3. Sickle cell anemia is caused by a genetic defect in coding for the amino acid sequence of hemoglobin, causing abnormal red blood cells. The blood of heterozygous persons appear normal, but when it is held under low oxygen concentration, the red blood cells become sickle shaped. A young man has a sister who died of sickle cell, and he is concerned about the possibility of the condition appearing in his children. When his blood is placed under low oxygen concentration the cells become sickled, but those of his wife do not. What is the probability of their children having the disease? How many of their children are likely to be carriers?

Which term best describes a community in which people work mostly in factories? a.agricultural. b.hunting and gathering. c.domesticated. industrial.

The tasmanian devil, a marsupial carnivore, is facing extinction due to devil facial tumor disease (dftd) which causes bulging cancerous lumps and lesions to erupt around the face and neck — often causing enough deformation to make seeing or eating difficult. dftd has evolved into a contagious cancer, a trait that is unique among cancers. devil mating behavior involves biting around the head and neck, allowing cells from one individual — especially cells from the crumbly dftd tumors — to be transferred to the wounds or face of a new individual. this marsupial was once found across australia, but sea levels rose, isolating the tasmanian population, while the australian population went extinct. what would be an outcome of genetic isolation that is likely to have impacted the spread of dftd? a) reduced territory puts diseased individuals in greater contact with non-diseased ones. b) inbreeding results in less variation in facial features so the cancer is generally fatal. c) genetic isolation has made it difficult for scientists to develop a vaccine against dftd. d) the lack of genetic variation in the immune system of tasmanian devils minimizes resistance to the disease.

One function of the poly-a tail on eukaryotic mrna sequences is to the mrna be transported from the nucleus to the cytoplasm. prokaryotic mrna also has a poly-a tail. choose the best explanation of the prokaryotic poly-a tail. a. prokaryotic poly-a tails are composed of a different molecular structure compared with eukaryotic poly-a tails. b. prokaryotic poly-a tails have the same functions as eukaryotic poly-a tails, because this process is highly conserved throughout different species. c. prokaryotic poly-a tails aren't important, because prokaryotes don't have nuclei. d. prokaryotic poly-a tails have other functions,because prokaryotes don't have nuclei.