Multicellular organisms are made up of different types of differentiated cells. Given that all cells in an organism
have the same DNA-and thus the same genes-explain how it is that different genes can be expressed only in
certain types of cells.

You have just sequenced a new protein found in mice and observe that sulfur-containing cysteine residues occur at regular intervals. what is the significance of this finding? it will be important to include cysteine in the diet of the mice. cysteine residues are required for the formation of α helices and β pleated sheets. cysteine residues are involved in disulfide bridges that form tertiary structure. cysteine causes bends, or angles, to occur in the tertiary structure of proteins.