BIOLOGY
STRUCTURE OF NUCLEIC ACIDS
|
Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
|
|
|
the smaller fragments travel faster and thus are closer to the negative end of the gel
|
|
|
the smaller fragments travel faster and thus are closer to the positive end of the gel
|
|
|
the larger fragments travel faster and thus are closer to the negative end of the gel
|
|
|
the larger fragments travel faster and thus are closer to the positive end of the gel
|
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: -Why do the fragments of DNA in gel electrophoresis move away from the negative cathode? DNA is negatively charged and attracted to the positive anode. DNA is positively charged and attracted to the positive anode.
Detailed explanation-5: -It is important to note that different forms of DNA move through the gel at different rates. 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.