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Restriction Fragment Length Polymorphisms
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What is the significance of the number and location of RFLPs a particular individual has in its genome? A polymorphism is a genetic characteristic that varies among individuals in a population. For some polymorphisms there are major consequences in having one genotype versus another. Many genetic diseases are the result of a polymorphism at a single locus. For example individuals that are homozygous for the sickle cell allele have a serious illness while individuals that are homozygous for the ‘normal’ allele or are heterozygous do not have the illness. Restriction sites are short sequences recognized by restriction enzymes. Because these sequences are fairly short they are likely to appear by chance at random locations in the genome due to mutation. Restriction mutations in protein coding regions may be removed by natural selection if they result in a less functional product. Otherwise the RFLP differences among individuals have no functional significance. They are useful in DNA fingerprinting but do not affect the organism.

View the animation below, then complete the quiz to test your knowledge of the concept.





1The population is said to be ________ for restriction enzyme fragment patterns.
A)polygenic
B)polymorphic
C)polyphyletic
D)pericentric
E)pleotropic


2RFLPs result because individuals in a population have
A)DNA sequence differences in the pattern of restriction sites.
B)DNA sequence differences that create different proteins.
C)DNA sequence differences that make DNA more susceptible to denaturation.
D)different mutations that alter the length of their mRNA.
E)different mutations that make their mRNA more susceptible to degradation.


3RFLPs are separated by
A)the polymerase chain reaction.
B)northern blotting.
C)gel electrophoresis.
D)western blotting.
E)dideoxynucleotide sequencing.


4RFLPs may arise through mutations.
A)True
B)False


5RFLPs may be used as markers to identify people at risk of certain genetic disorders.
A)True
B)False





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