Identify how the physical barriers of the immune
system protect the body against pathogens.
Check all that apply.
•your nose produces oil to keep pathogens
from entering the body through your nose
•skin contains tightly packed cells
•skin is tough, flexible, and waterproof
•your cough when a pathogen enters your
mouth
•you sneeze when a pathogen enters your
nose

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.