Types+of+Chromosomes

__Summary__
A human on average has 23 pairs of chromosomes. Most students learn this fact in high school biology class, but what some people may not know is that there are actually two different types of chromosomes. These two different chromosomes are called autosomes and sex chromosomes. [|To learn more about autosomes, visit this link!] || The sex chromosomes are the 23rd and final chromosome pair that determines genetic sex. In females, the sex chromosomes are the same size and shape as each other and are called "XX". Males are different, with their chromosomes called "XY" and the sizes of the "X" and "Y" differing. The "X" in a male is the same size as the "X" in a female, with the "Y" being 1/5 the size of the "X". Children get //one// sex chromosome from each parent, an "X" from the mother and either an "X" //or// "Y" from the father, which is why a child's gender comes as a suprise when they are born. The "Y"-carrying sperm are smaller and faster than the "X"-carrying sperm, which is why the "Y"-carrying sperm generally reach the ovum before the "X"-carrying sperm. The "X"-carrying sperm have an advantage in the reproductive tract of a woman because they are more resistant to the acidity in the tract than the "Y"-carrying sperm; however, during ovulation the reproductive tract is less acidic which ultimately gives the advantage back to the "Y"-carrying sperm. This phenomenon explains why the sex ratio of males to females is for every 105 males there are 100 females born. The diet of the mother during time of conception is another factor that is related to the sex of the child. In a study with British women, the women that had the better nutrition had 56% male fetuses whereas women with the worst nutrition had 45% male fetuses. [|To learn more about sex chromosomes, visit this link!] ||
 * = **Autosomes** ||= **Sex Chromosomes** ||
 * The autosomes are the 1st through the 22nd chromosome pairs . Autosomes are usually the same size and shape as their partner chromosome.

__Genetic Disorders__
Genetic disorders can occur from both autosomes and sex chromosomes. Autosomal disorders can be cause by either autosomal recessive or autosomal dominate. Autosomal recessive disease is when a child recieves two recessive alleles that are abnormal. Autosomal dominate disease is caused by a child receiving at least one dominate allele that is abnormal.

Sex -linked disorders can be caused by a mutation on either the "X" or "Y" chromosomes. Typically males are more prone to developing X-link recessive disorders ibecause they have only one "X" chromosome. If the "X" chromosome has a recessive trait the male will develop the disorder.Females can recieve X-linked recessive only if they recieve two mutated genes, one from each parent. There are also X-linked dominant disorders as well. If the father is affected then only the daugher can recieve the mutated gene. In contrary, if the mother is affected then bother the son and daugher can recieve the mutated gene. Finally ther are Y-linked disorders. These disorders are passed down from father to son. The son must recieve a mutated "Y" chromosome inorder to inherit it.