PSYC 2076 Lecture Notes - Lecture 3: Preterm Birth, Umbilical Cord, Heredity
Document Summary
3 the start of life: genetics and prenatal development 2/3/2015 7:58:00. It starts with the gametes sex cells that form a new cell at conception. Chromosomes determine everything from hair color and eye color to sex. Whether you are a male or female depends on the presence or absence of certain chromosomes: sex chromosomes x-y. The male gametes or sperm cells in humans and other mammals are heterogametic - contain one of two types of sex chromosomes. The female gametes or eggs however, contain only the x sex chromosome and are homogamatic. The sperm cell determines the sex of an individual in this case. If a sperm cell containing an x chromosome fertilizes an egg, the resulting zygote will be xx or female. If the sperm cell contains a y chromosome, then the resulting zygote will be xy or male: multiple births. This is much more common in animals than in people.
