What is the movement of molecules across a barrier such as the semi-permeable cell membrane called

How can scientists test their ideas about the origin of the universe if they can't physically interact with or study?

Which part of the cell is affected by the movement of molecules through diffusion, osmosis and active transport?

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.