romanovs and revolution

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Romanovs and Revolution A Genetic History Mystery

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Romanovs and Revolution. A Genetic History Mystery. The Romanovs. Tsar Nicholas II. Alexandra. Olga. Tatiana. Alexei. Marie. Anastasia. The Romanov children. Tsarevich Alexei. Grigory Rasputin. Hemophilia. Caused by a single, recessive allele. - PowerPoint PPT Presentation

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Page 1: Romanovs and Revolution

Romanovs and Revolution

A Genetic History Mystery

Page 2: Romanovs and Revolution

Tsar Nicholas IIAlexandra Olga

Tatiana

Marie Anastasia

Alexei

The Romanovs

Page 3: Romanovs and Revolution

The Romanov children

Tsarevich Alexei

Page 4: Romanovs and Revolution

Grigory Rasputin

Page 5: Romanovs and Revolution
Page 6: Romanovs and Revolution

Hemophilia•Caused by a single, recessive allele.•This allele codes for a blood-clotting protein. If the protein is defective, then the blood does not clot properly. •Untreated, victims often die in childhood or teen years, rarely live to adulthood.

Page 7: Romanovs and Revolution

The Windsor Pedigree

This pedigree shows who had hemophilia in the Windsor family line. Why only males? And who are the carriers?

Page 8: Romanovs and Revolution

The Completed Pedigree

Notice only women can be carriers. Why?And here’s the real mystery:

Why are there no carriers before Victoria?

Page 9: Romanovs and Revolution

Sex-linkage• Sex-linked traits are carried on the

sex chromosomes (X or Y). Women have two X chromosomes, while men have an X and a Y.

• Most sex-linked traits that have been studied well are X-linked. Women need two copies of a recessive X-linked trait to show the trait. Men only need one.

Page 10: Romanovs and Revolution

How X-linkage works• Only women can

be carriers of X-linked traits, since they have two X chromosomes.

• Men can pass an X or a Y to their children. Women only have an X.

Page 11: Romanovs and Revolution

Red-Green Color Blindness - X-linked

• If your vision is normal, these should read: A = 29, B = 45, C = abstract, D = 26.

• If you are red-green color blind, they might read: A = 70, B = nothing, C = 5, D = nothing.

Page 12: Romanovs and Revolution

Color-blindness Inheritance

If I have a brother who is red-green color blind (which I do), where did he get the color-blind gene from? Mom or Dad?

What are the odds that I am a carrier?

Page 13: Romanovs and Revolution

Things to Remember

• When doing Punnett squares for X-linked traits, we track not just the alleles, but the chromosomes they are carried on.

• This is only for traits on the sex chromosomes, not for traits on the other(somatic) chromosomes.