Teacher:
Subject/Class:
8th Grade Science
Objective(s): What will students know/be able to do at the end of class?
Date/Period:
11/22/2010
When/how will I post, state, reinforce, and review the objective(s) during the lesson?
Are my objectives aligned with state standards and have I tagged each objective accordingly?

SWBAT use the genotypes of offspring to determine the genotypes and phenotypes of parents and create
pedigrees with this information.
Assessment(s): How will I measure my each student’s mastery of the objective(s)?
Are my assessments aligned with the day’s objective(s)?
Formative Assessments
 Homework Assignment
Key Ideas: What 3-5 key ideas or steps will I emphasize?



Each offspring gets ½ of their chromosomes
from each parent.
If the dominant allele is present, the
dominant trait will be expressed, even if the
other allele is not the same.
The recessive allele will only be expressed if
BOTH alleles are recessive.
Link to Summative Assessments
 Weekly quiz, Unit Quiz, NY State Intermediate
Science Exam
Potential Misunderstandings: What might students
misunderstand or struggle with?


Thinking that an individual with a dominant trait has
to be homozygous.
Not tracing traits back through generations, only
looking at parents.
genda
Time
Mins
7
20
Description of Instruction
Opening
Review: What will students do upon entering class? Is it quick & do-able?
Do Now: Reading Pedigrees Review
Preview: How will I preview objective(s), agenda, and assessment?
Scholar read aim. Teacher review agenda, exit ticket to be given at end of
class.
Hook: How will I capture the class’s interest/ motivate them to learn?
We have spent several days creating Punnett Squares using the parents’
genotypes to predict the genotypes and phenotypes of the offspring.
Today, we’re going to look at it a little bit backwards- we’re going to use
the genotypes of the offspring to figure out what the possible genotypes
and phenotypes of the parents are. We are going to do this using
pedigrees.
Intro to New Material (“I/We”)
Description
Today, I’m going to have you explore pedigrees on your own and see if you
can figure out how to determine the genotype of the parents using the
phenotypes of the offspring. Read the paragraph that describes the family,
begin by drawing the symbols for each member of the family and then
write the genotypes and show the phenotypes for each person.
(Have two pairs show their pedigrees and explain how they got them.
Then, go over what they should have gotten and why.)
Now, let’s go through this mouse fur example together.
The first thing we have to do is figure out which trait is dominant.
Which one do you think is dominant and why? (Black- there are more
mice with that fur color.)
Materials
Do Now (part of
packet)
Packet
OK. So, if black fur is dominant, what letter are we going to use for their
genotypes? (B for black)
So, in order for a mouse to have white fur, what does that mouse’s
genotype HAVE to be? (bb)
Great- write the genotype of all the white mice in the pedigree under their
symbol. You have 15 seconds.
Now, we have to figure out how to determine the genotype of the black
mice on the pedigree. How you do think we’re going to do that? What do
we know about the parent of a white mouse? (has to have a little b allele)
Fill out the pedigree with what you think the genotype of the black mice
are. We’re going to see if you’re correct in a couple of minutes.
15
3
(Once scholars have completed their genotypes. Go through pedigree and
see if they were able to accurately determine the genotypes of the black
mice. Remind them to use B- if they cannot determine whether the mouse
is homozygous or heterozygous.)
Differentiation
Teacher circulating to help struggling scholars.
Independent Practice (“You”)
Description
Now, that you’ve seen how to use genotypes of offspring and pedigrees to
figure out the genotypes of parents, take a look at the pedigree chart for
eye color on the next page. See if you can apply what you’ve learned about
genotypes and phenotypes to figure out the genotypes of all of the
individuals on the pedigree. You may work in pairs using whisper voices.
If you thought that pedigree was easy, I’m ready for you to tackle a
challenge. The next problem combines eye color and handedness. Working
in your pairs, see if you can determine whether or not each statement is
true or false.
Differentiation
The teacher is circulating to assist scholars that are having difficulties.
Closing: How will I revisit objective(s) & ensure understanding?
Description
Go over the independent practice- answer questions about genotypes and
phenotypes. Assign homework- additional practice with pedigrees.
Packet
Packet
_____________________________________________
________________________________________
Aim: SWBAT use a pedigree to determine the genotypes and phenotypes of parents from the genotypes
and phenotypes of their offspring.
Do Now:
Create Your Own:
Using the back of this sheet, draw the pedigree described in the paragraph below:
Brown eyes are a dominant eye-color allele and blue eyes are recessive. A brown-eyed woman whose father
had blue eyes and whose mother had brown eyes marries a brown-eyed man whose parents are also browneyed. They have a son who is blue-eyed. Please draw a pedigree showing all four grandparents, the two
parents, and the son.
Once you have drawn the symbols for each of the family members, go back and determine what the genotype
and phenotypes of each of the individuals are. You can use the back of this page for your pedigree.
Mouse Fur:
Independent practice:
Examine the following pedigree chart of eye-color inheritance, and answer these questions about it. Consider the most
probable combination of genes in each individual. (Blue eyes are shown by the shaded symbols.)
What are the genotypes of:
1._____
2._____
3._____
8._____
9._____
Master Challenge:
Assume that in man, right-handedness (R) is dominant over left-handedness (r), and that brown eyes (B) are dominant
over blue eyes (b).
As shown below, a right-handed, blue eyed man married a right-handed, brown-eyed woman. They had two children one
of which was left-handed and brown-eyed and the other right-handed and blue-eyed. By a later marriage with another
woman, this man had nine children, six of whom were right-handed and brown-eyed and three of whom were left-handed
and brown-eyed.
Answer the following with true (T) or false (F):
a. The husband was heterozygous for eye color
b. His first wife was heterozygous for right handedness
c. The second wife was presumably homozygous for brown eyes
d. The left-handed child of the first wife was homozygous for left handedness.
e. All of the children of the second marriage were homozygous for eye color.
f. The most probable genotype for the right-handed child of the first marriage is a heterozygous combination of genes.
g. The husband and both wives were homozygous for the righthanded condition.
h. The three left-handed children of the second wife were heterozygous for this condition.
(Hint! You probably want to draw this pedigree using the symbols you are used to using. Might want to
draw 2 pedigrees!!!)
_____________________________________________________
_______________________________________________________
Homework- Pedigree Practice
I
II
1
2
1
2
4
5
3
= Huntington’s
Disease
6
7
8
III
1
2
3
4
5
1. Which members of the family above are afflicted with Huntington’s Disease? _________________________________
2. There are no carriers for Huntington’s Disease- you either have it or you don’t.
With this in mind, is Huntington’s disease caused by a dominant or recessive trait? ____________________________
3. How many children did individuals I-1 and I-2 have? _______________________________________________
4. How many girls did II-1 and II-2 have? ______________ How many have Huntington’s Disease? ________________
5. How are individuals III-2 and II-4 related? ________________________ I-2 and III-5? _________________________
6. The pedigree to the right shows a family’s pedigree
for Hitchhiker’s Thumb. Is this trait
dominant or recessive? _______________________
I
7. How do you know? _________________________
___________________________________________
1
2
1
2
II
8. How are individuals III-1
and III-2 related? ________________________
9. How would you name the 2 individuals that
have hitchhiker’s thumb? ___________________
III
3
1
2
IV
10. Name the 2 individuals that were
carriers of hitchhiker’s thumb. ______________
11. Is it possible for individual IV-2 to be a carrier? ___________ Why?
________________________________________
1
2
3
4
3
4
12. The pedigree to the right shows a family’s pedigree
for colorblindness. Which sex can be carriers of
colorblindness and not have it? ______________________
**half-shaded = carrier of disease
I
13. With this in mind, what kind of trait is
II
colorblindness (use your notes)? ______________________
14. Why does individual IV-7 have colorblindness?
_________________________________________________
III
15. Why do all the daughters in generation II carry the
colorblind gene? ____________________________________
16. Name 2 IV generation colorblind males. _________
IV
1
2
3
4
5
6
7
8