Q14 of 40 Page 1

‘‘A very small sample of tissue or even a drop of blood can help determine paternity’’. Provide a scientific explanation to substantiate the statement.

The above statement can be substantiated through “DNA fingerprinting” by Southern blot method and by PCR (polymerase chain reaction).

DNA fingerprinting involves determining nucleotide sequences of certain areas of DNA which are unique to each individual.


The DNA sample can be obtained from a very small tissue or even a drop of blood can be used. The basis of DNA fingerprinting id DNA polymorphism. An individual inherits 50% of the chromosomes from maternal and 50% from the paternal parent. Small amount of blood or tissue is taken and amplified by PCR, which can be used in DNA fingerprinting, so as to identify the paternity.


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(a) How are Mendelian inheritance, polygenic inheritance and pleiotropy different from each other ?

(b) Explain polygenic inheritance pattern with the help of a suitable example.


OR


(a) Draw a labelled diagram of a ‘‘replicating fork’’ showing the polarity. Why does DNA replication occur within such ‘forks’ ?


(b) Name two enzymes involved in the process of DNA replication, along with their properties.