On what principle does DNA fingerprinting work?
On what principle does DNA fingerprinting work?
-
DNA fingerprinting is a method for comparing the DNA sequences of any two individuals.
-
99.9% of the base sequences in all human beings are identical. It is the remaining 0.1% that makes every individual unique.
-
It is a really difficult and time-consuming task to sequence and compare all 3 × 109 bases in two individuals. So, instead of considering the entire genome, certain specific regions called repetitive DNA sequences are used for comparative study.
Basis of DNA Fingerprinting
-
Repetitive DNA is separated from bulk genomic DNA since it appears as a distinct peak during density gradient centrifugation.
-
Major peak: Formed by bulk DNA
Smaller peak: Satellite DNA
-
Satellites are of two types—micro-satellites and mini satellites, depending upon the base composition, length of segment and the number of repetitive units.
-
Satellites do not code for proteins, but have a major role to play in DNA fingerprinting.
-
Polymorphism is actually a result of mutation. A germ cell mutation (which can pass on to the next generation through sexual reproduction) gives rise to polymorphism in populations.
-
In other words, an inheritable mutation if observed in higher frequencies in a population is known as polymorphism.
-
Polymorphisms arise normally in non-coding sequences because mutations in non-coding sequences do not affect an individual’s reproductive ability.
-
DNA fingerprinting is a method for comparing the DNA sequences of any two individuals.
-
99.9% of the base sequences in all human beings are identical. It is the remaining 0.1% that makes every individual unique.
-
It is a really difficult and time-consuming task to sequence and compare all 3 × 109 bases in two individuals. So, instead of considering the entire genome, certain specific regions called repetitive DNA sequences are used for comparative study.
Basis of DNA Fingerprinting
-
Repetitive DNA is separated from bulk genomic DNA since it appears as a distinct peak during density gradient centrifugation.
-
Major peak: Formed by bulk DNA
Smaller peak: Satellite DNA
-
Satellites are of two types—micro-satellites and mini satellites, depending upon the base composition, length of segment and the number of repetitive units.
-
Satellites do not code for proteins, but have a major role to play in DNA fingerprinting.
-
Polymorphism is actually a result of mutation. A germ cell mutation (which can pass on to the next generation through sexual reproduction) gives rise to polymorphism in populations.
-
In other words, an inheritable mutation if observed in higher frequencies in a population is known as polymorphism.
-
Polymorphisms arise normally in non-coding sequences because mutations in non-coding sequences do not affect an individual’s reproductive ability.
