In the early 1930’s william rose fed laboratory rats a mixture of all 19 amino acids known to be present in proteins. he observed that his rats lost weight. this observation led to the discovery of as the 20th amino acid found in proteins.

The blue particles in this image are able to cross the cell membrane through simple diffusion. how will they be transported? outside the cell inside the cell o a. the substances will move directly across the membrane from outside the cell to inside the cell. b. the substances will move through channels in the membrane proteins from outside the cell to inside the cell. o c. the substances will move through channels in the membrane proteins from inside the cell to outside the cell. o d. the substances will move directly across the membrane from inside the cell to outside the cell.