As of September 30, 2005, the North Central Regional Technology in Education
Consortium is no longer in operation.
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:
- 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).
- 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.
- 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.
- 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.
- 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:
- Each student should have their completed karyotype from Activity One
- Scissors for each students
- Scotch tape
- A colored marker for each student (each pair will need two different
colors)
- Coin or dice
- A blank karyotype form without chromosomes
Lesson:
- Once again, ask the students pair off.
- Have students color the chromosomes on their karyotype one color, but make
sure it differs from the color their partner chose.
- 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):
A. With a diagram of meiosis
(an Adobe Acrobat version of this diagram is also
available) handy for reference, roll the dice or flip a coin to determine
which chromosome from a given pair will be passed onto the child. (Example:
odd on dice = chromosome on left; even on dice = chromosome on right.) Cut
out that chromosome, being careful to also cut out the symbols for the genes
the students put on the chromosomes. (This simulates Meiosis 1 for that pair
of chromosomes).
B. Cut that doubled chromosome in half and place one of the pieces on the
karyotype in the corresponding blank. Your "mate" should do the same thing,
resulting in a pair of single separate chromosomes, one from "mom" and one
from "dad." (This simulates Meiosis 2.) Refer to "Virtual
Meiosis," (http://www.biology.uc.edu/vgenetic/meiosis/prophase1.htm)
C. Continue this process for every pair of chromosomes until a "baby" is
produced with 23 pairs of single chromosomes.
- 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:
- 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.
- 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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