Question

chup is called the bleeder's disease because the affected person's blood is unable to clot. nougn hemophiliacs do bleed externally after an iniury they also suffer from internal bleeding pa around joints. Hemorrhages can be checked with transfusions of fresh blood (or plasia U protein. The most common type of hemophilia is hemophilia A, due to the absence or minimal presence of a particular clotting factor called factor VIII. 3. Make up a cross involving hemophilia that could be answered by a Punnett square, as in Figure 25.54 of . What is the answer to your genetics problem? Multiple Alleles When a trait is controlled by multiple alleles, the gene has more Protective clothing Wear protective than two possible alleles. But each person has only two of the pos- laboratory clothing, latex gloves, and sible alleles. For example, ABO blood type is determined by multi- goggles. If the chemicals touch the skin, eyes, or ple alleles: . 7". i. Red blood cells have surface molecules called mouth, wash immediately. If inhaled, seek fresh air. antigens that indicate they belong to the person. The allele causes red blood cells to carry an A antigen, the l" allele causes red blood cells to carry a B antigen, and the i allele causes the red blood cells to have neither of these antigens, and I are dominant to i. embering that each person can have any two of the possible alleles, these are possible genotypes henotypes for blood types. Genotypes Antigens on Red Cells Blood Types BB. Pi A/B A and B AB

I really don't understand number 3 for both questions

please and Thanks you

Answer 1

Hemophilia is an X-linked recessive disorder that results in the deficiency of factors IX or VIII. These factors are responsible for coagulating blood during either external or internal bleeding. Males are exclusively affected in X-linked inheritance pattern.

In mating between parents when the mother is a carrier of the disease and the father is normal, there are 50% chances of males being affected by the disease. The cross between a normal male and carrier female is shown below:

Parents xx# X X#Y Xb:X-chromosome carrying mutated gene for Hemophilia XH: X-chromosome carrying normal gene Gametes xbxH xH Y XbxH: Carrier female XHY : Normal male xh XH Xн хът XH XH Carrier female Normal female хь у Пхнү Affected male Normal male

In the above cross, one out of the two females is the carrier of the disease because the trait is X-linked recessive. In males, since they receive a Y chromosome from father and X from the mother, there are 50% chances that out of the two sons, one will be affected.

In case when the male is affected and the female is normal, all the daughters will be the carrier of the disease because they will be receiving affected X chromosomes from the father and a normal X-chromosome from the mother. The resulting genotype makes them a carrier of the disease. The cross, in this case, is shown below:

Parents xH xH X X Y Xb:X-chromosome carrying mutated gene for Hemophilia XH: X-chromosome carrying normal gene Gametes xH xH X Y XH XH xbyH: Carrier female XHY:Normal male XH XH : Normal female XbY: Affected male хи хът xHxh Carrier female Carrier female XHY XHY Normal male Normal male

Note: A female with a heterozygous genotype is considered a carrier of the disease because the trait is controlled by the recessive allele and thus, for a female to be affected, the genotype should be homozygous recessive. They can only transfer affected traits to the next generation. therefore, they are considered as the carrier.

b. The answer to this genetic problem is that, in the case of an X-linked recessive disease, a carrier mother can have 50% affected son when she mates with a normal female. If the mother is completely normal and her mating partner is affected, then all the females are found to be the carrier of the disease.