Download Smiley Babies: Genotype and Phenotype

Smiley Babies: Genotype and
Phenotype
February 18, 2014
Welcome! 2/18/14
Students will:
q  Distinguish between genotype and phenotype
q  Demonstrate that traits are passed from parents to
offspring in random assortment
By completing the “Genetics with a Smile” lab.
Catalyst:
1.  What is a trait?
2.  Describe YOUR traits! Include at least
10 traits.
Homework
—  Unit
3-4 Blue Folder DUE TODAY
—  Signed Biology Check-In DUE TODAY
**Deadlines extended due to Snow Days
—  HW
5.1 DUE Friday, 2/21/14
—  TODAY—Lab Makeup Day
◦  Strawberry DNA Extraction Lab
◦  Flower Dissection Lab
Catalyst
—  What
is a trait?
—  What are some of our traits?
Genes and Alleles
—  Genes
are specific pieces of DNA that
code for traits
—  Alleles are different forms or variations
of a trait on a gene
—  You have two alleles of each gene—one
from mom and one from dad!
◦  For example: Eye color could be brown (B)
or blue (b). Maybe you get a (B) from your
father, and a (b) from your mother…
◦  Another example is A, B, or O blood type.
Meiosis and Fertilization
—  Meiosis
makes gametes, with half the
number of chromosomes
—  They are combined during fertilization,
making a full UNIQUE set of DNA
Determining Genotype and
Phenotype
—  Genotype
is the genetic makeup—what
do the genes say?
—  Phenotype is the physical makeup—what
do the traits look like?
Genotype and Phenotype Example
Dominant and Recessive
—  A
dominant trait is EXPRESSED or SEEN
—  A recessive trait is NOT expressed or
NOT SEEN
◦  For example, blue eyes (b) was recessive and
brown eyes (B) was dominant
Incomplete Dominance
—  Occasionally, genes
don’t follow the basic
rule of dominant/recessive—showing one
OR the other—and make a mixture!
—  This is called incomplete dominance.
—  You may see an example of this in the lab
today!
Genetics with a Smile
—  Today
we will be creating smiley babies to
show how traits are selected and passed
from parents to offspring!
Genetics with a Smile
Part A. Smiley Face Traits
—  Obtain 2 coins from your teacher. Mark one coin
with “F” and the other coin with “M” to
represent each of the parents (male and female).
The parents are heterozygous for all of the Smiley
Face traits.
—  Flip the coins for parent for each trait. If the coin
lands with heads up, it represents a dominant
allele. A coin that lands tails up indicates a
recessive allele. Record the result for each parent
by circling the correct letter. Use the results and
the Smiley Face Traits page to determine the
genotype and phenotype for each trait.
Genetics with a Smile Example
Trait Female Face shape C c Male Genotype Homozygous or Heterozygous
? C c Dominant Phenotype or Recessive? Genetics with a Smile
Part B. Is it a boy or girl?
—  To determine the sex of your smiley face, flip the coin for the
male parent. Heads would represent X, while tails would be
Y. Female have 2 X chromosomes, and thus they will always
pass on an X chromosome.
Part C. Create Your Smiley Face!
—  Use the Smiley Face Traits chart and your results from Part A
to create a sketch of your smiley face on a separate sheet of
paper.
—  Three things to remember…
◦  Sketch your smiley face in pencil before adding colors
◦  Include a name for your smiley face
◦  Include your name on the front of the sheet so that we can see
that you made it.
Genetics with a Smile
Work Agenda
q  Part A—Work
with your partner to
determine the genotype and phenotype of
each trait for your baby
q  Part B—Determine the sex of your baby
q  Part C—Use your data and the chart to
create your smiley face
◦  Use PENCIL first, THEN add colors
Objective check!
Did we…
q Distinguish between genotype and
phenotype?
q Demonstrate that traits are passed from
parents to offspring in random
assortment?
Exit Slip
—  Why
did we use a coin flip to determine
which allele the baby would get from each
parent?
—  How does this fit our picture of sexual
reproduction?