Download Arthropod Genetics

B
I
O
L
O
G
Y
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
Arthropod
Genetics
by Sharon Zumwalde
T
hink about invertebrates for a minute.
Do arthropods come to mind? The
phylum Arthropoda is the most diverse
of the invertebrates, spanning from horseshoe
crabs to lobsters to insects. These organisms
have in common their exoskeletons, segmented
bodies, and jointed limbs. I take advantage of
the phylum’s diversity to spark students’
creativity and problem-solving skills, during a
review and application activity in which
students build their own arthropods and predict
the traits of their imaginary offspring.
I use this activity after teaching back-to-back
units on arthropods and genetics in my seventh
grade life science class. In the multi-step review,
students
1. Construct imaginary arthropods.
2. Select dominant and recessive traits along
with genotypes and phenotypes for their
imaginary arthropods.
3. Construct Punnett squares showing possible
gene combinations from the cross of two
imaginary arthropods.
4. Determine traits of the offspring and
construct sample specimens.
20
science scope
February 2000
To do this activity, students must first have a
solid grounding in arthropod classification, basic
genetics vocabulary, and problem-solving with
Punnett squares. Students must understand
dominant and recessive genes, genotypes and
phenotypes, and purebred and hybrid
(homozygous and heterozygous) traits. This
activity spotlights the ability to apply and work
with given genetic information. It combines
creativity and hands-on construction with the
concepts of classification and genetics.
Setting up
Figure 1 shows a list of suggested materials for
building arthropods, but you can use whatever is
available as long as specific materials are
designated for dominant and recessive forms of
each trait. For example, I assign toilet paper rolls
as a dominant body trait, and paper cups as a
recessive body trait. Likewise, wax paper
represents a dominant wing form, while foil is a
recessive form. I keep materials for each body
Sharon Zumwalde is a seventh grade life science
teacher at Milford Junior High in Milford, Ohio.
○
○
○
○
○
○
○
○
B
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
part in separate boxes, and have students pick
what materials they will use from the boxes.
Spiders and beetles and crabs, oh my!
To start off, I provide students with the
worksheet on page 23. Students can work
individually or in pairs to create their animals. I
use slips of paper to randomly assign students to
specific divisions of Arthropoda, to ensure
variety in the resulting menagerie. I also tell
students to keep their assignments secret
throughout the building stage, so that later other
students can practice classifying their classmates’
animals. Construction usually takes at least one
science class period.
Once students’ creative ideas have come to
fruition, it’s time to do some analysis. I reveal
which materials represent dominant traits and
which are recessive, and then students record
the genotypes and phenotypes of their animals’
traits. In the case of dominant traits, I allow
students to choose whether they want them to
be purebred or hybrid.
Once the genotype and phenotype is
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
I
O
L
O
○
identified and recorded for each trait, students
can “mate” their creations with the other
creatures. To prepare for the event, students first
identify and record the genotypes and
phenotypes of the potential mate, and then
construct Punnett squares showing the
offsprings’ possible gene combinations for each
trait (see page 23). Students also need to
identify the phenotype of each genotype within
the Punnett square and determine if each trait is
purebred or hybrid. From this information
students can compile a list of possible genotypes
and phenotypes for offspring of the pairing and
apply their creativity once again to construct
sample offspring.
For assessment, I assign 10 points to each
phase of the project: Arthropod Construction,
Mapping the Family Genes, Punnett Squares,
and the Offspring, for a total of 40 possible
points. I check that students construct their
arthropods correctly (see Figure 2), and I also
assess students’ ability to correctly identify the
genotype, phenotype, hybrid, and purebred
nature of their creations.
PHOTO COURTESY OF THE AUTHOR
○
Some of the many arthropods created by students.
February 2000
science scope
21
G
Y
B
I
O
L
O
G
Y
○
○
○
○
○
○
○
○
○
FIGURE 1
Body
Legs
Eyes
Antennae
Wings
FIGURE 2
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
Dominant
toilet paper rolls (AA, Aa)
plastic cups (BB, Bb)
Styrofoam egg cartons (CC, Cc)
popsicle sticks (DD, Dd)
colored straws (EE, ee)
colored pipe cleaners (FF, Ff)
white buttons (GG, Gg)
colored Styrofoam peanuts (HH, Hh)
blue pom-poms (II, Ii)
white twist ties (JJ, Jj)
Q-tips (KK, Kk)
paper clips (LL, Ll)
coffee filters (MM, Mm)
waxed paper (NN, Nn)
Construction checklist
Ten points awarded if all body parts are
present and correct, 8 points if one is missing
or incorrectly placed, 5 points if more than
one is missing or incorrect.
science scope
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
Materials list: genotypes and phenotypes
Chilopoda (centipedes)
____ 1 pair of legs per body segment
____ poisonous jaws (student’s choice of
materials)
____ 1 pair of antennae
Diplopoda (millipedes)
____ 2 pairs of legs per body segment
____ 1 pair of antennae
Crustacea (shrimp, lobsters, crabs)
____ 5 pairs of legs ____ attached to fused
head/thorax
____ 2 pairs of antennae
Arachnida (spiders, scorpions)
____ 2 body parts (head and thorax)
____ 4 pairs of legs
Insecta (ants, beetles, dragonflies)
____ 3 body parts (head, thorax, abdomen)
____ 3 pairs of legs ____ attached to thorax
____ one pair of antennae
____ wings (optional)
22
○
February 2000
Recessive
Styrofoam balls (aa)
paper cups (bb)
cardboard egg cartons (cc)
coffee stirrers (dd)
white or striped straws (ee)
white pipe cleaners (ff)
colored buttons (gg)
white Styrofoam peanuts (hh)
colored pom-poms (ii)
colored twist ties (jj)
toothpicks (kk)
short pipe cleaners (ll)
cellophane paper (mm)
foil (nn)
Extensions
This activity easily lends itself to cross-curricular
teaching. In language arts class, students can
1. Name their animals and write a descriptive
paragraph on their habitat, food, predators, and
structural adaptations.
2. Identify and describe possible characteristics
for a third generation of arthropods, based on
the second-generation offspring.
3. Propose changes in their animals’
environment and describe how their animals
might adapt to those changes. For instance,
• a drought may occur,
• a foreign species that shares the same food
source as the animal may be introduced into the
habitat,
• a predator may be introduced into the habitat, or
• the habitat may be destroyed by pollution or
human development.
In any case, students will learn that thinking
creatively and critically go hand in hand. You
and your students will enjoy making the
connections between bugs and genes.
Acknowledgements
This activity is adapted from a workshop presented
by Beryl Stoddard at the 1997 NSTA Convention in
New Orleans: “The Genetics and Adaptations of
Artful Arthropoda.”
○
○
○
○
○
○
○
○
B
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
○
I
O
L
O
○
Building arthropods
Arthropod construction
Build an arthropod by selecting one material for each characteristic: body segments, legs, eyes, and
antennae. Do not mix white and colored materials. Give your creature the characteristics of your
assigned arthropod, but be creative too!
Materials
Body: egg cartons, toilet paper rolls, Styrofoam balls, paper and plastic cups
Legs: straws, popsicle sticks, coffee stirrers, pipe cleaners, plastic straws
Eyes: buttons, Styrofoam peanuts, chenille pom-poms
Antennae: twist ties, Q-tips, toothpicks, paper clips, short pipe cleaners
Wings: waxed paper, coffee filters, foil, cellophane paper
Mapping the family genes
Your arthropod
Phenotype
Genotype
Another arthropod
Phenotype
Genotype
Body
Legs
Eyes
Antennae
Wings
Punnett squares
Make a Punnett square for each of the characteristics above to show the cross between two parent
arthropods. Be sure to indicate both the genotype and phenotype of all traits. Also identify the traits
as either purebred or hybrid.
Body
Legs
Eyes
Antennae
Wings
The offspring
Using the information from your Punnett squares, select traits to include in a sample offspring.
Record the phenotypes and genotypes of your offspring’s traits in the chart below. Build your sample
offspring using the materials provided.
Phenotype
Genotype
Body
Legs
Eyes
Antennae
Wings
February 2000
science scope
23
G
Y