Question

Study the two different crosses given below:

Identify the abnormalities 1 and 2 in the offsprings of given crosses and distinguish between them.

Answer 1

Cross I Analysis:

1. Gametes involved: 
   • Mother (44 + XX) produces abnormal (23 + X) and (21 + X) gametes.
   • Father (44 + XY) produces normal (22 + X) and (22 + Y) gametes.
2. Resulting Offspring: (23 + X) + (22 + X) = (45 + XX) → Autosomal trisomy (such as Down Syndrome)
3. Abnormality 1: Autosomal trisomy such as Down Syndrome (45 + XX)

Cross II Analysis:

1. Gametes involved: 
   • Mother (44 + XX) produces (22 + XX) and (22 + O). O means no sex chromosome.
   • Father (44 + XY) produces normal (22 + X) and (22 + Y) gametes.
2. Resulting Offspring: (22 + XX) + (22 + Y) = (44 + XXY) → Klinefelter syndrome
3. Abnormality 1: Klinefelter syndrome

	Down Syndrome	Klinefelter syndrome
Karyotype:	45, XX	47, XXY
Cause:	Trisomy of 21 chromosomes	Short stature, furrowed tongue, broad palm, mentally retarded.
Features:	Trisomy X (sex chromosome)	Taller height, learning difficulties, and underdeveloped genitalia