Question

describe the crosses you must preform and the phenotype patterns you observe to identify autosomal recessive and autosomal dominant traits, x-linked recessive, and linked traits.

Answer 1

To determine whether a trait is dominant or recessive : Observe the F1 and F1 reciprocal cross phenotypes.

The parental phenotype that appears in a heterozygous organism is dominant. When we test cross this genotype we will get 1:1 ratio of dominant : recessive.

The parental phenotype that reappears in the F2 generation is recessive. The only individual that must always be heterozygous when we're unaware that whether a gene is autosomal or sex linked is the F1 female. The phenotype of the F1 female is dominant.

To determine whether a trait is autosomal/sex-linked : Observe the males from the F1 and F1 reciprocal crosses. If a trait is sex-linked and present on X chromosome, the males from the F1 crosses will exhibit the phenotype inherited from their homozygous mothers. The results of reciprocal crosses would be different.

If the males from F1 reciprocal crosses resemble their sisters, then the trait is autosomal.

TRAIT	CHARACTERISTIC FEATURE
Autosomal dominant	The F1 progenies are all phenotypically mutant. The F1 and F1 reciprocal crosses give the same results.
Autosomal recessive	The F1 progenies are all phenotypically wild type (normal) The F1 and F1 reciprocal crosses give the same results.
X - linked dominant	The F1 males have the phenotype of their mothers. The F1 females are phenotypically mutant. The results of the reciprocal crosses are different.
X-linked recessive	The F1 males resemble their mothers. The F1 females are phenotypically wild type. The results of the reciprocal crosses are different.