Which of the following statements is true? 1.Plant cells have cell walls instead of cell membranes.
2.The excretory and the lymph system work together to control all bodily functions.
3.Reproduction by mitosis produces a single identical cell.
4.The cardiovascular system transports oxygen and carbon dioxide for the respiratory system.

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.