question_answer

DNA fingerprinting can help in solving a case of paternity dispute over the custody of a child by two different families. Do you agree? If yes, explain why?

Or

What conclusions were drawn by Darwin after his journey through a ship around the world?

Answer:

Yes, DNA fingerprinting is the technique used to solve the paternity dispute for a child. DNA fingerprinting is a technique of determining nucleotide sequences of certain areas of DNA which are unique to each individual.

The basis of DNA fingerprinting is DNA polymorphism. Although the DNA from different individuals is more alike than different, there are many regions of the human chromosomes that exhibit a great diversity. Such variable sequences are termed as ?polymorphic? (meaning many forms).

A special type of polymorphism, called VNTR (Variable Number of Tandem Repeats), is composed of repeated copies of a DNA sequence that lie adjacent to one another on the chromosome.

Procedure of DNA fingerprinting It is as follows

· Isolation of DNA from child, followed by its amplification using PCR.

· Digestion of DNA by restriction endonuclease.

· Separation of fragments by gel-electrophoresis.

· Southern blotting for transferring separated fragments to synthetic membranes.

· After hybridisation with the radiolabelled VNTR probe and autoradiography, bands of various sizes are formed, which varies from person to person.

· The patterns developed by sample A and B, can confirm that whether they belong to one person or two different persons.

Or

Following are the Darwin?s conclusions after his journey through a ship around the world.

· Over production Living beings have an innate ability of producing own kind of individuals for the continuity of race. It has been observed that more individuals of each kind are produced than that could possibly survive.

· Struggle for existence Individuals multiply in geometric ratio, whereas space and food remain almost limited.

· Variations Members of a population vary in size, form and other characteristics even though they look superficially similar, no two individuals are alike. These variations are gradual and those with adaptive value are passed on to the next generation. Survival of the fittest and natural selection During struggle for existence only those individuals could survive who exhibit beneficial variations and adapt better to changing environment. This is known as natural selection.

· Origin of species Natural selection results in modification of traits within a lineage, which over a period of long time can bring about evolution of original species into new one.