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Question 1:

What is the purpose of agarose gel electrophoresis?

A) Separating proteins based on size
B) Analyzing DNA or RNA fragments based on size
C) Determining protein concentration
D) Visualizing protein-protein interactions

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Explanation: The correct answer is B) Analyzing DNA or RNA fragments based on size. Agarose gel electrophoresis is commonly used to separate DNA or RNA fragments based on their size. It allows for the visualization and analysis of nucleic acids, such as DNA fragments obtained from PCR amplification or restriction digests, by their migration through the gel in response to an electric field.

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Question 2:

What is the purpose of adding ethidium bromide to the agarose gel during electrophoresis?

A) Stabilizing the gel matrix
B) Enhancing DNA or RNA detection
C) Breaking hydrogen bonds
D) Denaturing the DNA or RNA

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Explanation: The correct answer is B) Enhancing DNA or RNA detection. Ethidium bromide is commonly added to the agarose gel or the running buffer during electrophoresis to enhance the detection of DNA or RNA. Ethidium bromide intercalates between the DNA or RNA base pairs and becomes fluorescent when exposed to ultraviolet (UV) light, allowing for the visualization of DNA or RNA bands in the gel.

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Question 3:

Which type of charge does DNA or RNA carry in agarose gel electrophoresis?

A) Positive
B) Negative
C) Neutral
D) Variable

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Explanation: The correct answer is B) Negative. DNA or RNA molecules carry a negative charge in agarose gel electrophoresis. This is due to the negatively charged phosphate groups in the DNA or RNA backbone. When an electric field is applied, the negatively charged DNA or RNA fragments migrate towards the positive electrode.

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Question 4:

Which buffer is commonly used for agarose gel electrophoresis of nucleic acids?

A) TAE buffer
B) SDS-PAGE buffer
C) Proteinase K buffer
D) Running buffer

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Explanation: The correct answer is A) TAE buffer. TAE (Tris-Acetate-EDTA) buffer is commonly used for agarose gel electrophoresis of nucleic acids. It provides the necessary ionic strength and pH for the electrophoretic separation of DNA or RNA fragments. The EDTA in TAE buffer helps prevent DNA degradation by chelating divalent cations that can act as nucleases.

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Question 5:

Which agarose gel concentration is generally used for resolving larger DNA fragments?

A) 0.5%
B) 1%
C) 2%
D) 5%

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Explanation: The correct answer is C) 2%. A 2% agarose gel concentration is commonly used for resolving larger DNA fragments in agarose gel electrophoresis. Higher agarose concentrations provide a denser gel matrix, allowing for better resolution of larger DNA fragments, while lower concentrations are suitable for resolving smaller fragments.