Autosomal Chromosomal Abnormalities

Where does DNA come from? What is DNA? What is a Trisomy? DNA comes from our parents, we get half from mom and the other half from dad. DNA is two strands of nucleotide bases coiled into a double helix. The four nucleotide bases are Adenine, Thymine, Cytosine, and Guanine. Adenine pairs with Thymine and Guanine pairs with Cytosine. Each set has 23 single chromosomes- 22 Autosomes and one X or Y sex chromosome. (Massimini, 2000). “Your mother can give you only an X chromosome, but your father can pass on an X or a Y chromosome. If you receive an X chromosome from your father, the XX pair makes you genetically a female. If you receive a Y chromosome from your father, then your XY pair you're genetically a male (mayoclinic). Trisomies occur when there is an extra chromosome. An example of this would be, we have a total of 46 chromosomes (23 from each parent). When one extra is added this is a trisomy because now there’s 47 chromosomes. “There are two different forms of trisomy they are as follows: Partial Trisomy- part of a chromosome attaches itself to another chromosome, and Mosaic Trisomy- every cell contains extra” (Massimini, 2000, p.48).

DNA replication is when cells make copies before they divide. DNA is held together by Hydrogen bonds. Hydrogen bonds are broken by an enzyme and DNA polymerase makes a complementary strand of each parent strands. DNA polymerase moves along the strand of DNA, and uses the bases as a template to make a new strand of DNA. It matches A with T and G with C as it moves along the strand. DNA liagase is the glue that seals any gaps holding the new strand together. DNA polymerase proof reads its work and corrects any mistakes it finds. If a mistake goes uncorrected the error will become a mutation, c...

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...get pregnant. If the other partner is a carrier too then the baby will express the disorder.

References

Evans-Martin, F. (2009). Genes and Disease Down Syndrome. New York, New York. Chelsea House, Infobase publishing

Martini, H., Nath, J., & Bartholomew, E., (2012). Fundamentals of Anatomy and Physiology 9th edition, California, Pearson Publishing

Massimini, K. (2000). Genetic Disorders sourcebook 2nd edition, Michigan, Omnigraphics

Mayoclinic staff. (Aug 17, 2010). Triple X Syndrome. Retrieved from http://www.mayoclinic.com/health/triple-x-syndrome

Santrock, J. (2011). Life-Span Development 13th edition, New York, New York. McGraw-Hill

Starr, C., Evers, C., & Starr, L. (2009). Biology Today and Tomorrow with Physiology. Mason, Ohio. Cengage Learning

Trisomy 18 foundation. (2010). Trisomy 18. Retrieved from http://www.Trisomy18.org