Sex-Linked Inheritance Tutorial

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Press the F5 button on your keyboard to start the tutorial.:

Press the F5 button on your keyboard to start the tutorial.

Sex-Linked Inheritance:

Sex-Linked Inheritance Place your keyboard aside. You will navigate with the mouse. Start from beginning The Guzman Family The Jackson Family The Chang Family Chromosomes & Karyotypes Sex-linked Inheritance

Gregor Mendel:

Mendel discovered the basic patterns of heredity in the 1800s when he was breeding pea plants. BACK HOME Gregor Mendel

Gregor Mendel:

Mendel discovered the basic patterns of heredity in the 1800s when he was breeding pea plants. Remember that purple flowers were dominant to white flowers. BACK HOME Gregor Mendel DOMINANT recessive

Gregor Mendel:

Mendel discovered the basic patterns of heredity in the 1800s when he was breeding pea plants. Remember that purple flowers were dominant to white flowers. Cross a heterozygous purple flower with a homozygous recessive white flower. BACK HOME Gregor Mendel P p p p Which genotype goes inside this square? PP pp P p X X P p Which genotype goes inside this square? PP pp P p X X pp Which genotype goes inside this square? PP pp P p X X P p Which genotype goes inside this square? PP P p X X pp pp

Gregor Mendel:

Mendel discovered the basic patterns of heredity in the 1800s when he was breeding pea plants. Remember that purple flowers were dominant to white flowers. Cross a heterozygous purple flower with a homozygous recessive white flower. What is the probability of growing purple flowered plants? BACK HOME Gregor Mendel P p p p P p pp P p pp 0% 25% 50% 75% 100% correct

Gregor Mendel:

Mendel discovered the basic patterns of heredity in the 1800s when he was breeding pea plants. Remember that purple flowers were dominant to white flowers. Cross a heterozygous purple flower with a homozygous recessive white flower. What is the probability of growing homozygous dominant plants? BACK HOME Gregor Mendel P p p p P p pp P p pp 0% 25% 50% 75% 100% correct

Gregor Mendel:

Mendel published his work in 1866. Even though his work is still very useful, it does have some limitations. Since 1866, scientists have been busy! As great as Mendel's work was, can we determine the gender of an individual using Mendel's work? BACK HOME Gregor Mendel Limitations? What limitations? No Yes Correct. My work cannot predict offspring gender. But my work was the foundation for others. X

Chromosomes and Karyotypes:

In humans, there are 23 pairs of chromosomes (46 total). Karyotypes show an individual's chromosomes. T he final pair of chromosomes allows us to determine the sex of the individual. Click on the karyotype above to reveal the sex of the individual used to create this karyotype. BACK HOME Chromosomes and Karyotypes This karyotype shows a girl. Let me teach you how.

Chromosomes and Karyotypes:

S o how do we know which is a female or male karyotype? Find chromosome pair #23. Like any pair of chromosomes, #23 comes in pairs (one from each parent). If the two chromosomes are equal sized, the individual has the XX chromosome combination and would be female . If the two chromosomes of #23 are different sized, the individual has the XY chromosome combination and would be male. Click on the female sex chromosomes in the above karyotype. BACK HOME Chromosomes and Karyotypes

Chromosomes and Karyotypes:

Click on the male karyotype. BACK HOME Chromosomes and Karyotypes correct

Sex Determination:

Knowing that mom has the XX combination and dad has the XY combination, can we determine the probability of this couple having a boy or girl? Use the sex chromosomes (as a genotype) and fill in the Punnett square just like you would perform a genetics problem. BACK HOME Sex Determination X X X Y X X X X X Y X Y

Sex Determination:

BACK HOME Sex Determination X X X Y X X X X X Y X Y What is the probability of the child being born as a boy? 0% 25% 50% 75% 100% correct

Sex-Linked Inheritance:

BACK HOME Sex-Linked Inheritance Some traits and genes are found on the X or Y chromosome. These traits are called sex-linked. This means that not only can we predict whether or not a person will be healthy, but we also can predict whether the individual will be a boy or girl. X chromosome Y chromosome

Sex-Linked Inheritance:

BACK HOME Sex-Linked Inheritance Some traits and genes are found on the X or Y chromosome. These traits are called sex-linked. This means that not only can we predict whether or not a person will be healthy, but we also can predict whether the individual will be a boy or girl. Examples of sex-linked traits are: Hemophilia, Here is a normal vein. Click the vein to continue.

Sex-Linked Inheritance:

BACK HOME Sex-Linked Inheritance Some traits and genes are found on the X or Y chromosome. These traits are called sex-linked. This means that not only can we predict whether or not a person will be healthy, but we also can predict whether the individual will be a boy or girl. Examples of sex-linked traits are: Hemophilia, When cut, bleeding can occur. Click the vein to continue.

Sex-Linked Inheritance:

BACK HOME Sex-Linked Inheritance Some traits and genes are found on the X or Y chromosome. These traits are called sex-linked. This means that not only can we predict whether or not a person will be healthy, but we also can predict whether the individual will be a boy or girl. Examples of sex-linked traits are: Hemophilia, A blood clot forms to stop the bleeding. Click the vein to continue.

Sex-Linked Inheritance:

BACK HOME Sex-Linked Inheritance Some traits and genes are found on the X or Y chromosome. These traits are called sex-linked. This means that not only can we predict whether or not a person will be healthy, but we also can predict whether the individual will be a boy or girl. Examples of sex-linked traits are: Hemophilia, In hemophilia however, the clot is very weak and doesn’t stop the bleeding. This disease is caused by a recessive gene on the X chromosome. Click the vein to continue.

Sex-Linked Inheritance:

BACK HOME Sex-Linked Inheritance Some traits and genes are found on the X or Y chromosome. These traits are called sex-linked. This means that not only can we predict whether or not a person will be healthy, but we also can predict whether the individual will be a boy or girl. Examples of sex-linked traits are: Hemophilia, colorblindness , Here is a rainbow flag as seen by most people with normal vision. Click the flag to continue.

Sex-Linked Inheritance:

BACK HOME Sex-Linked Inheritance Some traits and genes are found on the X or Y chromosome. These traits are called sex-linked. This means that not only can we predict whether or not a person will be healthy, but we also can predict whether the individual will be a boy or girl. Examples of sex-linked traits are: Hemophilia, colorblindness , Here is the same flag as seen by many people who are color blind. Click the flag to continue.

Sex-Linked Inheritance:

BACK HOME Sex-Linked Inheritance Some traits and genes are found on the X or Y chromosome. These traits are called sex-linked. This means that not only can we predict whether or not a person will be healthy, but we also can predict whether the individual will be a boy or girl. Examples of sex-linked traits are: Hemophilia, colorblindness , and muscular dystrophy . Over time, the muscles begin to weaken and slowly waste away. Click the weaker bicep muscle to continue.

Sex-Linked Inheritance:

BACK HOME Sex-Linked Inheritance Some traits and genes are found on the X or Y chromosome. These traits are called sex-linked. This means that not only can we predict whether or not a person will be healthy, but we also can predict whether the individual will be a boy or girl. Examples of sex-linked traits are: Hemophilia, colorblindness , and muscular dystrophy . As the muscles weaken, often the sufferer becomes wheelchair bound for the rest of their life. Average life span is only about 25 years.

Sex-Linked Punnett Squares:

BACK HOME Sex-Linked Punnett Squares Since the genes that cause these disorders are usually found on the X chromosome, we will use the letters X H to abbreviate a dominant healthy allele on the X chromosome.

Sex-Linked Punnett Squares:

BACK HOME Sex-Linked Punnett Squares Since the genes that cause these disorders are usually found on the X chromosome, we will use the letters X H to abbreviate a dominant healthy allele on the X chromosome. Key for this tutorial: X H = Dominant healthy

Sex-Linked Punnett Squares:

BACK HOME Sex-Linked Punnett Squares Since the genes that cause these disorders are usually found on the X chromosome, we will use the letters X H to abbreviate a dominant healthy allele on the X chromosome. Therefore X h will be used to abbreviate a recessive unhealthy allele on the X chromosome. Key for this tutorial: X H = Dominant healthy

Sex-Linked Punnett Squares:

BACK HOME Sex-Linked Punnett Squares Since the genes that cause these disorders are usually found on the X chromosome, we will use the letters X H to abbreviate a dominant healthy allele on the X chromosome. Therefore X h will be used to abbreviate a recessive unhealthy allele on the X chromosome. Key for this tutorial: X H = Dominant healthy X h = recessive disease

Sex-Linked Punnett Squares:

BACK HOME Sex-Linked Punnett Squares Since the genes that cause these disorders are usually found on the X chromosome, we will use the letters X H to abbreviate a dominant healthy allele on the X chromosome. Therefore X h will be used to abbreviate a recessive unhealthy allele on the X chromosome. Since most sex-linked disorders are found on the X chromosome, this tutorial will not address Y-linked problems. Key for this tutorial: X H = Dominant healthy X h = recessive disease

Men? Women? Both?:

BACK HOME Men? Women? Both? Men only have two possible chromosome combinations. If guys are healthy, they must be X H Y. Key for this tutorial: X H = Dominant healthy X h = recessive disease

Men? Women? Both?:

BACK HOME Men? Women? Both? Men only have two possible chromosome combinations. If guys are healthy, they must be X H Y. Key for this tutorial: X H = Dominant healthy X h = recessive disease X H Y = healthy

Men? Women? Both?:

BACK HOME Men? Women? Both? Men only have two possible chromosome combinations. If guys are healthy, they must be X H Y. If a guy has a sex-linked disease, he must be X h Y. Key for this tutorial: X H = Dominant healthy X h = recessive disease X H Y = healthy

Men? Women? Both?:

BACK HOME Men? Women? Both? Men only have two possible chromosome combinations. If guys are healthy, they must be X H Y. If a guy has a sex-linked disease, he must be X h Y. Key for this tutorial: X H = Dominant healthy X h = recessive disease X H Y = healthy X h Y = disease

Men? Women? Both?:

BACK HOME Men? Women? Both? Sex-linked disorders are most commonly found on the X chromosome. They are also more common in males because males only have 1 X chromosome. If a male’s only X chromosome is damaged, males do not have a “backup” X chromosome. Key for this tutorial: X H = Dominant healthy X h = recessive disease X H Y = healthy X h Y = disease

Men? Women? Both?:

BACK HOME Men? Women? Both? Sex-linked disorders are most commonly found on the X chromosome. They are also more common in males because males only have 1 X chromosome. If a male’s only X chromosome is damaged, males do not have a “backup” X chromosome. Key for this tutorial: X H = Dominant healthy X h = recessive disease X H Y = healthy X h Y = disease What about my Y chromosome? If my Y chromosome is “healthy” and my X chromosome has a “disease”, will I be healthy? Yes No

Men? Women? Both?:

BACK HOME Men? Women? Both? Key for this tutorial: X H = Dominant healthy X h = recessive disease X H Y = healthy X h Y = disease What about my Y chromosome? If my Y chromosome is “healthy” and my X chromosome has a “disease”, will I be healthy? Actually, no. These disorders are mostly found on the X chromosome. So even though you may have a normal Y chromosome, it won’t protect you from these disorders.

Men? Women? Both?:

BACK HOME Men? Women? Both? But what about women? Women don’t have a Y chromosome. Women have two X chromosomes. Key for this tutorial: X H = Dominant healthy X h = recessive disease X H Y = healthy X h Y = disease What about my Y chromosome? If my Y chromosome is “healthy” and my X chromosome has a “disease”, will I be healthy? No correct

Men? Women? Both?:

BACK HOME Men? Women? Both? Women could have 1 of 3 different combination of X chromosomes. Key for this tutorial: X H = Dominant healthy X h = recessive disease

Men? Women? Both?:

BACK HOME Men? Women? Both? If both her X chromosomes have healthy alleles, she will be healthy. Key for this tutorial: X H = Dominant healthy X h = recessive disease X H X H = healthy

Men? Women? Both?:

BACK HOME Men? Women? Both? If both her X chromosomes have the allele for disease, she will have a disease. Key for this tutorial: X H = Dominant healthy X h = recessive disease X h X h = disease X H X H = healthy

Men? Women? Both?:

BACK HOME Men? Women? Both? But if she is heterozygous, she will be healthy. Women have a “backup” X chromosome in case their other has a recessive disease. This is the reason why sex-linked diseases in women is very rare. Men don’t have this advantage. Girl Power! Key for this tutorial: X H = Dominant healthy X h = recessive disease X H X H = healthy X H X h = healthy (carrier) X h X h = disease

Three Families:

BACK HOME Three Families Here are three families. Each of them has a history of a sex-linked disorder. They need your help because they hope to have children in the near future. Click the Guzman Family to start. The Jackson Family The Guzman Family The Chang Family

The Guzman Family:

BACK HOME The Guzman Family Hemophilia is a sex-linked recessive disorder found on the X chromosome. Sufferers of hemophilia lack a protein that helps their blood coagulate (clot) when injured. Thus, the person can lose a lot of blood from very minor injuries. Click on the vein to continue.

The Guzman Family:

BACK HOME The Guzman Family Hemophilia is a sex-linked recessive disorder found on the X chromosome. Sufferers of hemophilia lack a protein that helps their blood coagulate (clot) when injured. Thus, the person can lose a lot of blood from very minor injuries. Mr . Guzman is a hemophiliac. What is his genotype? X H Y X h Y Correct. He does not have a “backup” X chromosome. The capital H would mean he would be healthy. But the story says he is a hemophiliac.

The Guzman Family:

BACK HOME The Guzman Family Hemophilia is a sex-linked recessive disorder found on the X chromosome. Sufferers of hemophilia lack a protein that helps their blood coagulate (clot) when injured. Thus, the person can lose a lot of blood from very minor injuries. Mrs . Guzman is healthy with no family history of hemophilia. What is her genotype? X H X H X H X h X h X h Mr. Guzman’s Genotype: X h Y Capital H is healthy. Lowercase h is the disease. If she was X h X h , then she would have the disease. She has “no history of hemophilia” in her family. If she has a X h that would mean it runs in her family. Correct. She must be homozygous dominant.

The Guzman Family:

BACK HOME The Guzman Family So lets fill in the Punnett square below. Ladies first. X h Y X H X H

The Guzman Family:

BACK HOME The Guzman Family Now it’s Mr. Guzman’s turn. X h Y X H X H X H X H

The Guzman Family:

BACK HOME The Guzman Family Now it’s Mr. Guzman’s turn. X h Y X H X H X H X H X h Y continue

The Guzman Family:

BACK HOME The Guzman Family Now it’s Mr. Guzman’s turn. X h Y X H X H X H X H X h Y

The Guzman Family:

BACK HOME The Guzman Family Now it’s Mr. Guzman’s turn. X h Y X H X H X H X h X H X H X h Y

The Guzman Family:

BACK HOME The Guzman Family Now it’s Mr. Guzman’s turn. X h Y X H X H X H X H X h Y X H X H X h Y

The Guzman Family:

BACK HOME The Guzman Family Now it’s Mr. Guzman’s turn. X h Y X H X H X H X H X H X h X h Y X H X H X h Y

The Guzman Family:

BACK HOME The Guzman Family Now it’s Mr. Guzman’s turn. X h Y X H X H X H X H X H X H X h X h Y Y X H X H X h Y There are 2 squares that show a healthy boy. Click on each of them. Healthy boy Healthy boy

The Guzman Family:

BACK HOME The Guzman Family What is the probability of having a child, boy or girl, with hemophilia? X h Y X H X H X H X H X H X H X h X h Y Y X H X H X h Y 0% 25% 50% 75% 100% I have good news. Even though Mr. Guzman has hemophilia, none of your children will be hemophiliacs. But there is something to worry about… If you have daughters, they will be carriers of hemophilia. They can pass the gene to their children.

The Guzman Family:

BACK HOME The Guzman Family Thank you very much for your help doctor.

The Guzman Family:

BACK HOME The Guzman Family This information helps to ease the stress of starting a family.

The Guzman Family:

BACK HOME The Guzman Family You’re so very welcome. Please excuse me. I have another family to meet with.

The Jackson Family:

BACK HOME The Jackson Family The Jackson Family Colorblindness is a sex-linked recessive disorder found on the X chromosome. Colorblindness is the inability to perceive differences between some of the colors that other people can distinguish. Normal vision Colorblindness

The Jackson Family:

BACK HOME The Jackson Family Colorblindness is a sex-linked recessive disorder found on the X chromosome. Colorblindness is the inability to perceive differences between some of the colors that other people can distinguish. Remember that women have two X chromosomes. Because the disorder is recessive, a woman needs two recessive alleles to inherit the disorder. The Jackson Family

The Jackson Family:

BACK HOME The Jackson Family Colorblindness is a sex-linked recessive disorder found on the X chromosome. Colorblindness is the inability to perceive differences between some of the colors that other people can distinguish. Remember that women have two X chromosomes. Because the disorder is recessive, a woman needs two recessive alleles to inherit the disorder. Mr . Jackson is colorblind. What is his genotype? X H Y X h Y Correct. He does not have a “backup” X chromosome. Mr. Jackson is colorblind and that’s recessive. Recessive letters are lowercase. The Jackson Family

The Jackson Family:

BACK HOME The Jackson Family Colorblindness is a sex-linked recessive disorder found on the X chromosome. Colorblindness is the inability to perceive differences between some of the colors that other people can distinguish. Remember that women have two X chromosomes. Because the disorder is recessive, a woman needs two recessive alleles to inherit the disorder. Mrs . Jackson has normal vision, but her father was colorblind. Therefore her father passed her a copy of the colorblind allele . What is her genotype? Mr. Guzman’s Genotype: X h Y X H X H X H X h X h X h If she was this, she would be colorblind. But her father was colorblind and would pass his X h to her correct The Jackson Family

The Jackson Family:

BACK HOME The Jackson Family So let’s complete their Punnett square. X h Y X H X h X h Y X H X h

The Jackson Family:

BACK HOME The Jackson Family So let’s complete their Punnett square. X h Y X H X h X h Y X H X h Which genotype goes inside this square? X H X H X H Y X h Y X H X h X h X h

The Jackson Family:

BACK HOME The Jackson Family So let’s complete their Punnett square. X h Y X H X h X h Y X H X h X H X h Which genotype goes inside this square? X H X H X H Y X h Y X H X h X h X h

The Jackson Family:

BACK HOME The Jackson Family So let’s complete their Punnett square. X h Y X H X h X h Y X H X h X H X h Which genotype goes inside this square? X H X H X H Y X h Y X H X h X h X h X h X h

The Jackson Family:

BACK HOME The Jackson Family So let’s complete their Punnett square. X h Y X H X h X h Y X H X h X H X h Which genotype goes inside this square? X H X H X H Y X h Y X H X h X h X h X h X h X H Y

The Jackson Family:

BACK HOME The Jackson Family Great job. Now let’s analyze the Punnett square. Click on the genotype of a colorblind girl. X h Y X H X h X h Y X H X h X H X h X h X h X H Y X h Y Colorblind girl Normal vision girl Normal vision boy Colorblind boy correct

The Jackson Family:

BACK HOME The Jackson Family What is the probability of having a child (boy or girl) with normal vision? X h Y X H X h X h Y X H X h X H X h X h X h X H Y X h Y correct 0% 25% 50% 75% 100% Normal vision Normal vision

The Jackson Family:

BACK HOME The Jackson Family Even if your children are colorblind, there’s really nothing to worry about. There’s no negative health effects.

The Jackson Family:

BACK HOME The Jackson Family I may be colorblind, but I can see my beautiful wife. Thank you doctor.

The Chang Family:

BACK HOME The Chang Family The Chang Family Muscular Dystrophy is a sex-linked recessive disorder found on the X chromosome. The muscles of sufferers begin to deteriorate at an early age leaving the individual weakened and largely immobile. Death by mid-20s is common.

The Chang Family:

BACK HOME The Chang Family The Chang Family Muscular Dystrophy is a sex-linked recessive disorder found on the X chromosome. The muscles of sufferers begin to deteriorate at an early age leaving the individual weakened and largely immobile. Death by mid-20s is common. Mrs. Chang has a history of muscular dystrophy in her family and as a result they are considering adoption as an alternative. Because the disorder is recessive, a woman needs two recessive genes to inherit the disorder . Can you help?

The Chang Family:

BACK HOME The Chang Family The Chang Family Muscular Dystrophy is a sex-linked recessive disorder found on the X chromosome. The muscles of sufferers begin to deteriorate at an early age leaving the individual weakened and largely immobile. Death by mid-20s is common. Mrs. Chang has a history of muscular dystrophy in her family and as a result they are considering adoption as an alternative. Because the disorder is recessive, a woman needs two recessive genes to inherit the disorder . Can you help? Mr . Chang is healthy with no history of muscular dystrophy. What is his genotype? X H Y X h Y The story says Mr. Chang is healthy. If he was X h Y he would have the disease. Correct. X H means he would be healthy.

The Chang Family:

BACK HOME The Chang Family Mr. Chang X H Y Muscular Dystrophy is a sex-linked recessive disorder found on the X chromosome. The muscles of sufferers begin to deteriorate at an early age leaving the individual weakened and largely immobile. Death by mid-20s is common. Mrs. Chang has a history of muscular dystrophy in her family and as a result they are considering adoption as an alternative. Because the disorder is recessive, a woman needs two recessive genes to inherit the disorder . Can you help? Mrs . Chang is healthy even though she carries the recessive allele for muscular dystrophy. What is her genotype? X H X H X H X h X h X h If she was this, she wouldn’t be healthy. The story says she is a “carrier” correct

The Chang Family:

BACK HOME The Chang Family Mr. Chang X H Y Lets complete their Punnett Square. Mrs. Chang X H X h Mrs. Chang

The Chang Family:

BACK HOME The Chang Family Mr. Chang X H Y Lets complete their Punnett Square. Mrs. Chang X H X h X H X h Mr. Chang

The Chang Family:

BACK HOME The Chang Family Mr. Chang X H Y Lets complete their Punnett Square. Mrs. Chang X H X h X H Y X H X h

The Chang Family:

BACK HOME The Chang Family Mr. Chang X H Y Lets complete their Punnett Square. Mrs. Chang X H X h X H Y X H X h X H X H

The Chang Family:

BACK HOME The Chang Family Mr. Chang X H Y Lets complete their Punnett Square. Mrs. Chang X H X h X H Y X H X h X H X H X H X h

The Chang Family:

BACK HOME The Chang Family Mr. Chang X H Y Lets complete their Punnett Square. Mrs. Chang X H X h X H Y X H X h X H X H X H Y X H X h

The Chang Family:

BACK HOME The Chang Family Mr. Chang X H Y Mrs. Chang X H X h X H Y X H X h X H X H X H Y X h Y X H X h What is the probability the Chang’s have a child with muscular dystrophy? correct 0% 50% 25% 75% 100%

The Chang Family:

BACK HOME The Chang Family Mr. Chang X H Y Mrs. Chang X H X h X H Y X H X h X H X H X H Y X h Y X H X h Click the square below that would lead to a child with muscular dystrophy. Muscular dystrophy correct

The Chang Family:

BACK HOME The Chang Family X H Y X H X h X H X H X H Y X h Y X H X h You have an important decision to make. Muscular dystrophy

The Chang Family:

BACK HOME The Chang Family X H Y X H X h X H X H X H Y X h Y X H X h You have a 25% of having a boy inherit this disease. Muscular dystrophy

The Chang Family:

BACK HOME The Chang Family X H Y X H X h X H X H X H Y X h Y X H X h If that happens, he will not likely live past his 20’s. Muscular dystrophy

The Chang Family:

BACK HOME The Chang Family X H Y X H X h X H X H X H Y X h Y X H X h But there is a 75% chance that every child will be fine. Correct? Muscular dystrophy

The Chang Family:

BACK HOME The Chang Family X H Y X H X h X H X H X H Y X h Y X H X h That’s correct. However, I wanted you to know the probability. Muscular dystrophy

The Chang Family:

BACK HOME The Chang Family X H Y X H X h X H X H X H Y X h Y X H X h Thank you doctor. We will discuss this information and perhaps consider adoption. Muscular dystrophy

Conclusion:

BACK HOME Conclusion This is different from my pea plant experiments. The genes to give pea plants their color and texture are not found on the sex chromosomes.

Conclusion:

BACK HOME Conclusion It turns out that the pea plant characteristics I studied are found on nonsex chromosomes, or autosomes.

Conclusion:

BACK HOME Conclusion Only genes and traits that can be found on the X or Y chromosome are called sex-linked.

Conclusion:

BACK HOME Conclusion Most of these disorders are recessive, which means that women are less likely to suffer from the disorder because woman has a “backup” X chromosome.

The End:

The End BACK HOME End Tutorial

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