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QuestionBiology

Does DNA move toward red or black? Why is this? A. DNA moves toward red because red is positively charged. B. DNA moves toward black because black is negatively charged. C. DNA moves toward the positive electrode (red) due to its negative charge.
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Step 1:
I'll solve this problem step by step, focusing on the electrophoresis principles of DNA movement.

Step 2:
: Understand DNA's Molecular Charge

- Each phosphate group ($$PO_{4}^{3-}$$) contributes multiple negative charges to the DNA molecule
- DNA molecules have a consistent negative charge due to their phosphate backbone

Step 3:
: Recall Electrophoresis Principles

- In gel electrophoresis, charged molecules move in an electric field - Negatively charged molecules are attracted to the positive electrode (anode) - The positive electrode is typically colored red in standard electrophoresis setups

Step 4:
: Analyze Charge Movement

- Since DNA is negatively charged, it will migrate toward the positive (red) electrode - This movement occurs because opposite charges attract in an electric field

Step 5:
: Eliminate Incorrect Options

- Option A is incorrect: Red is not positively charged - Option B is incorrect: Black is not negatively charged - Option C correctly describes the scientific principle

Final Answer

DNA moves toward the positive electrode (red) due to its negative charge. The key concept is that the negatively charged DNA molecules are attracted to the positively charged (red) electrode during electrophoresis.