Page 14 - Lesson Notes- Principle of inheritance & Variation

When sperm having Y chromosome the sex of baby is male and when sperm carrying

X chromosome fertilse the egg, the sex of baby is female.

Mutationis a phenomenon which results in alternation of DNA sequence and consequently

results in the change in the genotype and phenotype of an organism. The mutations that

arise due to due to change in single base pair of DNA are called point mutation e.g Sickle cell
anaemia.

Pedigree Analysis

The analysis of traits in several of generation of a family is called the pedigree analysis.

The inheritance of a particular trait is represented in family tree over several

generations. It is used to trace the inheritance of particular trait, abnormality and
disease.

Genetic Disorders

Broadly, genetic disorders may be grouped into two categories – Mendelian disorders and

Chromosomal disorders.

Mendelian Disorders Chromosomal disorders

These are caused due to absence or excess of one or
These are due to alteration in a
more chromosomes or abnormal arrangement of
single gene.
one/more chromosomes.

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