THE MOLECULAR BASIS OF INHERITANCE
STRUCTURE OF NUCLEIC ACIDS
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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the smaller fragments travel faster and thus are closer to the negative end of the gel
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the smaller fragments travel faster and thus are closer to the positive end of the gel
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the larger fragments travel faster and thus are closer to the negative end of the gel
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the larger fragments travel faster and thus are closer to the positive end of the gel
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Detailed explanation-1: -DNA fragments are negatively charged, so they move towards the positive electrode. Because all DNA fragments have the same amount of charge per mass, small fragments move through the gel faster than large ones.
Detailed explanation-2: -Shorter DNA segments find more pores that they can wiggle through, longer DNA segments need to do more squeezing and up or down moving. For this reason, shorter DNA segments move through their lane at a faster rate than longer DNA segments.
Detailed explanation-3: -To separate DNA using agarose gel electrophoresis, the DNA is loaded into pre-cast wells in the gel and a current applied. The phosphate backbone of the DNA (and RNA) molecule is negatively charged, therefore when placed in an electric field, DNA fragments will migrate to the positively charged anode.
Detailed explanation-4: -Due to the molecular sieving action of the gel matrix, smaller sized DNA fragments are able to migrate further toward the positive electrode during a given time. Larger DNA fragments cannot move through the mesh easily and therefore migrate slower during a given amount of time.
Detailed explanation-5: -Supercoiled plasmid DNA, because of its compact conformation, moves through the gel fastest, followed by a linear DNA fragment of the same size, with the open circular form traveling the slowest.