Dominant & Recessive Genetic Disorders & PedigreesDominant & Recessive Genetic Disorders & Pedigrees

March 18, 2009March 18, 2009

Turn in your portfolio to the class manager.Work with your laboratory group members to

answer questions 1-7 in the packet provided.

All other answers only received one vote.

In 1903, an American biologist, Walter S. Sutton observed chromosomes behaving as Mendel described his “factors.”

Outlined the chromosome theory of heredity.

Incidentally, Walter Sutton also played on the first ever organized collegiate basketball team at the University of Kansas in 1899.First basketball team at the University of Kansas, 1899. Walter is 3rd from the left, back row and Naismith is on the far right. Walter's brother, William, and team captain, is 3rd from the left, middle row (Taft, 1941).  (Courtesy of Clendening History of Medicine Library, University of Kansas Medical Center)

At the conclusion of this lesson students should be able to:Identify and distinguish between recessive and

dominant inheritance patterns.Interpret a pedigree.Construct a pedigree using self-obtained data.

Only expressed in an individual who is homozygous for the recessive alleles

Heterozygous individuals can be carrierscarriers – do not show the trait, but can pass the allele to their children

Examples:AlbinismCystic fibrosisTay Sachs diseaseGalactosemiaAlkaptonuria

One dominant allele in an individual’s genotype causes the disease.

There are no carriers.Examples:

Huntington’s diseaseAchondroplasia

Studying human genetics can be difficult.Humans reproduce and mature slowly.Most humans do not know their genotypes.Humans cannot be made to have offspring or

made to have them with a specific partner (unethical).

Most of our knowledge of human genetics comes from studying patterns of heredity in family trees and family histories.

Scientists use pedigreespedigrees – diagrams that trace the inheritance of a particular trait through several generations.

Genotypes are inferred from phenotypes.Entire families are analyzed.Pedigrees can help genetic counselors

determine dominant and recessive inheritance patterns.

One trait is analyzed at a time.Dominant traits are easier to identify than

recessive traits.Relies on accurate record-keeping and in some

cases multiple family members undergoing genetic testing.

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"Autosomal Dominant Pedigree Chart." Wikimedia Commons. 13 Feb 2009. 17 Mar 2009 <http://commons.wikimedia.org/wiki/File:Autosomal_Dominant_Pedigree_Chart.svg>.

Biggs, Alton, et. al. Biology. New York: The McGraw Hill Companies, Inc., 2007.

Nelson, MD, Stanley R. & Peter S. Nelson MD. "Biology and Basketball at the University of Kansas." Walter Sutton's Chromosome Theory of Heredity: One Hundred Years Later. 17 Mar 2009 <http://www.kumc.edu/research/medicine/anatomy/sutton/biology_and_basketball.html>.

Tissot, Robert. "Mendelian Inheritance - Pedigree construction." Human Genetics for 1st Year Students. 18 Mar 2009 <http://www.uic.edu/classes/bms/bms655/lesson3.html>.