Multiple Choice
How does the data from X-ray diffraction support Watson and Crick's model of the DNA double helix?
34. Nucleic Acids
DNA Double Helix
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In an agarose gel electrophoresis experiment, what can a geneticist conclude about the bands of DNA closest to the wells?
A
They represent DNA fragments with the lowest charge.
B
They represent DNA fragments with the highest charge.
C
They represent the smallest DNA fragments.
D
They represent the largest DNA fragments.
Verified step by step guidance1
Understand the principle of agarose gel electrophoresis: DNA fragments are separated based on size, with smaller fragments moving faster and further through the gel matrix than larger ones.
Recognize that DNA is negatively charged due to its phosphate backbone, and when an electric field is applied, DNA fragments migrate towards the positive electrode.
Consider the position of the bands: DNA fragments that are closest to the wells have not traveled far, indicating they are larger in size.
Recall that larger DNA fragments experience more resistance moving through the gel matrix, thus they migrate slower and remain closer to the wells.
Conclude that the bands of DNA closest to the wells represent the largest DNA fragments, as they have moved the least distance through the gel.
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