The predominant cells in blood are the red blood cells (RBC) which contains a protein called hemoglobin. Hemoglobin is the principal determinant of the color of blood. Arterial blood and capillary blood are bright red, as oxygen imparts a strong red color to the heme group.
Concept 21 RNA is an intermediary between DNA and protein. DNA is found mostly in the cell nucleus, but another type of nucleic acid, RNA, is common in the cytoplasm. Watson and Crick proposed that RNA must copy the DNA message in the nucleus and carry it out to the cytoplasm, where proteins are synthesized. Crick also predicted the existence of an adaptor molecule that reads the genetic code and selects the appropriate amino acids to add to a growing polypeptide chain.
1 RNA is found in both the nucleus and the cytoplasm. 2  RNA concentration correlates with protein production. 3  Cells that produce large amounts of protein have cytoplasmic dye-and radiation-absorbing regions indicative of the presence of nucleic acids.he single-celled alga Acetabularia played an important role in elucidating the site of protein synthesis. During part of its life cycle, Acetabularia takes on an unusual umbrella-like form, during which the cell 's nucleus is located completely within the boundaries of a spatially distinct foot called a rhizoid.