Download Hairy Heredity - Oklahoma 4-H

Hairy Heredity
Skills:
Life Science, Math
Objective: Students will flip coins to demonstrate how parents pass genetic
traits to their offspring through heredity and the difference between dominant
and recessive genes, and how they interact.
Background
Agriculturalists have pioneered the study of genetics and heredity. For
centuries farmers and ranchers have selected plant varieties and livestock for
specific traits. Plant breeders select plant varieties which produce more seed
or fruit. Livestock producers select animals with specific traits such as
increased milk production, ample muscle mass or structural correctness.
Selecting for these traits has allowed agriculturalists to produce a higher
quality and more abundant food supply.
Heredity is the passing on of traits from parents to offspring. Most plants
and animals have two of every kind of gene, one from their mother and one
from their father. Only one gene from each parent is passed to each offspring
for a particular trait. There are different forms of a gene that are referred to
as alleles. Alleles are forms of the same gene with small differences in their
DNA sequence. These small differences contribute to each person's unique
physical features. Some alleles are dominant while others are recessive.
Dominant genes overpower recessive genes and are always expressed in
offspring. Recessive genes are only expressed in offspring if both parents
contribute a recessive gene. In human eye color, the gene for brown eyes is
dominant and the gene for blue eyes is recessive. Therefore, if the offspring
receives a brown eye gene from either parent, the offspring will have brown
eyes. The offspring would have to receive a blue eye gene from each parent
to have blue eyes.
The following diagram is a Punnett square which illustrates all the possible combinations of two gene sets Bb and Bb and the resulting genetic traits.
B is the dominate gene for Brown eyes b is the recessive gene for Blue eyes.
Punnett square boxes show the possible combinations of genes that an offspring may receive from its parents.
Punnett Square
Bb X Bb
Parent’s Eye Color
B 6 (Brown Gene)
b 6 (Blue Gene)
B (Dominant Trait) 4
BB = Brown Eyes
Bb = Brown Eyes
b (Recessive Trait) 4
Bb = Brown Eyes
bb = Blue Eyes
http:www.agclassroom.org/ok
P.A.S.S.
Grade 5
Science Process—2.1;
4.1,2; 5.3
Math—2.1cd,2a
Grade 6
Science Process—2.1;
4.1,2; 5.3,4
Math Process—1.6; 2.1;
4.1
Math —5.1
Grade 7
Science Process—2.1; 4.1;
4.2; 5.3
Life Science—3.1, 2
Math—2.2c; 5.1,3
Vocabulary
agriculturalist—someone
involved in the science, art, and
business of cultivating the soil,
producing crops and raising
livestock.
allele—one of two or more
alternative forms of a gene that
controls the same inherited
characteristic.
DNA (deoxyribonucleic
acid)—molecule that contains
genetic information and is
located in the nucleus of every
cell inside an organism.
gene—The basic unit of heredity that serves as a blueprint for
each protein product produced
in the human body; humans
have over 30,000 genes.
heredity—the passing on of
traits from parents to offspring.
Punnett Square—diagram
used by scientists to help them
to figure out how inherited
traits (characteristics) will be
distributed.
trait—an inherited distinguishing feature or characteristic of
an organism.
Probability is the chance that something will happen. Using the
above Punnett square box, there is a 75 percent chance of an offspring
having brown eyes if both parents have both dominate and recessive
genes. There is a 25 percent chance of the offspring having blue eyes.
This simple illustration demonstrates how the genetics of one gene
functions. Humans, plants and animals have multiple genes which
have complex interactions to determine offspring traits.
Math and Science
1. Brainstorm to find student knowledge of the transfer of genetic
traits from parents to offspring. Share background material.
2. Give each student a copy of the activity worksheet and a coin.
—Instruct students to flip the coin to determine which traits the
mother will pass on to her offspring. If the coin lands on heads, the
students should circle the dominant trait. If the coin lands on tails,
the students should circle the recessive trait.
—Have students repeat this process for all eight traits from the
mother and father.
—Once all the traits have been randomly selected from the mother
and father, transfer the selected traits to the Genetic Trait
Worksheet.
—Circle the appropriate genetic trait which will be expressed in the
offspring.
3. Hand out the “Smiley Face Worksheet,” and have students draw
and color a smiley face that expresses all the randomly selected
genes.
—Are all the faces the same? How are the faces different? Why?
—Count across the room the number of smiley faces with brown
eyes. Is it 75 percent of the faces, as the Punnett Square predicted?
Do the same for the other traits.
4. Repeat the genetic activity and compare the results with this activity. Are the results the same? Is the percentage of blue eyes the
same? Other traits?
5. Develop a Punnett square diagram for the other traits. Why is there
a 50 percent chance of the offspring being a girl?
6. . Compare student’s characteristics around the room. Do 75 percent of the students have brown eyes? What percentage of student’s
eyes are blue or green?
Oklahoma Ag in the Classroom is a program of the Oklahoma Cooperative
Extension Service, 4–H Youth Development, in cooperation with the
Oklahoma Department of Agriculture, Food and Forestry and the Oklahoma
State Department of Education.
Oklahoma Ag in the Classroom
Oklahoma 4-H Programs
205 4-H Youth Development
Oklahoma State University
Stillwater, OK 74078
405-744-8889 http://www.agclassroom.org/ok
http://www.agclassroom.org/ok
Hairy Heredity
Name ______________________________________________________________
Use the flip of a coin to determine which genes your offspring will carry. Flip a coin to determine which genetic traits each parent will pass on to their offspring. If the coin flip lands on
heads select the dominate trait. If the coin lands on tails, select the recessive trait.
FATHER’S TRAITS
MOTHER’S TRAITS
Flip coin and circle selected trait.
1. face shape
heads
tails
dominant recessive
R
s
1. face shape
B
b
3. eye color
4. mouth shape
S
f
6. skin color
Y
2. eye shape
3. eye color
5. nose shape
7. hair
8. male/female
R
B
H
X
o
2. eye shape
heads
tails
dominant recessive
R
R
s
o
B
b
4. mouth shape
S
f
o
6. skin color
Y
o
X
8. male/female
l
b
5. nose shape
7. hair
B
H
X
Produced by Oklahoma Cooperative Extension Service, Division of Agricultural Sciences and Natural Resources, OSU, inn cooperation with the
Oklahoma Department of Agriculture, Food and Forestry and the Oklahoma State Department of Education, 2005.
l
b
Y
Genetic Trait Worksheet
Name ______________________________________________________________
sample trait
1. face shape
2. eye shape
3. eye color
4. mouth shape
5. nose shape
6. skin color
mother’s
traits
T
father’s
traits
t
possible trait combinations
Circle appropriate trait.
tall
TT
round
RR
8. male/female
short
tt
round
Rs
square
ss
brown
BB
brown
Bb
blue
bb
big
BB
big
Bl
round
RR
smile
SS
round
Ro
oval
oo
smile
Sf
frown
ff
yellow
YY
yellow
Yo
orange
oo
male
Xy
female
XX
n/a
hairy
HH
7. hair
tall
Tt
hairy
Hb
Produced by Oklahoma Cooperative Extension Service, Division of Agricultural Sciences and Natural Resources, OSU, inn cooperation with the
Oklahoma Department of Agriculture, Food and Forestry and the Oklahoma State Department of Education, 2005.
little
ll
bald
bb
Smiley Face Worksheet
Name ______________________________________________________________
1. face shape
round / square
Draw and color the offspring’s smiley face
Add details to identify your smiley as a boy or girl.
2. eye shape
round / oval
3. eye color
brown / blue
4. mouth shape
smile / frown
5. nose shape
big / little
6. skin color
yellow / orange
7. hair
hairy / bald
8. male/female
boy / girl
offspring’s name____________________
Produced by Oklahoma Cooperative Extension Service, Division of Agricultural Sciences and Natural Resources, OSU, inn cooperation with the
Oklahoma Department of Agriculture, Food and Forestry and the Oklahoma State Department of Education, 2005.