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.
Picture 1: Genes, chromosomes and DNA. The chromosomes (see Picture 2) numbered 1 to 22 look the same in males and females. These are called the autosomes. Pair number 23 is different in males and females and they are called the sex chromosomes. There are two kinds of sex chromosome, one called the X chromosome and one called the Y chromosome.