Why do the fragments of DNA in gel electrophoresis move away from the negative cathode?

• A. DNA is negatively charged and attracted to the positive anode.
• B. DNA is positively charged and attracted to the positive anode.
• C. DNA is negatively charged and attracted to the positively charged agarose gel.
• D. DNA is positively charged and attracted to the negatively charged agarose gel.

Answer: (A)

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 and charge.
2. Recognize that DNA molecules are negatively charged due to their phosphate backbone. This is a key factor in their movement during electrophoresis.
3. Identify the setup of the gel electrophoresis apparatus: The gel is placed in a buffer solution, and electrodes are connected to create an electric field. The negative cathode is at one end, and the positive anode is at the other.
4. Explain the movement of DNA fragments: Since DNA is negatively charged, it is repelled by the negative cathode and attracted towards the positive anode.
5. Clarify the role of the agarose gel: The gel acts as a medium that allows the DNA fragments to move through it, separating them based on size as smaller fragments move faster than larger ones.