FRUIT FLY GENETICS
DO NOW TUESDAY
• Let’s see what you remember. Give the genetics term
that describes each of the following:
a) AA
b) Aa
c) Aa
d) Red flowers
e) A
f) a
DO NOW TUESDAY
• Complete the following
a) If black fur is dominant (B) and white fur is recessive
(b), write the genotype for a heterozygous rabbit.
b) Write the genotype for a white rabbit.
c) Cross the rabbits from parts a and b using a Punnett
square.
d) Give the expected genotypic and phenotypic
percentages and ratio n the offspring.
• TODAY’S PLAN
•
•
•
To explain what is meant by phenotype/genotype.
To define heterozygous, homozygous, dominant, and
recessive.
To explain the results of a genetic cross (Punnett
Square).
• TODAY’S DO
•
•
•
We will finish the class survey from yesterday.
We will practice a few Punnett Squares.
We will begin the Alien Genetics Activity.
Class Survey (Pages 86-87)
DATA TABLE
Total Number ______________
Trait 1
Number of students
Trait 2
A
Free ear lobes
Attached earlobes
B
Hair on
fingers
No hair on fingers
C
Widow’s peak
No widow’s peak
D
Curly hair
Straight hair
E
Cleft chin
No cleft chin
F
Smile dimples
No smile dimples
Your # from the circle on page 87:
Number of Students
DO NOW MONDAY
• Cross the following parents and give the genotypic and
phenotypic results.
• Sepia eyes in fruit flies are recessive (e), while red eyes
(E) are dominant. Cross a homozygous red-eyed fly with
a homozygous sepia-eyed fly.
E
e
• TODAY’S PLAN
•
To explain the results of a genetic cross (Punnett
Square).
• TODAY’S DO
•
We will complete the Alien Genetics Activity.
DO NOW TUESDAY
• Give some reasons why fruit flies are ideal
organisms to use to study genetics.
• TODAY’S PLAN
•
Explain the results of a genetic cross (Punnett
Square).
• Explain why fruit flies are ideal for studying
genetics.
• Identify specific genetic traits of fruit flies.
• TODAY’S DO
•
We will begin a Web Quest to help you learn
more about genetics and fruit flies.
March Madness Fruit Fly Style
• 1st Round
• Move the recessive trait on to the next round
• 2nd Round
• Move the trait found on the lower numbered chromosome on to
the next round
• Semifinal Round (Round 3)
• Move the trait that is NOT sex-linked on to the next round
• Final Round (4th Round)
• The trait with the longer gene is the winner!
• Best resource to use is
• http://flybase.org
• In the quick search box, click on the Data Class tab. Set the parameters to
Species (Dmel only), Search (ID/Symbol/Name), Data Class (genes). The
first name of the specific trait being searched should be placed in the Enter
Text box, then click Search.
• There will be a highlighted blue bar at the middle/bottom of the screen that
shows the length of the gene.
DO NOW THURSDAY
• Describe the P generation, F1 generation, and F2
generations from Mendel’s experiments.
P generation
• Parents- pure breeding- homozygous dominant (RR) with
dominant phenotype and homozygous recessive (rr) with
recessive phenotype
RR x
rr
F1 generation
• Offspring- hybrids- heterozygous (Aa)- all dominant
phenotypes and NO recessive phenotypes

F2 generation
• Offspring of F1- 3:1 phenotypic ratio- 3 dominant
phenotypes to 1 recessive phenotype- corresponds to a
cross between 2 heterozygous individuals.
dominant
dominant
dominant
recessive
• TODAY’S PLAN
•
•
•
To explain the results of a genetic cross (Punnett
Square).
To identify specific genetic traits of fruit flies.
To use a specific trait of fruit flies to study inheritance.
• TODAY’S DO
•
•
•
We will discuss specific traits of fruit flies, including
how to distinguish males and females.
We will observe and record data for our P and F1
generations.
We will prepare the cross of our F1 generation to
produce our F2 generation.
“Sexing” Fruit Flies
• “Sexing” means to distinguish between male and female
fruit flies.
• Turn the fly so that it is laying on its back. A female will
have a light colored end. A male will have a dark colored
end.
• Also, females are generally larger than males.
Wild type “Normal” Fruit Flies
• Red eyes
• Long wings
• Bristles on back
• Light colored body
Mutations in Fruit Flies
• White eyes
• Sepia Eyes
Mutations in Fruit Flies
• Apterous (wingless)
wings
• Vestigial wings
• Miniature wings
Mutations in Fruit Flies
• Ebony body
• Stubble bristles
DO NOW FRIDAY
• Is your fruit fly mutation dominant or recessive?
Explain how you know.
• Hint: Consider what you saw in the F1 flies
yesterday.
• TODAY’S PLAN
•
To explain the results of a genetic cross (Punnett
Square).
• TODAY’S DO
•
We will complete a Genetics Gizmo on the
Chromebooks.
•
•
Username: 2016bcmsscience
Password: bcmsscience
•
Find Gizmo: Mouse Genetics (One Trait)
(Maggots)
(Maggots)
Predictions
• If your apterous mutation is inherited as a recessive (a)
trait, let’s make some predictions about what we should
see in the F2 generation.
F2 Expected Genotypic Ratio:
F2 Expected Phenotypic Ratio: