Sometimes, things don’t always follow Mendel’s Laws Write the following in your notes: I can predict an outcome of a cross using incomplete dominance and codominance. 1. Science Starter 2 2. 3. 3 1. 4 2. 3. 5 Codominance In some instances, certain traits are codominant. That means that one trait cannot win out over the other form of the trait. In the offspring, both traits show up equally. Genotype RW Genotype WW Genotype RR With Codominance…. BB BW WW Yo, girl. ‘Sup? WW RR RW In cows, this red & white pattern is known as roan. T BT TT BT BT A cross between a tan cat (TT) and a black cat (BB) results in a third phenotype we refer to as a “Tabby.” Blood also provides us with a great example of co-dominance. There are four types of blood: A, B, AB, and O. A & B are co-dominant while O is always recessive (though seldom written as a lower case letter.) If a person with homozygous B blood crosses with a person with homozygous A blood, the genotypes for the offspring will be AB. o o B o A A A A B B o A B o o o Type O blood is like any other recessive trait. The only way a child can be born with type O blood is if both parents have at least one recessive O allele in their genotype. The different types of blood are not necessarily interchangeable. If you give someone the wrong blood during a transfusion, it can result in serious medical problems and potentially even death. When incompatible blood is mixed it clumps together and forms clots. A person with blood Type A can receive Type A blood and Type O blood. Why is Type O not a threat to the body? It does not have antigens, so it is not read as a threat. A person with blood Type B can receive Type B blood and Type O blood. Why is Type O not a threat to the body? It does not have antigens, so it is not read as a threat. A person with blood Type AB can receive Type AB blood, Type A blood, Type B blood, and Type O blood. A person with Type AB is known as a universal recipient. A person with blood Type O can only receive blood from others with blood type O. However, since any recipient can receive O blood, a person with O blood is called a universal donor. CLOSING 1. If a child has type O blood, what must be true about the parents? a. both parents must have genotype oo b. at least one of the parents must have genotype oo c. both parents must have at least one recessive o allele d. at least one parent must have one recessive o allele 2. If Kristina has blood AO and her husband has blood type BB, what are the possible blood genotypes for their children? a. BO, AB b. B, BB c. AB, AA d. all of the above 3. Ava’s parents both have type O blood. What must Ava’s blood type be?__________ a. it depends on the genotypes of her parents b. Ava’s parents must be oo, so she must also have oo. c. Ava could have any blood type because O is the universal blood type d. Ava can have any blood type except O 4. Which of the following is a genetic characteristic that Kaila could have inherited from her parent? A. scars from a bicycle accident B. the color of his hair C. the ability to bowl well D. his handwriting ability 5. Shawn and Charlie are exploring a remote part of the Taklimakan Desert when they discover a new species of beetle. Of the beetles they observed, about 723 had long jaws and 250 had short jaws. What can we infer about the genes for jaw shape? a. The form of the gene for long jaws is recessive b. The form of the gene for short jaws is co-dominant c. The forms of the gene for long jaws is dominant d. There is no way of telling from these observations Day 2 I can predict an outcome of a cross using incomplete dominance and codominance. 1. 2. Science Starter 16 3. 4. 17 5. In humans, the form of the gene for brown hair (B) is dominant over the form of the gene for red hair (b). If two people with brown hair have children, what can we predict about their offspring? 1. 2. 19 3. 4. 20 5. In humans, the form of the gene for brown hair (B) is dominant over the form of the gene for red hair (b). If two people with brown hair have children, what can we predict about their offspring? Since we don’t know the exact phenotype of the parents, we cannot say for sure that the offspring will have brown hair. If both parents have genotype Bb, for example, then there is a 25% chance that an offspring will have a different hair color. The best we can say is that the offspring will most likely be born with brown hair. Incomplete Dominance In other instances, two forms of a gene have incomplete dominance. That means that when the two genes compete, neither wins outright. Instead, the phenotype of the offspring present a mixture of the two traits. For example, if in a particular flower species Red and White were co-dominant, a mix of the two would result in pink flowers, white flowers with red stripes, or red flowers with white stripes. Since the colors Red and White are co-dominant or have incomplete dominance over each other, the genotype for a pink flower is NOT written as P, but as RW. A Punnett square showing what would happen if you crossed a red flower with a white flower would look like this. R R W RW RW W RW RW RW does not mean that each of the offspring has both red and white in the flowers. That would be codominance. Incomplete dominance means that a blend of the two colors shows up as the phenotype. In this case, red and white blend to make pink. The phenotype for genotype RW is pink. Cross of two purple flowers RB X ____ RB ____  What are gamete possibilities?  genotype ratio R 25% RR 50% RB 25% BB RR  phenotype ratio R 25% red 50% purple 25% blue  Can you have a heterozygous red or no hybrid blue flower? ___ B red RB purple B RB purple BB blue 1. Suppose the allele for black fur (B) and white fur (W) have incomplete dominance in a small rodent. What percentage of the offspring will be gray if a black rat mates with a white rat? 100% 2. Suppose the allele for black fur (B) and white fur (W) are codominant in a small rodent. What percentage of the offspring will be white if a black rat mates with a white rat? This is a trick question….;) 3. A Punnett square showing what would happen if you crossed two pink flowers would look like this. R W R RR RW W RW WW How many of these offspring would be pink? 50% How many would be white? 25% How many would be red? 25% 4. A tabby cat is a cross between a black cat and a tan cat. The tabby cat’s coloring demonstrates__________________. a. That black is dominant over tan b. That tan is dominant over black c. That black and tan are co-dominant d. That black and tan have incomplete dominance 5. A cross between white snapdragons (W) and red snap dragons (R) produces snapdragons that are pink. What would be the genotype for the pink snapdragons? a. PP b. WP c. RW d. PR 6. This is an example of: a. Incomplete dominance b. Complete dominance c. Co-dominance d. Co-recessive traits 7. Josh has a square head like Frankenstein that is caused by a recessive form of the head-shape gene (o). Oval shaped heads (O) are dominant. Josh doesn’t like his Frankenstein head, so he wants to make sure that none of his children are born with this trait. What must he do to ensure none of his children have Frankenstein head? a. Only marry and have children with a woman who is heterozygous for oval head. b. Only marry and have children with a woman who is homozygous for oval head. c. Marry and have children with any woman who has the oval head phenotype. d. Not worry because recessive traits can only be passed down if the woman carries them 8. Haye’s parents have blood genotypes AO and AB. Hayes could have any blood type except: a. A B. B c. AB d. O 9. Mendel’s experiments demonstrated that any time two hybrids are cross- bred the recessive trait will appear in the phenotype of ___________% of the offspring. a. 100% b. 75% c. 50% d. 25% 10. The four blood types are _________________________ a. A, C, B, O b. A, B, O, OO c. A, B, AB, O d. A, B, C, and D 11. Which blood type(s) are dominant? a. A, O b. B, O c. A, B d. just O 12. If the genes for black (B) and white (W) feathers on a particular species of bird show incomplete dominance, what would be the genotype for gray feathers? a. GG b. BG c. BW d. WG 13. If a male pigeon has gray feathers and his mate has black feathers, what phenotypes are possible in their children? (B- Black, W-White) a. black, gray, or white feathers b. black or white feathers c. black or gray feathers d. white or gray feathers 14. Werewolves who are purebred for the werewolf gene (WW) can turn into werewolves any time they want to. Werewolves who are hybrid for the werewolf gene (Ww) can only change into werewolves on the night before, during, and after a full moon. If a female purebred werewolf breeds with a hybrid male and they have 12 pups, how many of the pups will be purebred werewolves? a. 0 b. 2 c. 3 d. 6 15. Mr. Chip enjoys breeding orchids because of the enormous challenge involved. Part of the fun is trying to cross orchids with different colored flowers to create new hybrids. In one experiment, he bred a maroon orchid with a gold orchid and produced orchids with this color and pattern which he called Royal Benjamin. This pattern demonstrates: a. Incomplete dominance b. Co-dominance c. Complete dominance 16. If Mr. Chip wanted to breed and sell only Royal Benjamin hybrid orchids, what should he do to ensure he produces the most Royal Benjamin hybrids possible? a. Breed Royal Benjamins with only gold orchids. b. Breed Royal Benjamins with only maroon orchids. c. Breed Royal Benjamins only with Royal Benjamins. d. Breed only gold orchids with maroon orchids. 17. When a farmer cross breeds a purebred white cow with a purebred red cow, this color pattern (known as roan) results: What can we infer about the genes controlling fur color in this breed of cattle? a. Red and white are co-dominant. b. Red and white have incomplete dominance. c. White is dominant over red since more of the cow is white than red. d. Red is dominant to white since the head of the cow is mostly red. Special Note: Many cattle and horse breeders consider the roan pattern an example of incomplete dominance. I am not going to go into how or why, but if you see it listed as such, go with it. 18. Bubba has type A blood. His wife, Betty-Lou, has type B blood. Their daughter, Violula has type O blood. How is this possible? a. Bubba has type AA and Betty Lou has type Bo. b. Bubba has type Ao and Betty Lou has type BB c. Bubba has type Ao and Betty-Lou has type Bo d. There is no way for the daughter to have type O blood. 19.Two horses that are gray-blue in color are bred. Over time, these two horses produced foals that were black, white, and gray-blue. 20. What can we infer about genes that regulate fur color in this breed of horse? a. Black and white have incomplete dominance b. Black is dominant over white c. Black and white are co-dominant d. Black is recessive to white Day 3 Write in your notes: I can recognize that selective breeding can produce plants or animals with desired traits. 1. Science Starter 2. 35 3. In the alien species known as dwarks, pig-noses (P) are dominant while pointy noses (p) are recessive. If a certain dwark (Dylan) has genotype Pp, what type nose does he have? a. Pointy b. Pig-nose c. A mix between pointy and pig-nose d. A completely different nose shape 36 4. In Gregor Mendel’s pea experiments, the purple flower color (P) was dominant over the white flower color. What genotype will result in the purple flower color? a. PP b. Pp c. pp d. both PP and Pp 5. The original vampires from Transylvania were purebred vampires (VV) meaning they were born vampires. A human bitten by a purebred vampire turns into a vampire-human hybrid (Vv). If two of these vampire hybrids (Cayleigh & Jake) breed, what percentage of their offspring will be born purebred vampires? a. 0% b. 25% c. 75% d. 100% 37 1. 2. 38 3. In the alien species known as dwarks, pig-noses (P) are dominant while pointy noses (p) are recessive. If a certain dwark (Reginald) has genotype Pp, what type nose does he have? a. Pointy b. Pig-nose c. A mix between pointy and pig-nose d. A completely different nose shape 39 4. In Gregor Mendel’s pea experiments, the purple flower color (P) was dominant over the white flower color. What genotype will result in the purple flower color? a. PP b. Pp c. pp d. both PP and Pp 5. The original vampires from Transylvania were purebred vampires (VV) meaning they were born vampires. A human bitten by a purebred vampire turns into a vampire-human hybrid (Vv). If two of these vampire hybrids (Cayleigh & Jake) breed, what percentage of their offspring will be born purebred vampires? a. 0% b. 25% c. 75% d. 100% 40 Selective Breeding Suppose a farmer has two types of corn. One type has small ears but big kernels. The other type has big ears but tiny kernels. The farmer may plant the two types of corn next to each other so that the pollen from each type of corn can fertilize the other type. What the farmer hopes is that some of the corn plants will develop ears of corn that are both big and that have big kernels too. This type of genetic cross pollination is known as selective breeding. Selective breeding is the process where humans try to isolate certain favorable traits in plants and animals by crossbreeding animals and plants of the same species but ones that have different forms of certain genes. Selective breeding has been done for thousands of years with both plants and animals. All domesticated cattle, horses, dogs, and cats are products of selective breeding. That is why there are so many “breeds” of these animals. Humans cross bred these animals in an attempt to isolate desired traits. Dogs such as Dachshunds and Bassett Hounds are a result of hunters trying to breed the “short leg” version of the gene for leg length into another breed of dog so that they could have a hunting dog that was short enough to chase rabbits through the maze of rabbit trails in a thicket of woods. SELECTIVELY-BRED DESIGNER FRUITS USDA created Carrots PINEBERRY PLUOT GOLDEN WATERMELON Double Muscling- Good Science or Animal Cruelty (STOP video at 3:30.) http://www.youtube.com/watch?v=rW54_vM9SF0 1. Mr. Moore grew two types of tomatoes in his back yard. One produced lots of small, sweet tomatoes. The other didn’t grow as many tomatoes but the ones that did grow were much larger. What might Mr. Moore hope to accomplish by cross-breeding these two types of tomatoes? By crossing these two tomato plants, he may eventually create a new hybrid tomato plant that produces lots of large, sweet tomatoes. 2. What process did Mr. Moore use to create his hybrid in question #1? Selective breeding. 3. Donovan is a rose grower. He grows mostly red roses, but occasionally some of his roses turn out pure white due to a recessive form of the flower color gene. Lots of people in his area produce red roses (and the few white roses that grow from time to time), but none of them grow only white roses. Donovan decides he can do better if he only produces white roses since there is less competition. What would he need to do in order to ensure his plants produced only white roses? Only breed white roses with other white roses. 4. Which of the following genetic traits might cattle farmers be interested in selectively breeding into their cattle? a. larger size (more meat per animal) b. less resistance to certain parasitic diseases c. larger ears to keep them cooler in summer d. muscle structure that allow them to run faster 5. In the sport of horse racing, race horse owners may pay $1,000,000 for the right to allow one of their horses to breed with a champion race horse. Their hope is that some of the genes that helped the champion become so successful will be selective breeding. passed on to the offspring. This is an example of _________________________ 6. The tiny Chihuahua and the Great Dane are both dogs. What is the best explanation for why these two breeds of dog differ so greatly? First of all, Chihuahuas aren’t dogs-they are rats that bark. Now that we have that out of the way, the answer is both dogs have been selectively bred by humans for specific physical traits. 7. In Nepal, male Yaks are bred with female domestic cows to create a hybrid animal that has good tasting meat and that can survive the high altitudes and selective breeding cold temperatures of Nepal. This is an example of ____________________. Day 4 Write in your notes: I can explain how genetic modification differs from selective breeding. 1. Science Starter 48 2. Unattached or “free” earlobes (E) are dominant. Attached earlobes (e) are recessive. Justin Bieber is heterozygous for unattached earlobes. Medeline has attached earlobes. What is the probability that a child of theirs will have attached earlobes? a. 0 % b. 50% c. 75% d. 100% 3. Kinsey and Caleb both have free earlobes. What prediction can we make about children they may have? a. The children will most likely have free earlobes b. The children will definitely have free earlobes c. The children will most likely have attached earlobes d. The children will definitely have attached earlobes 49 1. 50 2. Unattached or “free” earlobes (E) are dominant. Attached earlobes (e) are recessive. Justin Bieber is heterozygous for unattached earlobes. Medeline has attached earlobes. What is the probability that a child of theirs will have attached earlobes? a. 0 % b. 50% c. 75% d. 100% 3. Kinsey and Caleb both have free earlobes. What prediction can we make about children they may have? a. The children will most likely have free earlobes b. The children will definitely have free earlobes c. The children will most likely have attached earlobes d. The children will definitely have attached earlobes 51 Genetic ModificationGenetic modification refers to the science of gene manipulation. Genetic manipulation is far more precise that selective breeding. Scientists have discovered ways of removing particular genes or sections of DNA from one organism and seeding or planting those genes in another organism. This practice is most often done in agriculture. For example, scientists have taken the genes from some plants and seeded these genes into agricultural crops. Scientists have been able to develop hybrid crops. They have been able to develop corn that is more drought and pest resistant, tomatoes that have more vitamins, and rice and soybeans that have more nutritional value. The two organisms do not have to be the same species. In fact, sometimes the species are nothing alike at all. Genetic modification has resulted in a huge increase in the amount of food that can be grown. Many scientists see genetic modification as one means for solving hunger in many parts of the world. Genetic modification is not without its critics, however. Many people are concerned that manipulating genes can cause health problems in humans. Others believe that changing the genetics of corn can lead to problems with the corn genome. Genetically modified crops can produce better yielding and larger fruits like this eggplant… Future Rice Shortage Rice is the most important food source for billions of the world’s population. Unfortunately, as the population in these parts of the world continues to explode, the amount of area where rice is grown has not increased. If fact, it has decreased. For every one billion people added to the world’s population, 100 million tons of rice (paddy) need to be produced more annually. The increase in demand for rice coupled with the lack of increase in the supply also causes the price of rice to rise---something a poor population cannot adjust to. Where will this rice come from? Enter the genetically engineered “Super Rice.” Green Super Rice is actually a mix of more than 250 different potential rice varieties and hybrids variously adapted to difficult growing conditions such as drought and low inputs, including no pesticide and less fertilizer, and with rapid establishment rates to out-compete weeds, thus reducing the need for herbicides. Result: Green Super Rice • yields more tons of rice per acre •Can grow in places where rice could not previously grow •Requires fewer chemicals to control weeds and damage from insects •Contains more important vitamins like Vitamin A, zinc, and other nutrients which can dramatically decrease health issues related to malnutrition. 1. Genetic scientists at the University of Georgia crossed two breeds of cotton to create a cotton hybrid that has the insect resistance of one of the cotton parents and the drought resistance of the other parent. This is an example of _______________. a. selective breeding b. genetic modification c. automated breeding 2. A plant that grows wild in the Sonoran desert is resistant to most kinds of insects. Agricultural scientists were able to isolate the gene in the plant that gives it insect resistance and insert that gene into a variety of wheat to produce an insect-resistant wheat. This is an example of what genetic process? a. selective breeding b. genetic modification c. automated breeding 3. McIntosh apples are known for their crisp, sweet/tart flavor. McIntosh apple trees need about 800 chill hours in order to produce fruit the next year so they cannot grow in the Deep South. Certain varieties of crabapples need only 200 chill hours, but the fruit is small and does not have a very good taste. What might an apple grower hope to achieve by selectively breeding the McIntosh with the crabapple? The development of a hybrid apple that tastes great and requires only about 200-500 chill hours. 56 4. Buffalo (American Bison) are able to tolerate both hot and cold temperatures but their meat is not considered by many people to be as tender or as tasty as beef. Cattle generally have more tender, tasty meat, but the quality of their meat can be severely compromised if the cattle are exposed to wide fluctuations in temperature. Ranchers have cross bred cattle with buffalo/bison. What would be the ideal characteristics ranchers would want to isolate in the “Beefalo” hybrid? The ideal hybrid animal would have the tnederness of beef and the ability to tolerate a wide range of temperatures without damaging meat quality. 5. Seth raises Mountain Sheep for their wool. About 75% of the sheep are Golden (G) while 25% are brown (b). Carter comes to Seth’s town one day and tells him he has a huge market for brown wool clothing in Paris and will take all the brown wool Seth can produce. Not only that, but Carter says he will pay double for brown wool. What can Seth do to produce more brown sheep? Only cross-breed the brown sheep with other brown sheep. 6. Tomatoes selectively bred to grow in the relatively arid climates of Arizona will most likely not grow well in areas of high humidity like Georgia or Florida because fruit attacking fungi and bacteria survive so well here. How might scientists or tomato growers try to enhance the Arizona tomato so that it can grow successfully in Georgia? Scientists can try to cross-breed a tomato that has resistance to fungi with other tomatoes to produce a hybrid tomato with the fungi resistant trait. Scientists might also genetically modify a tomato by inserting a fungiresistance gene from some other breed of tomato or even another species of plant into the type of tomato growers wish to grow in Georgia. 7. Which of the following adaptations would be desirable for a farmer to selectively breed into a crop of corn? a. insect resistance b. drought tolerance c. higher vitamin content d. all of the above 8. In Maine, brook trout and salmon are cross-bred to produce a hybrid called a splake. In the south, small ponds are often stocked with bluegill hybrids that are a cross between a species of sunfish and a bluegill. In the larger lakes, striped bass are crossed with largemouth bass to produce the hybrid striped bass. Using your knowledge of hybrids that are crosses between different species, why might these hybrids be preferred to the purebred fish when it comes to stocking private ponds? a. the hybrid species reproduce faster than the purebred species so the pond fills up with fish quicker b. the hybrid species are healthier than the purebred species so they survive better c. the hybrids taste bad to predators like birds, other fish, and turtles so they don’t get eaten d. the hybrids cannot reproduce, so their population can be controlled much more easily and there is no chance they can take over a pond Other Rare Tran-species Hybrids Animal Hybrids A mule is the offspring of a male donkey and a female horse A tigon is a cross between a male tiger and a female lion. A liger is a cross between a male lion and a female tiger. Bactrian (two-hump) camels are native to the cool steppes of Asia. Dromedary (one hump) camels are hot desert dwellers. The F1 Bactrian-Dromedary hybrid camel is bigger, stronger, and hardier than either of the parents. Wolf hybrids Coydogs are crosses between dogs and coyotes. The Cama is the result of breeding a Llama to a Camel. Parents in background of picture. The Zebroid is the result of breeding a female Horse and a male Zebra. The Zedonk / Zonkey is the result of breeding a female Donkey and male Zebra. Day 5 Write in your agenda: I can recognize that changes in DNA (mutations) can result changes in organisms. 1. These control individual genetic traits: a. genes b. zygotes c. autotrophs d. chromosomes 2. Nearly all cells in complex organisms contain two forms of the same gene known as ______________. a. chromosomes b. alleles c. zygotes d. homophones 3. If the two alleles in a gene pair are the same form of the gene, that pair is: a. haploid b. heterozygous c. haploid d. homozygous 4. If the two alleles in a gene pair are different forms of the gene, that pair is: a. haploid b. heterozygous c. haploid d. homozygous 5. If an organism is heterozygous for a trait, it is also said to be ______________ for that trait. a. purebred b. haploid c. diploid d. hybrid 6. If an organism is homozygous for a trait, it is also said to be _______________ for that trait. a. purebred b. haploid c. diploid d. hybrid Science Starter 67 Genetic Disorders When DNA makes a copy of itself, a “checker” makes sure that the new copy is identical to the original. If a problem is identified in the new molecule of DNA, the checker either fixes it on the spot or destroys the new molecule and starts over. This is a very efficient system that almost never fails. Almost. A genetic disorder is a disease that is caused by an abnormality in an individual's DNA. Abnormalities can range from a small mutation in a single gene to the addition or subtraction of an entire chromosome or set of chromosomes. Some genetic disorders are inherited from a parent. Some of the genes that cause certain diseases are dominant, which means any child born to this parent stands a very high risk of inheriting the gene and thus contracting the disease. In the next few slides, we will review some of the more common types of genetic disorders and their causes. http://www.youtube.com/watch?v=xBynH-oCfJM Chromosomal Disorders Down Syndrome is a developmental disorder caused by an extra copy of chromosome 21. If a pair of number 21 chromosomes fails to separate during the formation of an egg (or sperm), then when the egg is fertilized by the sperm, the newly formed zygote ends up with three #21 chromosomes instead of two. Genetic Disorders Caused by Defects on Specific Genes Recessive Genetic Disorders Cystic fibrosis is a genetic disorder that affects the respiratory and digestive systems. People with cystic fibrosis inherit a defective gene on chromosome 7. This causes a thick mucous to continuously build up in the respiratory and digestive tract. Sickle cell disease– red blood cells are sickle shaped instead of round and cannot carry enough oxygen to the body tissues. Patients with sickle cell disease have a mutation in a gene on chromosome 11. The heterozygous form protects people from malaria Genetic Disorders Caused by a Dominant Form of a Gene Huntington's Disease (HD) is a brain disorder that affects a person's ability to think, talk, and move. Huntington’s disease is caused by a dominant gene that is passed on. The child of an adult with HD stands a 50% chance of inheriting the HD gene. Symptoms of Huntington’s Disease may not become noticeable until adulthood. Huntington’s attacks the nervous system causing gradual muscle paralysis and loss of cognitive ability (the ability to use your brain to think, understand things, process the world, communicate, etc.) Genetic Disorders Carried on Sex Chromosomes (X or Y) Red/Green Color Blindness is typically a recessive genetic condition, and it is much more common in men than in women. It is caused by a defect on the X chromosome. A male’s sex genotype is XY. A female’s is XX. If a male’s X chromosome has the red/green color blindness defect he will have the disorder since there is no normal form of the gene to balance it out. It is extremely rare that a woman would have the r/g CB defect on BOTH of her X chromosomes. If she has the red/green color blindness on one of her two X chromosome but the other X chromosome is normal, she will not experience color blindness. Remember, the defective trait is recessive, so the normal gene for that trait would win out. In this case, the woman considered a carrier of the r/g CB even though she does not have the disorder. Many people think anyone labeled as "colorblind" only sees black and white -- like watching a black and white movie or television. This is a big misconception and not true. It is extremely rare to be totally color blind. There are many different types and degrees of colorblindness - more correctly called color deficiencies. Color Blindness test: WITHOUT SPEAKING, please write down the numbers contained in the circles above and below. Hemophilia is another disorder that is carried on the X chromosome. Hemophilia is a bleeding disorder that slows the blood clotting process. People with this condition experience prolonged bleeding or oozing following an injury, surgery, or having a tooth pulled. In severe cases of hemophilia, heavy bleeding occurs after minor trauma or even in the absence of injury (spontaneous bleeding). Serious complications can result from bleeding into the joints, muscles, brain, or other internal organs. A women who is a carrier for hemophilia has the genetic mutation on one of her X chromosomes as illustrated below. She will have another non mutated X chromosome that will usually somewhat compensate for the defect in the other. It is not uncommon for women who carry the hemophilia gene to have low levels of clotting factor and have bleeding problems. A man who has hemophilia has the genetic mutation on his only X chromosome. He does not have another X chromosome to compensate for the defect so he will have hemophilia. X HX Y HXX daughter XY son X HXX daughter XY son 1.Eli travels to Africa and falls in love with a beautiful woman from the Congo Basin. In their discussion about marriage and having a family, she tells him that she is a carrier of the sickle cell gene (Ss). Eli doesn’t have the sickle cell trait at all (SS). What percentage of their children stand a risk of inheriting the “s” allele? a. 0% b. 50% c. 75% d. 100% 2. Sickle cell is a recessive trait (s). What is the probability that Eli and his wife will have children who are born WITH sickle cell? a. 0% b. 50% c. 75% d. 100% 3. What is the probability that one of their children will be a carrier of sickle cell? 0% b. 50% c. 75% d. 100% 4. Which of the following genetic disorders is a result of inheriting an extra #21 chromosome? a. Parkinson’s Disease b. Down Syndrome c. Sickle Cell Disease 5.Which of the following disorders is a result of a gene that is carried on the X chromosome? a. red/green color blindness b. Down Syndrome d. Sickle Cell