic principle of gel electrophoresis: It is a technique used to separate DNA fragments based on their size by applying an electric field to a gel matrix.
2. Recognize the charge properties of DNA: DNA molecules are negatively charged due to their phosphate backbone, which is important for their movement in an electric field.
3. Identify the direction of DNA migration: In gel electrophoresis, DNA migrates towards the positive electrode (anode) because opposite charges attract, and DNA is negatively charged.
4. Consider the role of the gel matrix: The gel acts as a sieve, allowing smaller DNA fragments to move faster and further than larger ones, which helps in separating them based on size.
5. Visualize the setup: The gel is placed in a buffer solution, and electrodes are connected to create an electric field. DNA samples are loaded into wells at one end of the gel, and as the electric field is applied, DNA migrates through the gel towards the positive electrode.