why is it that hemophilia is passed from mother to son and not from father to son?
492445
Because it's on the X-linked. And a boy has the chromosome of XY. The mother always passes an X to the son. And the day, a Y chromosome. If the father were to pass an X chromosome, the child would be a daughter.
447010
Hemophilia is group of hereditary bleeding disorders of specific blood clotting factors. There are two main types of hemophilia: A and B.\n\nWhat causes Hemophilia?\n\nHemophilia is caused by an inherited sex-linked recessive trait. The defective gene is located on the X chromosome.\n\nThe severity of symptoms can vary with this disease, and the severe forms become apparent early on. Bleeding is the hallmark of the disease and typically occurs if an infant is circumcised. Additional bleeding manifestations make their appearance when the infant becomes mobile. Mild cases may go unnoticed until later in life when try occur in response to surgery or trauma. Internal bleeding may happen anywhere, and bleeding into joints is common. Risk factors are a family history of bleeding and being male.\n\nWhat are the Symptoms?\n\nSome of the symptoms are: bruising, spontaneous bleeding, bleeding into joints and associated pain and swelling, gastrointestinal tract and urinary tract hemorrhage, blood in the urine or stool, excessive and prolonged bleeding from cuts, tooth extraction, surgery bruises that are unusual in location or number, nosebleeds that won't stop, and painful or swollen joints\n\nHow is Hemophilia Diagnosed?\n\nDoctors diagnose hemophilia by performing a set of blood tests. Coagulation studies involving many tests are performed if the person tested is the first one in the family to have a bleeding disorder. Once the defect has been identified, other family members will need less testing to diagnose the disorder.\n\nMedical Complications?\n\nSome of the medical consequences from hemophilia are: Chronic joint deformities, Intracerebral hemorrhage is another possible complication.\n\nCan Hemophilia be Cured?\n\nCurrently, there is no cure for hemophilia. However, it can be managed with medications, such as: clotting factor replacement therapy.
220614
Well, in scientific form this is caused by the Mendelian trait, Law of Dominance. One trait (Btwn any of your parents)is more dominant than the other. It can also be caused by sex-linked traits found in the x-chromosome. There are characteristics that the daughter will get that is diff. from the son. It is just normal. I too look more like my dad.
721123
Marfan's is a genetic disorder.  It's dominant, so the gene can be received from either parent, but it doesn't have a high penetrance, so just carrying the gene doesn't mean you will develop Marfan's.  The mutation also seems to arise spontaneously, so that about 30% of those with Marfan's did not receive a damaged gene from either parent.
638300
The answer is D because dad is hemizygous dominant and mom is heterozygous since both are normal. The kid got the Xt from mom and Y from dad. The kid couldn't get the bad gene from dad because if dad had it to give, then dad wouldn't be normal.
556328
Yes.  Your child may be A+, O+, A-, or O-.  The + part of the blood type is dominant to -.  You and your husband would have to each have a + from one parent and a - from the other parent in order for your child to receive 2 - genes and have rh- blood.  Having a different bloodtype than your child can lead to serious complications, especially during the second pregnancy.  If during the birth of your first child, your body is exposed to your baby's blood (and the blood is a different type than your own), you may build up antibodies to your baby's blood.  If your next child has the same bloodtype as your first child, your body may actually attack the baby.  Be sure to talk to your doctor about bloodtype dangers.
718212
dr d is correct.\n\nIt is transfer of genes within a generation, as compared to transfer from the parental generation to the offspring generation; that is vertical gene transfer between generations.\n\nIf genes are picked up from a cell in some way, and put into other cells (not involving cell division), then the genes have been transferred "horizontally".\n\nAn example is when a bacterium carrying a certain plasmid grows a "sex pilus", which then connects with the cell wall of a bacterium that does not carry that plasmid.  It will inject a copy of the plasmid, via the sex pilus, and the recipient has then become a carrier, too.  These plasmids often carry extra genes, as well as those coding for this ability.  These phenomena are sometimes considered to be similar to sex, but are really more like catching a virus!
455970
I don't have it, but I do know that when it is a familial disorder, it virtually always passes from mother to children, as it is a mitochondrial disorder, and all cellular organelles come from the mother's egg (the sperm basically supply just the DNA).  It can occur sporadically.  It is a A3243G mutation in the mitochondrial genetic code.  A good resource for the "technical" information.  http://www.emedicine.com/ped/topic1406.htm
868605
They share just about everything - size, morphology (metacentric, submetacentric or acrocentric) and banding pattern at metaphase (see http://members.aol.com/chrominfo/geninfo.htm for a nice quick explanation of these things).\n\nWhat will not be shared will be minute variations in the exact sequence of the DNA, given that half of the sequence will orginate from the mother and half from the father. These genetic differences account for phenotypic (physical) differences following expression of all the genes and contribute to the fact that your parents are not identical.
1065942
in old theoryit might seem that way, but not in real science. many genes and mutations can occurr without any generations having it or even skip generations. the structures of dna and genes have just been discovered to have millions of chromozones in each gene. enviroment has alot to do with genetics also. i have what is called factor v lieden. its a very rare mutation in my dna genes which causes blood clots all the time. at the va hospital, i found i was one of four known in the va system by the chief of staff to have it. they checked for genetics at first but no one in my family ever had a blood clot. just as in aids. there have been many children born from parents who were hiv and never got it. in your theory, the child could get nothing or the fathers 25 %. at what percent were the great, great grandparents. both 100 % or 50/50? the child could also get the great grandparents percentage which is the fathers. even with the mother at 75 and the father at 25. the child could get nothing, the fathers 25 percent or half of his or half of the mothers or half of both.
815639
DNA is in chromosomes. Chromosomes are in 23 pairs: 2 *different* copies of Chromosome 1, 2 different copies of C2, etc, in each person.  Whether you get your father's Chromosome 1 that he got from his mother, or the one he got from his father, is random with respect to which Chromosome 2 you get from your father. Same goes for your siblings. The chances of two nontwin siblings getting the same exact set of 23 5chromosomes from one parent are vanishingly small. The chances of siblings getting the same exact set of 23 chromosomes from EACH parent are .. well, it's essentially impossible. \n\nSame goes for the possibility that they would receive NO chromosomes in common - although it is theoretically possible to have siblings that share no genetic relation at all.\n\nDNA evidence is never 100% conclusive, but the tests that are widely used (if done properly) have such a small possibility of being wrong that they might as well be 100% conclusive. That's because there's just so much genetic material in any one person, it averages out ... makes it so that siblings are actually very close to 50% alike - even though they could be anywhere from 0 to 0% alike, in theory.
617814
because it's a recessive sex linked gene carried on the x chromosome.  therefore, since men are XY, if the mother passes down the gene on her X chromosome, he will have colorblindness.  if the mom passes it on to a daughter, the father, who also contributes an X, will most likely have the dominant, normal sighted gene on it and the color blindness won't present itself.
219241
Scientists have reported that they've found an "extremely unusual" trait in the cells of some mothers with two or more gay sons, providing more evidence to suggest that homosexuality might be inherited.\n\n\nMothers of multiple gay sons were about six times more likely than other women to process their X chromosomes in a certain way, researchers discovered.\n\n\nResearchers aren't entirely sure what the findings mean, said study co-author Sven Bocklandt, a postdoctoral researcher at UCLA. Making things more complicated, about 75 percent of mothers of multiple gay sons don't have the trait.\n\n\nStill, the study, released Tuesday in the journal Human Genetics, raises plenty of questions, Bocklandt said, especially as researchers try to figure out whether homosexuality has genetic roots and if there truly is a "gay gene" -- or genes.\n\n\n"What everybody wants is the gene, and we don’t have it yet," Bocklandt said. "But this is an independent confirmation that the X chromosome is involved."\n\n\nBocklandt and colleagues looked at a phenomenon known as X-chromosome inactivation, in which cells inside the bodies of females automatically turn off -- or inactivate -- one of their two X chromosomes. That leaves them with one working X chromosome -- just like males, who have a single X and a single Y chromosome.\n\n\nNormally, each cell in a female's body randomly turns off one or the other X chromosome. In some cases, such as when families share a genetic disease, there is "extreme skewing" -- one X chromosome is more likely to be turned off than the other, Bocklandt said.\n\n\nIn the new study, the researchers looked at 97 mothers of one or more gay sons and 103 women with no gay sons to see what their blood cells did with their X chromosomes. The researchers recruited many of the women with the help of PFLAG.\n\n\nThey found that nearly a quarter of the mothers of multiple gay sons inactivated the same X chromosome -- in other words, nonrandomly -- compared to just 4 percent of the women without gay sons. Of those with one gay son, 13 percent inactivated the same X chromosome.\n\n\nDr. Ionel Sandovici, a genetics researcher at the Babraham Institute in Cambridge, England, who is familiar with the research findings, cautioned that the study is small, with just 44 mothers of multiple gay sons being examined. More research in larger groups must be done to confirm the results, Sandovici said.\n\n\nThe research does provide "circumstantial evidence" that the X chromosome contributes to the development of male sexuality, Sandovici said. But "we still understand very little about molecular mechanisms of sexual orientation, and this seems to be rather a complicated biological puzzle."\n\nBut of course its Nature vs. Nurture and its possible that the person could just become gay because of his environment/experiences or just be born that way.
724848
Haemophilia or hemophilia is the name of any of several hereditary genetic illnesses that impair the body's ability to control bleeding. Genetic deficiencies (or, very rarely, an autoimmune disorder) cause lowered plasma clotting factor activity so as to compromise blood-clotting; when a blood vessel is injured, a scab will not form and the vessel can continue to bleed excessively for a very long period of time. The bleeding can be external, if the skin is broken by a scrape, cut or abrasion, or it can be internal, into muscles, joints or hollow organs. It might therefore present visibly as skin bruises, or subtly as melena, hematuria, or bleeding in the brain-.
515107
Simply put: Obligatory carriers are of normal phenotype but have a parent that has a particular recessive disease that they carry and therefore are at risk of passing the trait on to their offspring.\nMore comprehensively put: Obligatory carrier is usually referred to in recessive diseases.  It means that the person MUST be a carrier of a particular trait.  For example hemophilia is a sex-linked recessive disease.  If a man is born with hemophilia, all of his daughters automatically have to be carriers of the disease.  This is because they have to get the X with the trait on it from their father.  Now it is up to the mother whether the daughter will have hemophilia.  If the mother is a carrier there is a 50/50 chance that the daughter will be a carrier or have the disease.  If the mother is homozygous dominant then the daughter can only be a carrier.  In autosomal recessive disease, if a parent has a recessive disease then all of their children must either carry the trait or have the disease because the parent with the disease can only give that trait to their child.  It is up to which allele they get from the normal parent as to whether they have the disease.
927834
To answer this question you must look at it through a punnet square.\n\nMother- I^A I^B\nFather- I^A I^A OR I^A i  (i = Type O)\n\nThe mother being Type AB defines for us each of the alleles that make up here blood type: I^A and I^B.  \n\nThe father being Type A provides only one clue: that he has at least one A allele.  Because an A allele will mask an O allele, it is impossible to know whether or not he has homozygous for Type A blood (I^A I^A) or if he is heterozygous for Type A blood (I^A i).  Even as a heterozygote, the father will express Type A blood.  \n\nFor this reason you must create two separate Punnet Squares.  In one the father's genotype will be I^A I^A and in the other his genotype will be I^A i.  In both the mother's alleles will remain constant with I^A and I^B.  \n\nYou will realize, however, that because the mother has no Type O allele (i), there is no possibility that any of their offspring will have Type O blood.  This is because Type O blood only appears when both alleles are for Type O (i i).  Since the father has possibly one O allele, and the mother has no O allele, a homozygous genotype for Type O blood cannot happen.\n\nGood luck!
1043295
Hemophilia is a sex linked disorder. Meaning it's passed from the female carrier to the male child. It's carried on the female X chromosome, when an egg, being an X, is met with a Y sperm because there is no second X to cancel out the carrier X. The result is hemophilia, given this only happens if the egg is already a carrier.\n\nXX= female... the X's cancelled each other out\nXY= male... the disorder is dominant because there is nothing to cancel it out.\nThat is why women RARELY get hemophilia\n\nI hope that's not too confusing.