1 Colored Egg Layer Chickens. The Araucana is a pure breed of chicken originating in Chile. 2  Ameraucana chickens were developed in the 1970âs in the United States from Araucanas. They were developed as a practical barnyard fowl that laid pastel shelled eggs, but without some of the limiting genetic factors related to rumplessness and tufts.
sex chromosome. a chromosome, differing in shape or function from other chromosomes, that determines the sex of an individual.
The sex chromosomes determine whether you are a boy (XY) or a girl (XX). The other chromosomes are called autosomes. The karyotype of a male human being. The largest chromosome, chromosome 1, contains about 8000 genes. The smallest chromosome, chromosome 21, contains about 300 genes.