Identical Twins
Identical Twins are a really cool thing to learn about. There are many different definitions of a "twin," but identical twins are truly unique. Identical twins form when one fertilized egg splits. They are so unique because even though they have the same genotypes for each of their traits, they are not exactly identical. Let's take the two couples on the right for example. The two women, Diane and Darlene Nettemeier, met the two identical twin brothers, Craig and Mark Sanders. Each woman was oddly attracted to the man who had opposite traits as her. The quiet woman attracted to the loud and boisterous man, and the loud woman was attracted to the quiet man. The two sisters first saw Mark standing across the room. Mark saw them and went upstairs to get his brother from their hotel room, telling him that he had saw two beautiful women standing in the lobby. The two brothers went back downstairs and each started to fall in love with the other twins. Once the convention ended, the two men flew back to the girls' hometown, St. Louis, Missouri and the two couples went on a double date to a baseball game. After dating for a while, both couples went to Las Vegas and won thousands of dollars! They thought it was their lucky day, but it was just getting started. After winning, each man knelt down on one knee and proposed! The women celebrated their marriages with a joint wedding and they each wore matching gowns.
Fun Fact: Diane and Craig actually have identical twin sons of their own! This miraculous event let them beat the 1 in 1,000,000 odds!
Fun Fact: Diane and Craig actually have identical twin sons of their own! This miraculous event let them beat the 1 in 1,000,000 odds!
The Overview
The chances of having a serious birth defect is about 2-3% in North America. It is now possible to connect some some of the inherited genetic defects to specific chromosome irregularities. This can be examined by getting small tissue samples from adults, kids and unborn babies. Irregular numbers of chromosomes and missing or deformed can be easily observed. To find out if a mother will give birth to a child with serious birth defects you can sample the embryonic or the fetal cells within the uterus. Using this method there are now more than 80 common types of chromosomal abnormalities. The child’s gender can be determined by noting whether its karyotype includes X and Y sex chromosomes or only X’s. Males express x-linked traits in phenotypes.Chromosomal defects are surprisingly frequent. About 20% of all human conceptions have then. As many as 1 in 118 newborn infants in the United States inherit such an abnormality. Most of this is a result of a failure of meiosis in the production of sperm and ova. It's estimated that ⅕ sperm cells produced by a healthy man's sperm is grossly defective. There are two major categories of chromosomal abnormalities:
1. Irregular number of chromosomes.
2. Structural modification in a chromosome. The normal amount of chromosomes is 46. You get 23 from your mom and 23 from your dad. There can be complete multiples of sets like 23+23+23 and its known as polyploidy. Also there can be an addition or loss of chromosomes within a set like 23+22+23+24 which is known as monosomy. If there are too few chromosomes it is referred to as monosomy. If there are one to many, then it is known as trisomy.
1. Irregular number of chromosomes.
2. Structural modification in a chromosome. The normal amount of chromosomes is 46. You get 23 from your mom and 23 from your dad. There can be complete multiples of sets like 23+23+23 and its known as polyploidy. Also there can be an addition or loss of chromosomes within a set like 23+22+23+24 which is known as monosomy. If there are too few chromosomes it is referred to as monosomy. If there are one to many, then it is known as trisomy.