TITLE:  MENDELIAN GENETICS
 
 GRADE LEVELS: 9-12
 
 INTRODUCTION:
 
      Gregor Mendel was a monk who was born in 1822 in what was once
 Austria. At the age of 21 he entered a monastery in the town of Brno. 
 This monastery was a center of scientific learning in Europe at the time. 
 Mendel was sent to the University of Vienna for two years to study science
 and mathematics.  When he returned to the monastery he was assigned the
 duties of teaching high school in the town of Brno and keeping the
 monastery garden.  It was in this garden where Mendel conducted his famous
 genetics experiments with pea plants.  His observations of how traits are
 inherited in peas, combined with his knowledge of the mathematical
 principles of probability, led to his discoveries about the inheritance of
 genetic traits.  These discoveries revolutionized biological science. 
 
      Mendelian genetics is a major topic covered in most high
 school Biology classes.  Students in these classes usually conduct
 experiments that demonstrate the principles of genetics, but these
 experiments are conducted with small numbers of organisms or
 objects that represent organisms.  Expected genetic ratios from a
 particular cross may not show up when only a few organisms or
 items are observed.  The larger the samples examined, the closer
 the numbers will be to the expected ratios.
 
      To test the hypothesis that the larger the number of organisms
 or items considered in a genetic cross, the closer the number will
 be to the expected ratios, an experiment in which high school
 classes from throughout the nation participate and submit data 
 from the results of the experiments can be conducted and the total
 data compiled.

 PREREQUISITES FOR PARTICIPATION:
 
 Prior to participation in this experiment, students should:
 
 1. study Mendel's laws of genetics:  heredity is controlled 
    by genes and genes occur in pairs; the law of dominance 
    and recessiveness, the law of segregation, and the law of
    independent assortment.  
 
 2.  be familiar with genetics terminology; i.e.:  homozygous,
     heterozygous, allele, etc.
 
 2. study the use of Punnett squares to observe the principles
    of genetics that are based on Mendel's work.
 
 3. study one-factor crosses that demonstrate the important role
    probability plays in the study of genetics.
 
 THE EXPERIMENT:  Simulation of a one-factor cross.
 
 LEARNER OUTCOMES:  The students will simulate a one factor cross
 to demonstrate Mendel's laws of inheritance.
 
 MATERIALS:  2 disks (coins may be used)
             masking tape
             paper cup
 
 BACKGROUND INFORMATION:  In guinea pigs, rough coat (R) is dominant
 over smooth coat (r).  The capital letter R is used to represent
 the dominant allele for rough coat and the lower case letter r is
 used to represent the recessive allele for smooth coat.  The
 parents in this cross are both heterozygous for the traits (Rr).
 To facilitate submission of data, only one cross will be
 considered.
 
 PROCEDURE:  
 
 STUDENTS MAY WORK ALONE, IN PAIRS, OR THE WHOLE CLASS MAY PERFORM
 THE EXPERIMENT TOGETHER.
 
 1.  Cut 4 pieces of masking tape large enough to cover the sides
     of the disks.
 2.  On one side of each disk, write R and on the other side write
     r.  One disk will represent the alleles of the male parent, the
     other the alleles of the female parent.  
 3.  Place the 2 labeled disks into the paper cup.  Shake the cup so
     that the coins are tossed.  Empty the cup onto the top of your
     desk.  Record the results of the toss on your data table.  The
     tossing of the coins demonstrate the law of segregation during
     gamete formation and recombination during fertilization.
 4.  Toss the disks a total of 40 times, recording the results in
     your data table.  (See example of data table below).
 5.  If students are working individually or in pairs, total the
     class results.  Alter numbers on data table as necessary.
 6.  Submit results via e)mail to <name@address> by <date>.
 
              DATA TABLE FOR INDIVIDUAL RESULTS
 =================================================================
 PHENOTYPES |GENOTYPES| NO. EXPECTED |  TOSS RESULTS | TOTAL NO. |
            |         | FOR 40 OFF)  |               | OBSERVED  |
            |         | SPRING       |               | FOR 40    |
            |         |              |               | OFFSPRING |
 =================================================================
 homozygous |   RR    |     10       |               |           |
 rough      |         |              |               |           |
 =================================================================
 heterozygous|  Rr    |     20       |               |           |
 rough       |        |              |               |           |
 =================================================================
 homozygous |   rr    |     10       |               |           |
 smooth     |         |              |               |           |
 =================================================================
 
 EVALUATION:  In written or oral form, check for understanding of
 genetics principles and probability by discussing the results of
 the experiment as a class, then compare these results to the final
 results after the data has been compiled. 

 TIMELINE:
 
 ONE OR TWO MONTHS BEFORE EXPERIMENT BEGINS:  Announce the
      newton.dep.anl.gov or 130.202.92.50, login: 'cocotext').
 
 WEEKS 1 AND 2:  Introduce students to Mendelian genetics and 
                 mathematical principles of probability.
 
 WEEK 3:  Conduct experiment, submit data to <name@address>.
 
 WEEK 4:  Data will be compiled by host class.
 
 WEEK 5:  Post results in newsgroups and send results individually
          to participants.
 
 FOLLOW UP:  
        Collaborate in solving different genetics problems.
 
        If questions remain unanswered or new questions arise
        post messages in NEWTON BBS in "Ask a Scientist a Question."
        A scientist in the field will post the answer or an
        explanation.

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