How traits are passed down
Warm Up 3/20/12
Read the scenario below and create a punnet square
based on the information given.
Andy and Amy just got married. Andy has brown hair
with a genotype of Bb. Amy is a blond with the
genotype of bb.
1. Tell me where the female and male alleles would be
placed on the punnet square.
2. Create a punnet square that would show the possible
outcomes of their offspring.
3. What percentage of their children would have blond
hair? How do you know?
Announcements
 Extra credit projects are due on Monday of next week
(3/26).
 I will not be able to stay after on Thursday and Friday
of this week!
 If you need make up work see me in the morning!
Think and write: 10
Read the questions below and pick one to answer. Be
sure to stop and think before you answer it. Be sure to
use proper grammar and punctuation.
Do you resemble (look like) anyone in your family?
How do you know.
2. Are their in diseases in your family that are common?
How do you know? How has that influenced your
behavior?
1.
Pedigrees
-Scientists use pedigrees to track genes over generations.
-Pedigrees are family trees which show which individuals
in the family get certain diseases.
VII. Pedigree
Male
Parents
Female
Siblings
Affected
male
Affected
female
Mating
Known
heterozygotes
for recessive
allele
Death
Pedigrees
illustrate
inheritance
How to read a pedigree
 Horizontal lines connecting a male and female
represent mating.
 Vertical lines pointing down from a couple represent
their children.
 Subsequent generations (or the next generation) are
written underneath the parents and the oldest
individuals are found at the top of the pedigree.
Why do we need pedigrees?
 If the purpose of a pedigree is to analyze the pattern of
inheritance of a particular trait, it is common to shade
in the symbol of all individuals that possess this trait.
 In the pedigree below, the grandparents had two
children, a son and a daughter. The son had the trait in
question. One of his four children also had the trait.
 For example:
VII. Pedigrees
Pedigrees illustrate inheritance

A half-shaded
circle or square
represents a
carrier, a
heterozygous
individual.
VII. Pedigrees
Pedigrees illustrate inheritance

I
1
2
II
2
1
III
?
IV
1
2
1
3
4
4
3
2
5
3
4
5
A horizontal line
connecting a circle
and a square
indicates that the
individuals are
parents, and a
vertical line
connects parents
with their offspring.
VII. Pedigrees
Pedigrees illustrate inheritance

I
1
2
II
2
1
III
?
IV
1
2
1
3
4
4
3
2
5
3
4
5
A horizontal line
connecting a circle
and a square
indicates that the
individuals are
parents, and a
vertical line
connects parents
with their offspring.
Generations
 Each row on a pedigree indicates a different
generation.
 For example, children of parents represent a
generation. Lets call them F1
 When those children have children they create a new
generation. We would call them F2.
Guided Practice
 We are going to practice analyzing pedigrees using the
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skills we JUST learned.
If you forget something, its ok. Look back at your notes
to answer the questions.
You will be given a pedigree practice sheet
Do Not write on it. Class set.
Answer the questions quietly in your notebook.
15 minutes.
Review
 Take two minutes to discuss your answers with a
partner.
Discuss:
1. Which questions did you find most difficult?
2. Why were they hard?
3. What information could I have given you to make it
easier?
Independent Practice
 You will complete questions 12-22 on your own.
 This will serve as your exit ticket.
Warm Up 3/21/12
Fill in the blanks below:
1. Scientists use______________ to track genes over
generations.
2. Pedigrees are ________________which show which
individuals in the family get_________________.
3. What type of information do you get from a
pedigree.
Announcements
 Extra credit projects are due on Monday of next week
(3/26).
 I will not be able to stay after on Thursday and Friday
of this week!
 If you need make up work see me in the morning!
Patterns of Inheritance
 Autosomal dominant
 Autosomal recessive
 X-linked recessive
What does this mean?
Autosomal Dominant
 If a disease is autosomal dominant, it means you only
need to get the abnormal gene from one parent in
order for you to inherit the disease.
 In many cases, one of the parents have the disease.
 Dominant inheritance means an abnormal gene from
one parent is capable of causing disease, even though
the matching gene from the other parent is normal.
The abnormal gene "dominates" the pair of genes. If
just one parent has a dominant gene defect, each child
has a 50% chance of inheriting the disorder.
 Example: Huntington’s Disease
For example
 For example, if four children are born to a couple and
one parent has an abnormal gene for a dominant
disease, statistically two children will inherit the
abnormal gene and two children will not.
 Children who do not inherit the abnormal gene will
not develop or pass on the disease.
Autosomal recessive
 An autosomal recessive disorder means two copies of
an abnormal gene must be present in order for the
disease or trait to develop.
 If you are born to parents who both carry an autosomal
recessive change (mutation), you have a 1 in 4 chance
of getting the malfunctioning genes from both parents
and developing the disease. You have a 50% (1 in 2)
chance of inheriting one abnormal gene. This would
make you a carrier.
 Example: Sickle Cell Anemia
Example of recessive:
 Ms. Adeeyo’s dad is African and carries the gene for
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sickle cell.
Ms. Adeeyo’s mom is from the USA and does not.
Thus, I have a ¼ chance of inheriting the gene from 1
parent. As a result, my parents had a 25% chance of
having a child with sickle cell.
My parents had a 50% chance of having children that
are carriers of the mutation.
Both my sister and I are carriers of the mutation. So, if
my parents had more kids, they would be more likely
to either have the disease or not carry the gene at all.
X-linked recessive
 Inheritance of a specific disease, condition, or trait
depends on the type of chromosome affected
(autosomal or sex chromosome).
 It also depends on whether the trait is dominant or
recessive. Sex-linked diseases are inherited through
one of the sex chromosomes (the X or Y chromosome).
 Example:Hemophilia and Muscular Dystrophy
Quick check for understanding
Which of the following is an example of an
autosomal dominant disease?
A) Huntingtons?
B) Sickle Cell
C) Hemophilia
1.
Quick check part 2
2. Explain in your own words why Sickle Cell would be
considered a recessive disease?
Pedigree Simulation: Directions
 You are going to use this as a way to “experience” how diseases
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like Sickle Cell, Hemophilia and Huntington’s are passed down.
You will receive a worksheet to record your genotypes on.
You (Students) will partner up and pick allele cards to determine
their genotypes and if you have a disease.
Then, you will randomly contribute one card each to simulate
offspring production and record the genotypes of their offspring
with the allele cards.
This will be done three times.
Lastly, you will choose one disease and form a pedigree from this
information using correct symbols for gender, and who's
affected.
Exit ticket
If you are born to parents who both carry an
autosomal recessive change (mutation), you have a
_________ chance of getting the malfunctioning
genes from both parents and developing the disease.
2. Hemophilia is an example of an _______________
disease.
3. If a disease is autosomal dominant, it means you only
need to get the abnormal gene from
________________in order for you to inherit the
disease.
1.
Warm Up 3/21/12
What does a pedigree chart show?
2. Based on your knowledge from punnet squares, write
a paragraph discussing the role of probability in the
passing of genetic traits to offspring.
1.
Announcements
 Test on Friday!
Mini-Project
 Today’s mini-project will be creating your own Family
Pedigree Chart.
 You will use the rubric seen below.
 You will also be earning class participation points for
this activity.
Outline and Roughdrafts
Take 30 minutes to jot down your thought process.
This should guide your thinking on how to make your
final draft.
Final draft
Warm Up 3/22/12
 What did you learn from your family pedigree?
 Are their traits being passed on that you were unaware
of?
Announcemnts
 Study guide for the test is posted on my website.
 Extra credit due soon.
 Get ready for the test tomorrow
Stations: when pedigrees go wrong
 Different stations around the room have various
articles about pedigrees and diseases.
Stations
Disease
Station 1
Station 2
Station 3
Station 4
Station 5
Which pattern of How it affects a
heredity is this? person?
What happens
to your body’s
ability to
maintain
homeostasis?
Argue your point
 After reading the article about puppy mills, the russian
royal family and other types of inbreeding how do you
feel?
 Do you think that it is right to selectively breed dogs in
this way?
 Respond to this question by making a claim,
supporting it with evidence and using supporting
details from the argument?
 The first draft will serve as a rough draft while the final
draft will be your exit slip!
Warm Up 3/13/12
If you are born to parents who both carry an
autosomal recessive change (mutation), you have a
_________ chance of getting the malfunctioning
genes from both parents and developing the disease.
2. Hemophilia is an example of an _______________
disease.
3. If a disease is autosomal dominant, it means you only
need to get the abnormal gene from
________________in order for you to inherit the
disease.
1.
Announcements
 Test today!
 Please place all make up work in the bin!
10 minute review
 Time to ask me any questions before we begin.
Testing!
 Please begin your test.
 Good luck 