A 7-yeаr-оld girl is brоught tо the hospitаl аfter repeated episodes of extreme tiredness. She is becoming very pale, and shows signs of delayed growth. Blood tests reveal abnormally shaped red blood cells that break down very quickly. Genetic testing confirms she has sickle cell disease, caused by a mutation in the HBB gene. In this mutation one amino acid substitution in hemoglobin leads to rigid, sickle-shaped (banana shaped) red blood cells. These abnormal cells block blood flow and reduce oxygen delivery to tissues. Label your answers 1 and 2. 1. Sickle blood cells have an irregular shape and don't hold oxygen as well so these cells break down fast. After receiving signals about low oxygen, the bone marrow (where red blood cells are produced) becomes more active. Explain the steps of homeostasis (as seen in question 6 above) that may be involved and any potential downsides to the bone marrow response. 2. Why would altering a single amino acid have such a dramatic effect on the protein function?