Multiple Choice
In a standard DNA extraction protocol, what is the primary function of the lysis solution?
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18. Molecular Genetic Tools
Methods for Analyzing DNA
Multiple Choice
In agarose gel electrophoresis, how does DNA move through the gel when an electric field is applied?
A
DNA migrates toward the negative electrode (cathode) because its nitrogenous bases are positively charged.
B
DNA migrates toward the positive electrode (anode) because its phosphate backbone is negatively charged.
C
DNA migrates randomly through the gel due to Brownian motion rather than the electric field.
D
DNA remains stationary because the gel neutralizes DNA’s charge.
Verified step by step guidance1
Understand the structure of DNA, focusing on the phosphate backbone, which carries a negative charge due to the phosphate groups.
Recall that in agarose gel electrophoresis, an electric field is applied across the gel with a positive electrode (anode) and a negative electrode (cathode).
Recognize that because DNA is negatively charged, it will be attracted to the positive electrode (anode) when the electric field is applied.
Consider how the gel matrix acts as a molecular sieve, allowing smaller DNA fragments to move faster through the pores than larger fragments, but the direction of movement is determined by the charge and electric field.
Conclude that DNA migrates toward the positive electrode (anode) due to its negatively charged phosphate backbone, and not toward the negative electrode or randomly.
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