Transcript Pedigree Chart

Pedigree Chart
A diagram that shows family
connections between several
generations
What do the symbols mean?
= male
I
= female
II
= carrier
= affected individual
= mating
Offspring in birth order;
I and II refer to generations
Identical Twins
Fraternal Twins
What is this called?
Autosomal, X-linked, Y-linked?
Dominant or recessive?
Expressed in both sexes
in similar frequencies = autosomal
Expressed in many generations,
only takes one allele to express it
= dominant
?
?
Critical thinking - solve the puzzle
How is this trait passed on?
Colorblindness
2
1
3
8
4
9
Hairy Ears
6
5
10
11
7
12
13
Mode of inheritance? Autosomal/X-Linked?
(How do you know?)
Is it dominant or recessive?
(How do you know?)
Tell the condition of each person:
Normal color vision,
Carrier (which means that person has normal
color vision, but they can pass it on to their
children through their X-sex chromosome)
Colored Blind
http://colorvisiontesting.com/
How does the world look to a color blind person?
Mode of inheritance? Autosomal/X,Y-Linked?
(How do you know?)
Is it dominant or recessive?
(How do you know?)
Deafness in Dalmations
Is this trait sex-linked or autosomal?
(How do you know?)
Is it dominant or recessive?
(How do you know?)
Where is inbreeding occurring?
What impact does inbreeding have on
the passing of such a trait?
(Hint: look at the offspring)
Baldness
Male-Pattern Baldness
1. What is the mode of inheritance for this trait?
X-linked, y-linked, or autosomal? (Tell how you know.)
2. Is it dominant or recessive? (Tell how you know.)
3. How can females get Alopecia?
Tell what has to happen regarding the gene.
NEW YORK (Reuters Health) - Researchers in Germany have
found that variations in a gene related to male sex hormones
may be at the root of male-pattern baldness, the most common
form of hair loss. The culprit is the androgen receptor gene,
and it dwells on the X chromosome, which all men inherit from their
mothers. So look at your mom’s dad (your maternal grandfather)
as a predictor of baldness, not our own father.
Female-Pattern Alopecia
The Story of Hemophilia
Late in the summer of 1818, a human sperm and egg united to form a human zygote.
One of those gametes, we don't know which, was carrying a newly mutated gene.
a single point mutation in a nucleotide sequence coding for a particular amino acid
in a protein essential for blood clotting. The zygote became Queen Victoria of England
and the new mutation was for hemophilia, bleeder's disease, carried on the X
chromosome.
A century later, after passing through three generations, that mutation may have
contributed to the overthrow of the Tsar and the emergence of communism in Russia.
Victoria passed the gene on to some of her children and grandchildren, including
Princess Alexandra, who married Nicholas II, Tsar of Russia, in 1894. By 1903, the
couple had produced four daughters. The next year, the long awaited male heir
appeared - His Imperial Highness Alexis Nicolaievich, Sovereign Heir Tsarevich,
Grand Duke of Russia. From his father, the baby Alexis inherited the undisputed claim
to the throne of all the Russias. From his mother, he inherited an X chromosome
carrying a copy of the mutant gene for hemophilia. Soon after his birth, signs of
Alexis' mutant gene appeared. At six weeks, he experienced a bout of uncontrolled
bleeding and by early 1905 the royal physicians had concluded that he was suffering from
hemophilia.
Questions:
1. What is hemophilia?
2. What chromosome is this genetic disease carried on?
3. Who contracted the disease? (Tell how you know.)
4. Why did they contract it and not others of same gender,…or the other gender?
5. What was the average lifespan of those who died from it? Why do you think that is?
Contrary to popular belief, inbreeding does not result in "monstrous" offspring. Marrying close relatives,
as often occurred in royal families did increase the chances that recessive harmful alleles (like hemophilia)
would be inherited. Inbreeding has caused many breeds of dogs to have harmful genetic traits.
Dalmations are often deaf, and other dog breeds have high frequencies of epilepsy, blindness, and
hip dysplasia. It is true, that mutts are often hardier and have less health problems.
Determine the model of inheritance
autosomal dominant
Pedigree #1
autosomal recessive
Pedigree #2
Sex-linked recessive
Pedigree #3
- Related to each other
Pedigrees of two US families with high incidence of mesothelioma