What is the cause of sickle cell anemia?
question 5 options:
a change in one amino acid in the polypeptide chain which changes the shape of the red blood cell
mosquitos
a change in the sequence of amino acids in hemoglobin which causes few red blood cells to be made
a change in one amino acid in the protein chain which causes hemoglobin to not be able to carry oxygen correctly

bacteria could be both, harmful and to us. harmful bacteria could make us sick and probably even by getting the chances of getting a disease, but good bacteria fight it off with your immune system. there is always bacteria everywhere we go. we need to make sure to wash our hands after using the restroom, before eating, after eating, after petting an animal too. so you see, bacteria is everywhere and is harmful or . i hope this . : ) : ) : )