The hemoglobin of sickle cell anemia: 1. is oxygen rich
2. can carry less oxygen and more carbon dioxide
3. is normal
4. differs from the normal protein by one amino acid

when atoms of different types of elements join together, they make molecules called compounds. water consists of compound molecules made up of 2 hydrogen atoms and 1 oxygen atom. this is why it's called h2o. water will always have 2 times the number of hydrogen atoms as oxygen atoms.

what school and grade?

as in mitosis, dna replication occurs during interphase.   in meiosis, it occurs specifically in s phase of interphase 1.