Genetic Diseases Pattern of Inheritance

Course Outline 

V.  Basic Patterns of Human Inheritance    

     A.  Recessive Genetic Disorders         

         1.  Cystic fibrosis         

         2.  Albinism         

         3.  Tay-Sachs disease         

         4.  Galactosemia         

         5.  Phenylketonuria     

    B.  Dominant Genetic Disorders         

         1.  Huntingdon’s disease        

         2.  Achondroplasia    

   C.  Pedigrees    

   D.  Analyzing Pedigrees         

        1.  Infering genotypes         

        2.  Predicting disorders   

   E.  Complex Patterns of Inheritance        

        1.  Incomplete Dominance        

        2.  Codominance              

             a.  Sickle cell disease              

             b.  Sickle cell disease and malaria        

        3.  Multiple alleles             

             a.  blood groups in humans             

             b.  Coat color of rabbits         

        4.  Epistasis        

        5.  Sex determination        

        6.  Dosage compensation        

        7.  Sex linked traits             

            a.  Red and green color blindness             

            b.  Hemophilia        

        8.  Polygenic Traits        

        9.  Environmental influences 

      10.  Twin Studies  

    F.  Chromosomes and Human Heredity        

        1.  Karyotype studies        

        2.  Telomeres        

        3.  Nondisjuction             

             a.  Down syndrome             

             b.  Sex chromosomes        

        4.  Fetal Testing

Teaching Aids

1.  Computer

2.  Smart Board

3.  Powerpoint

4.  Paper for students to use to make a foldable.  Fold a sheet of notebook paper lengthwise, leaving a half inch between the folds as shown.  Rotate the paper and cut the top layer to form eight tabs of equal size.  Label each tab with the name of a different genetic disorder.  Under the tabs, write about each disorder.

5.  Vocabulary sheet with fill in the blanks for each student.  Vocabulary words are incomplete dominance, codominance, recessive genetic disorders, dominant genetic disorders, multiple alleles, epistasis, sex determination, sex chromosomes, chromosome inactivation, dosage compensation, sex linked traits, polygenic traits, karyotype, telomere, nondisjunction, monosomy, trisomy and fetal testing.

Class Projects

Students will collect data about the genetic diseases and provide the following information:  Disorder, Occurence in the U.S., Cause, Effect, Cure/Treatment, Pattern of Inheritance.  These items should be listed in a table on a poster board.  The diseases to be examined are cystic fibrosis, hemophilia, sickle cell anemia, Down's syndrome, Tay-Sach's disease, color blindness, and phenylketonuria.

Review Questions
1.  Which term describes a person who is heterozygous for a recessive disorder?

2.  Which condition is inherited as a dominant allele?

                a.  albinism                                       b.  cystic fibrosis

                c.  Tay-Sachs disease                        d.  Huntingdon's disease 

3.  Which is not a characteristic of a person with cystic fibrosis?

       a.  chloride channel defect                      b.  digestive problems

       c.  lack of skin pigment                           d.  recurrent lung infections

4. _____________ is an inheritance pattern in which the heterozygous genotype results in an intermediate phenotype between the dominant and recessive phenotype.

5.  A characteristic that has more than one pair of possible traits is said to be a(n) _____________.

6.  Genes found on the sex chromosomes might be associated with _____________.


Once students learn about genetic diseases they may have more questions about genetic testing.  Tell them to check out this website 

Other Useful Information

Many times with the study of Genetic Diseases, students want to learn more about how to prevent them.  Let them do a report on fetal testing.  The students can choose between amniocentesis, chorionic villus sampling, and fetal blood sampling.  The report should provide information about the benefits and risks of testing.