How do autosomal traits differ from sex-linked traits?
The autosomal chromosomes are the non sex chromosomes. The sex chromosomes determine the sex of an individual. In humans we have 23 pairs of chromosomes in total. This is made up of 22 pairs of autosomal chromosomes and one pair of sex chromosomes.
The autosomal pairs are all recognisable by specific shapes and are numbered 1-22. The pairs are identical in size, shape, the genes that they carry, but not always the same form of the gene
The sex chromosomes are so named because of their shape but unlike autosomal pairs they are not identical in shape. The X chromosome is shaped like a letter X. They are non identical in shape as the Y chromosome has part of the chromosome missing creating a Y shape, although they are named simply because Y is the next letter in the alphabet to X, rather than because of this shape.
I n females this pair of sex chromosomes are both of the X TYPE, denoting female as XX. Males have an X and a Y chromosome thus denoting males as XY.
Traits carried on chrosomes 1-22 are autosomal traits. Traits carried on the X and Y chromosomes are sex linked traits.
Not all traits on the X and Y chromosome are to do with sexual characteristics eg colour blindness is a trait found on the X chromosome. It is not on the Y chromosome as it is found on the part of the X chromosome that is missing in the Y chromosome.
The inheritance of colour blindness therefore is linked to the inheritance of the trait on an X chromosome. Colour blindness has nothing to do with sexual characteristics.
- Autosomal traits would show Mendelian inheritance pattern but sex-linked traits would show criss cross inheritance.
- Sex-linked trait is often controlled by gene present only on X chromosome, hence no corresponding allele is present on Y chromosome.
Male members of a population are affected in more number by sex-linked genetic diseases, which is not the case when the trait is autosomally linked.