FIGURE 25.1 The albino phenotype in a human and a wildebeest. Genes-Traits Certain enzymes (encoded by genes) are necessary for the production of pigment. A homozygote with two defective alleles in one of these pigmentation genes exhibits an albino phenotype. This phenotype can occur in humans and other animals.

A 30 - year - old woman was undergoing therapy for b-thalassemia,a recessive trait caused by absence of or reduced synthesis ofthe hemoglobin b chain, a subunit of the oxygen-carrying moleculein red blood cells. In this condition, red blood cells are rapidlydestroyed, freeing a large amount of iron, which is deposited in tissuesand organs. The blood transfusions the patient had received every twoor three weeks since the age of 7 to stave off anemia were furtheraggravating iron buildup. Her major organs were showing damage, andshe was in danger of death from cardiac disease. Her physician suggestedthat she consider undergoing a hematopoietic (bone marrow)stem cell transplant (HSCT). Since these stem cells give rise to redblood cells, such a transplant could potentially restore her health. Whilethis might seem like an easy decision, it is not. Advanced cases havea high risk (almost 30 percent) for transplantation-related death. At thispoint, the woman is faced with a difficult and…

Explain this to me…..

Explain Maternal effect mutants affecting AP axis patterning

A defective gene on chromosome 15 causes Tay-Sachs disease. It is a central nervous system neurodegenerative disease that most often affects infants, though older children and adults can have late-onset forms of the disease. The defective gene prevents the body from making a protein called hexosaminidase A. Without, hexosaminidase A, chemicals called gangliosides build up in the nerve cells of the brain, destroying brain cells. If individuals II-1 and II-2 have another child, what is the probability they will have a child affected by Tay-Sachs? Select one: a. 0.00 b. 0.25 c. 0.50 d. 1.00