Number of chromsomes 25 Trisomy single trisomy chromsomes

Number of chromsomes = 25

Trisomy (single trisomy) = chromsomes 4

What is the number of gametes for this species?

Solution

Answer is one gamete with 12 chromosomes, and another gamete with 12+1 chromosomes.

Number of chromosomes is 25, and then this shows that this organism has got one extra chromosome due to trisomic condition at chromosome 4. If this person produces gametes, one gamete will have 12 chromosomes and another gamete will have 12+1 chromosomes.

In actual condition, the number of chromosomes will be 24, so it will produce gamete carrying 12 chromosomes, when egg and sperm carrying 12 chromosomes will fuse together, it will produce zygote or fertilized egg with altogether 24 chromosomes. In some condition, the gametes will try to carry extra chromosomes and they with 12+1 combines with another gamete with 12 chromosomes will result in 2n+1 condition (25 chromosomes).