Sympathetic nerves cause peristaltic contractions of reproductive ducts and accessory glands. the smooth muscle sphincter at the base of the bladder reflexively closes. semen moves into the urethra (some may seep out). what stage of the male reproductive physiology is this?

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.