Download Pedigree charts

1. What do the circles represent?
2. What do the squares represent?
3. Why are some shapes dark and others light?
4. What does a line mean between two shapes?
In humans, dark hair (B) is dominant to blond hair.
Dark haired individuals are shaded dark.
Clear shapes are blonde.
1. How many of the children have dark hair?
2. What are the genotypes of the parents?
3. What is the genotype of the sons?
4. What are the two possible genotypes of the daughters?
Vocabulary: Autosomal and XLinked (aka sex-linked)
Autosomal traits on found on any
chromosome EXCEPT the X or Y
chromosome.
X-Linked traits are found on the X
chromosome.
Because males only have 1 X chromosome, any
trait found on their X WILL BE EXPRESSED
Females have 2 X chromosomes, so a recessive
trait will only be expressed if the female has a
recessive on BOTH of her X chromosomes.
1. The pedigree to the right
shows the passing on of
colorblindness. What sex
can ONLY be carriers of
colorblindness?
2. With this in mind, what kind
of non-mendelian trait is
colorblindness?
3. Why does individual IV-7
have colorblindness?
4. Why do all the daughters in
generation II carry the
colorblind gene?
5. Name 2 IV-generation
colorblind males.
I
II
III
IV
1
2
3
4
5
6
7
8
1. What do the letters stand for?
2. Is the trait represented dominant or recessive? How do you know?
3. Is the trait represented autosomal or x-linked? How do you know?
1. Is the trait represented dominant or recessive?
2. Is it autosomal or x-linked
I
1
2
3
4
II
III
1. Is the trait represented dominant or recessive?
2. What is the genotype of P I, # 3 and 4?
3. Is the trait autosomal or x-linked