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Principles of Inheritance and Variation — BIOLOGY STD 12 Science — Question

Rajasthan BoardEnglish MediumSTD 12 ScienceBIOLOGYPrinciples of Inheritance and Variation2 Marks
Question
What is pedigree analysis? Suggest how much an analysis can be useful.
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Answer

→ The idea that disorders are inherited has been prevailing in the human society since long. This was based on the heritability of certain characteristic features in families.
→ After the rediscovery of Mendel's work the practice of analysing inheritance pattern of traits in human beings began.
→ Since it is evident that control crosses that can be performed in pea plant or some other organisms, are not possible in case of human beings, study of the family history about inheritance of a particular trait provides an alternative.
→ Such an analysis of traits in several generations of a family is called the pedigree analysis.
→ In the pedigree analysis, the inheritance of a particular trait is represented in the family tree over generations.
→ In human genetics, pedigree study provides a strong tool, which is utilised to trace the inheritance of a specific trait, abnormality or disease.
→ Each and every feature in any organism is controlled by one or the other gene located on the DNA present in the chromosomes.
→ DNA is the carrier of genetic information. It is hence transmitted from one generation to the other without any change or alternation. However, changes or alteration do take place occasionally.
→ Such an alteration or change in the genetic material is referred to as mutation.
→ A number of disorders in human beings have been found to be associated with the inheritance of changed or altered genes or chromosomes.
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(b) Representative pedigree analysis of (a) Autosomal dominant trait (for example: Myotonic dystrophy)
(b) Autosomal recessive trait (for example: Sickle-cell anaemia)

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