Sickle-cell anemia is a genetic blood disorder. Red blood cells normally have a round shape and pass easily through small blood vessels as they deliver oxygen to the tissue. But in people with sickle-cell anemia, some red blood cells are shaped like a sickle, or a "C." The red blood cells with this sickle shape do not live as long as healthy, round blood cells. The sickling of red blood cells is thought to be due to problems with the hemoglobin gene. The unusual behavior of the hemoglobin causes rigid fibers of protein to form in the cell membrane, leading to a decrease in its flexibility and the change in cell shape. These rigid, deformed cells are more likely to rupture or get stuck in small blood vessels, creating a blockage. When blood flow to tissues is interrupted, this can lead to long-term damage to organs and even cause death.
1. a) Based on the information above, what are at least two changes that take place in the red blood cells of individuals with sickle-cell anemia? (2 points)

b) Describe two ways sickled cells can affect an individual with this condition. (2 points)
c) Does the description of sickled blood cells in the passage match the photograph above? (2 points)

2. Find a scientific article about sickle-cell anemia (also called sickle-cell disease). Two examples are "Learning About Sickle Cell Disease" from the National Human Genome Research Institute (www. genome. gov/10001219) and "What Is Sickle Cell Anemia?" from the National Heart, Lung, and Blood Institute (www. nhlbi. nih. gov/health/health-topics/topics/sca /).
After reading the article, write a paragraph that summarizes what you learned. Include what you found out about heredity. (7 points)
3. Malaria is a disease caused by parasitic microorganisms that invade healthy red blood cells. The microorganisms are transmitted from person to person by mosquitoes. People who produce only normal red cells are good hosts for the parasites and easily get the disease, which often results in death. However, these microorganisms are unable to thrive in people who carry either one or two sickle cell alleles.
The diagram below shows the possible outcomes for the children of parents who each carry one sickle-cell allele. R represents the allele for normal blood, and r represents the allele that leads to sickle-cell anemia.

a) Based on the inheritance patterns above and assuming the presence of malaria-causing microorganisms and mosquitoes, what percentage of the children in the diagram would be expected to live long lives without special medical care? (2 points)

b) Describe one advantage of carrying only one sickle-cell allele. (1 point) c) Describe one disadvantage of carrying only one sickle-cell allele. (1 point)
4. Red blood cells usually live for about 120 days before they die and need to be replaced. Sickle cells are fragile — their membranes break apart easily, causing the cells to die after only 10 to 20 days. The result in those with sickle-cell disease is a chronic shortage of red blood cells known as anemia.
Based on this information, why do people with anemia become easily fatigued? (3 points)

NO MESSING AROUND THIS COUNT AS 63% OF MY GRADE