Which chromosomes do females have

There are genes on chromosomes other than the X or Y that also contribute to sex development. Gender identity is about who you know yourself to be, not about how your sex chromosomes look on a microscope slide. Posted in: Social Implications Comments are closed. Enter your email address to subscribe to this blog and receive notifications of new posts by email. This XY sex-determination system is found in most mammals as well as some reptiles and plants.

Whether a person has XX or XY chromosomes is determined when a sperm fertilizes an egg. Unlike the body's other cells, the cells in the egg and sperm — called gametes or sex cells — possess only one chromosome.

Gametes are produced by meiosis cell division, which results in the divided cells having half the number of chromosomes as the parent, or progenitor, cells.

In the case of humans, this means that parent cells have two chromosomes and gametes have one. All of the gametes in the mother's eggs possess X chromosomes. The father's sperm contains about half X and half Y chromosomes. The sperm are the variable factor in determining the sex of the baby. If the sperm carries an X chromosome, it will combine with the egg's X chromosome to form a female zygote.

If the sperm carries a Y chromosome , it will result in a male. During fertilization, gametes from the sperm combine with gametes from the egg to form a zygote. The zygote contains two sets of 23 chromosomes, for the required There are some variations, though. For example, trisomy X syndrome is caused by the presence of three X chromosomes instead of two. Turner syndrome occurs when women inherit only one copy of the X chromosome. Some women have a rare super color vision trait called tetrachromacy , which is linked to the X chromosome.

These women can see up to million shades of color because they have four types of cone cells in their eye instead of the usual three. Contrary to popular belief, calico is not a breed of cats, but rather a distinctive coat color pattern linked to the X chromosome. The patches of fur on a calico cat are orange and black, and the color depends on which X chromosome is inactivated within each patch of color. For example, the ZZ-ZW sex determination system used in birds, snakes, and some insects relies upon females to carry the mismatched chromosome pair ZW and males to carry the identical pair ZZ Figure 6.

If the three systems discussed above are compared in side-by-side Punnett squares Figure 7 , it is easy to see that sex determination is simply a matter of gamete assortment. Determinations of male and female character arise from a variety of different gamete combination patterns, all of which are the result of gender coding in sexually reproducing organisms. This page appears in the following eBook. Aa Aa Aa.

In humans and many other animal species, sex is determined by specific chromosomes. How did researchers discover these so-called sex chromosomes? The path from the initial discovery of sex chromosomes in to an understanding of their true function was paved by the diligent efforts of multiple scientists over the course of many years.

As often happens during a lengthy course of discovery, scientists observed and described sex chromosomes long before they knew their function. An idea inspired by the "X element". Before Her Time. The Life of Nettie Stevens. Figure 2: The darkling beetle, Tenebrio molitor.

The variety of sex determination systems. Figure 3: Example set of male human chromosomes. In the image, the X and Y chromosomes are indicated by arrows. Figure 4: Sex determination in humans. On the upper left, the female parent genotype is XX. The first X is labeled to the left of the top quadrant, while the second X is labeled outside the left quadrant. On the upper right, the male parent genotype is XY. The X is labeled to the right of the top quadrant, while the Y is labeled outside the right quadrant.

In this case, two of the four quadrants contain the genotype XX, resulting in female offspring; the remaining two quadrants contain the genotype XY, resulting in male offspring.