How does gain or loss of chromosome(s) takes place in humans ? Describe one example each of chromosomal disorder along with the symptoms involving an autosome and a sex chromosome.

Explanation

Failure of segregation of chromatids during cell division cycle results in the gain or loss of a chromosome(s) (aneuploidy)
Autosomes :-
Down's syndrome : The cause is the presence of an additional copy of the chromosome number 21 (trisomy of 21).
The affected individual is
`**" "` short statured with small round head,
`**" "`furrowed tongue and partially open mouth
`**" "`Palm is broad with characteristic palm crease.
`**" "`Physical, psychomotor and mental dvelopment is retarded.
Sec chromosomes :-
Klinefelter's Syndrome : This is caused due to the presence of an additional copy of X- chromosome resulting into a karyotype of 47, XXY.
Such an individual has overall masculine development
`**" "`has overall masculine development
`**" "`feminine dvelopment is also expressed by the development of (breast/ gynaecomastia). such individuals are sterile.