Download Pedigrees and Sex-linked Traits

Warm-Up #7
2/29/12
Define the following in your own words:
1) Incomplete Dominance
2) Codominance
3)Independent Assortment
4) What two factors affect your
characteristics?
5)What are the offspring possibilities if
Dad has IAIA blood and Mom has IAIB
blood?
Dihybrid Cross of WwDd x WwDd
WD
WD
Wd
wD
wd
Wd
wD
wd
Quiz Today!
You have 5 to 10 minutes to look over the
highlighted portions of the notes
After the quiz, turn it in up front and grab
today’s notes
Write down the essential questions
Warm-Up # 8
3/1/12
1) Mike has IAi blood and his wife has ii
blood, what type of blood can there
offspring have?
2) Cindy has IAIB blood and her husband
has IAIB blood, what type of blood can
their children have?
3) Kerri has IBi Blood, what is his
phenotype?
4) Jim has A blood, what can his genotype
be?
Pedigrees and Sexlinked Traits
Chapters 14-1 and 14-2
Mendelian Genetics
Unit 8
What Are We Learning?
Essential Question:
 What is the
purpose of a
pedigree?
Objectives:





Identify the types of human
chromosomes in a karyotype
Explain how sex is
determined
Explain how pedigrees are
used to study human traits
Describe examples of the
inheritance of human traits
Explain how small changes in
DNA cause genetic disorders
Human Traits
Human traits are inherited according to the
same principles Mendel discovered with
the garden peas.
Biologist must identify an inherited trait
controlled by a SINGLE gene.
They study how the trait is passed from
one generation to the next.
Common Inherited Traits
Pedigree
Chart that shows how traits
controlled by one gene are
inherited in a family tree.
Pedigree Rules and Symbols
Males =
Females =
A marriage line =
Children (first to last) =
(connected to parents with vertical line)
Symbols and Shapes
A shaded square or circle indicates the
person expresses the trait.
A square or circle not shaded indicates the
person does not express the trait.
A square or circle half shaded indicates the
person is a carrier for the trait.
This pedigree shows the inheritance of attached ear lobes.
1. Which parent has attached ear lobes?
2. How many children do the parents have?
3. Which child has attached ear lobes?
4. Which child is married?
5. Does this child’s spouse have attached ear lobes?
6. Do any of this child’s children have attached ear lobes?
Answers
1.
2.
3.
4.
5.
6.
Father
Three
Oldest Daughter (II-1)
Youngest Son (II-3)
No
Yes (III-2)
Hint Hint...Wink Wink
If the majority are
filled in the trait is
Dominant (AA/Aa)
If not many are filled
in it is recessive (aa).
Sex Chromosomes
Every egg has one X sex chromosome.
Half of all sperm have an X sex
chromosome and half have a Y sex
chromosome.
Females XX
Males XY
Sex Chromosomes
Gene located on a sex chromosome are
called sex-linked
Most of these sex-linked genes are on
the X chromosome
Males only get a “single-dose” (only have
one X)
What is on the X is what shows!
Females get two “doses” of the gene
They follow rules of dominance
R = red eyes
r = white eyes
Pure Red eyed Female X
White eyed Male
Genotype 2:2
Phenotype 2:2
Sex-linked Disorders
More Common in Males
Males only receive 1 X-chromosome!!! Xchromosome carries the gene.
 Examples: Hemophilia, Muscular dystrophy,
Color blindness: 1 in 10 males are color blind
Practice!
On a separate sheet of paper, build a pedigree
for any disease.
Your pedigree must include three generations.



The 1st generation are the Grandparents
They have 5 kids (you pick ratio) =2nd Generation
They have 10 Grandkids, you pick who gets married
and how many kids they have.
You must include carriers and those infected by
coloring them.
Name the people in your pedigree and make a
key!
Give your pedigree a title
Three Generation Pedigree for
Heart Disease
KEY