Genetic Disorder | Class 11 Biotechnology

 Haploid cells have only one copy of the chromosome while diploid cells have two copies of the same chromosome. 

• Any deviation where one or few chromosomes are either absent or present in multiple copies is called aneuploidy. 

• In polyploidy condition, the entire set of chromosome is multiplied. 

• A syndrome is a specific collection of signs or symptoms suggesting a particular disease, while a disease is a broader term that refers to abnormal physiological response to internal or external factors.

 • Symptoms are subjective and signs are objective. 

• Structural chromosomal abnormalities can be caused by deletion, duplication, inversion and translocation. 

• Individuals with Down syndrome has an extra chromosome 21, i.e., there are three copies of chromosome 21 (trisomy 21). 

• Individuals with Klinefelter syndrome has an extra X chromosome (XXY) and is observed only in males.

• Turner syndrome arises due to missing one X chromosome in affected females. 

• Monogenic disease is caused by modifications in a single gene. They can be classified into the following: autosomal recessive, autosomal dominant, X-linked recessive and X-linked dominant. 

Polygenic disorder is caused by the defect or combined action of more than one gene. 

Mitochondrial inheritance and diseases are caused due to defect or mutation in the genes coding for critical enzymes present in the mitochondria. 

• Four types of structural chromosomal abnormalities exist: deletion, duplication, inversion and translocation.

 • Down syndrome occurs due to trisomy 21 and are characterised by features like moon like face, protruding tongue, muscular hypotonia, palmar crease and so on. 

Klinefelter syndrome occurs due to presence of an extra X chromosome in males and is characterised by tall height, enlarged breasts, coarse voice, hypogonadism and so on.

 • Turner syndrome occurs due to absence of one X chromosome in females and is characterised by short stature, webbed neck, small breasts, no menstruation and so on.  

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