As of September 30, 2005, the North Central Regional Technology in Education Consortium is no longer in operation.
NCRTEC Professional Development Planning and Evaluation Teaching and Learning

Major Learning Activities

Activity One:
This activity takes approximately one class period, or approximately 60 minutes. The student product from this activity will be used in Activity Two.

Materials:
Human karyotypes (one for each student in your class--equal numbers of normal male and female karyotypes)

Internet Web site: The Amazing Picture Machine (http://www.ncrtec.org/picture.htm)

Lesson:

  1. Have students pair off and provide them with a normal male and female karyotype. (The pairs need not consist of one male and one female. If you have an uneven number of students, you can have a single student work with both a male and a female karyotype or you can have three students work together so that two act as parents and the third helps with data collection).

  2. Have each student determine their own phenotype for each of the traits listed in Table 1. To help with this process, refer to the pictures for these phenotypes on The Amazing Picture Machine (http://www.ncrtec.org/picture.htm). It can be very difficult to explain each of these traits to your students. The pictures make this process go quickly and more smoothly so that they are not distracted from the intent of the lesson.

  3. The students should then determine their genotype that produced their phenotype. (Note: For a dominant phenotype, the genotype could be heterozygous (Rr) or homozygous (RR).) For this activity, have the students flip a coin or roll a dice to determine which of the two genotypes they should use.

  4. Next, the students should locate each gene pair on the appropriate chromosome (see Table 1) in their human karyotype. For example, if they are heterozygous (Rr) for the trait on chromosome pair 22, they should label one of the chromosomes with "R" and the other chromosome with "r." Since these chromosomes have gone through duplication in preparation for division, they will each have two identical letters (allele) for that gene.

  5. Tell students that it is estimated that we all carry between six and nine lethal recessive genes. Ask them to assume they are all carrying (heterozygous) the recessive disorders in Table 2. Have them assign their genes to the appropriate chromosome as they did earlier.

TABLE 1

Trait Chromosome for Gene Location Dominant Phenotype Possible Dominant Genotypes Recessive Phenotype Recessive Genotype
color of iris 2 not blue EE or Ee blue ee
widow's peak 4 peak PP or Pp no peak pp
cheek dimples 5 dimples DD or Dd not dimples dd
face freckles 9 freckles FF or Ff no freckles ff
mid-digital hair 10 hair HH or Hh no hair hh
Hitchhiker's thumb 17 straight TT or Tt curved tt
Hallux length (toes) 20 long 2nd toe BB or Bb long big toe or = to 2nd toe bb
ear lobes 21 free LL or Ll attached ll
tongue rolling 22 ability RR or Rr no ability rr
cleft chin 16 cleft YY or Yy no cleft yy

There is some controversy as to whether the above traits are simple monohybrid traits. Whether they are or not, they work well in both stimulating student interest and helping students conceptualize this process. Because we do not know the actual location of the genes, I have arbitrarily assigned them to a chromosome pair.

TABLE 2
Trait Chromosome for Gene Location Genotype
skin cancer 1 Cc
cystic fibrosis 7 Qq
albinism 11 Aa
xeroderma pigmentosa 15 Xx
lung cancer 3 Nn
PKU (phenylketonuria) 12 Gg
Muscular Dystrophy X sex chromosome Mm (girls only)

Activity Two:
This activity should take one class period, or about 60 minutes. The product of this activity may be used in Activity Three.

Materials:

Lesson:
  1. Once again, ask the students pair off.

  2. Have students color the chromosomes on their karyotype one color, but make sure it differs from the color their partner chose.

  3. Tell students to cut out and put their chromosomes onto their "baby's" karyotype, along with the chromosomes from their "mate" by doing the following (meiosis simulation):

  4. While your students are working on the karyotype for their "baby," you can assume the role of Mother Nature and create some chromosomal mutations, such as nondisjunctions, by adding or removing a chromosome from their "child's" karyotype. You could produce conditions such as Down's Syndrome, Turner Syndrome, Klinefelter Syndrome, trisomy 13, or trisomy 18.

    Activity Three:
    This activity should take one class period, or about 60 minutes.

    Materials:
    Baby's karyotype produced in Activity Two

    Lesson:

    1. While working in pairs, have the students determine their "child's" genetic makeup (genotype) and physical appearance (phenotype) for each of the traits described in Activity One. They should record these in a chart of their own design.

    2. Some of the extra or added recessive traits the students were all carriers for in Activity One may appear in their offspring in Activity Three. Most of these may be conditions students never heard of before today. But as "parents," they will be concerned to find out more about these conditions, as well as the conditions you created by adding or removing chromosomes. Ask the students to think carefully before responding to the following question: As the parents of this child, what questions would you like to ask your doctor and your genetic counselor?

    Activity Four: The time for this activity will vary depending on how much time you wish to spend on it and to what extent you would like your students to work.

    Materials:
    Access to the Web and other resources dealing with genetic disorders

    Lesson:
    In this activity, students will change their roles. Instead of being a parent, they will role-play as a genetic counselor who will find the answers to the questions they wrote as the parent of the child in Activity Three. Have the students research the questions they raised as parents. They have ownership of these questions and should be motivated to find out what the future holds for their "child."

    The Web has an overwhelming amount of information dealing with genetic disorders. It may be helpful to bookmark some Web sites to save your students time when you have a limited number of computers linked to the Internet.

    Some resources on the Web would include:

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