Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Blue People of Kentucky Genetic Research Activity Name ____________________________________ Period ___________________________________ Background: In normal blood hemoglobin is an abundant protein that carries oxygen. Some of the hemoglobin is in an altered form called methemoglobin. Methemoglobin is converted to hemoglobin by an enzyme called cytochrome b5 reductase. In people with methemoglobinemia the enzyme is not functioning properly and they have too much methemoglobin in their blood which gives their skin a bluish color. There are several causes of methemoglobinemia. The most common is acquired by exposure to chemicals like benzene or certain antibiotics. Even infants that eat too many beets can turn a blue color. It disappears when the chemicals are gone. The Fugates had an inherited form of the disease. Oddly enough, the treatment for the disease was a blue dye called methylene blue. When given a small dose the patients’ skin became normal. Genetics: http://www.nclark.net/Pedigree.gif Look at the Pedigree and Answer the related questions: 1. Martin Fugate had 7 children, 4 with blue skin. Some records indicate that Martin had blue skin. According to the pedigree was his skin blue or normal? 2. What is a possible explanation for why Benjy Stacy was blue at birth even though he is heterozygous for the trait? 3. Why weren’t any of John and Luna’s 13 children blue? The Central Dogma of Biology: DNA mRNA Protein 4. What was the name of the enzyme that changed methemoglobin into hemoglobin? In the Fugate family the genetic disorder was methemoglobinemia type I, a form of the condition that has no apparent effects other than blue skin. Go to the web site: http://omim.org This website, Online Mendelian Inheritance in Man, is a database of human genes and genetic disorders. Look up the disorder by using either the name of the enzyme or the name of the disorder and answer the remaining questions. You may have to read some descriptions and make a decision about which link to choose. 5. What is the location of the gene that codes for this enzyme? 6. On which chromosome is it found? 7. The gene of interest is a section of DNA that codes for the enzyme cytochrome b5 reductase. Enzymes are proteins that are made of chains of amino acids. Methemoglobinemia type I is the result of a substitution mutation that results in one amino acid being changed to another. In OMIM search using: CYTOCHROME b5 REDUCTASE 3 Read through some of the material and find a possible amino acid switch and identify the amino acids involved. Use the amino acid abbreviation chart provided. There are several possibilities; be sure to correctly match the mutant amino acid to the original normal amino acid. These variants show that a different mutation can affect the same gene and may change how that gene is expressed. a. Normal Amino Acid ____________________________ b. Mutant amino acid _____________________________ Amino Acid abbreviation chart: A similar chart can be found here: http://mendel.ethz.ch:8080/Server/ServerBooklet/_17545_tabular870.gif