(also, second messenger) small molecule that transmits signals within a cell

communication within cells

process of bone development from fibrous membranes

space between the layers of pleura

competition between members of the same sex for a mate

competition between members of the same species

opening section of a scientific paper, which provides background information about what was known in the field prior to the research reported in the paper

non–protein-coding intervening sequences that are spliced from mRNA during processing

(also, invertebrates) category of animals that do not possess a cranium or vertebral column

atom or chemical group that does not contain equal numbers of protons and electrons

cell-surface receptor that forms a plasma membrane channel, which opens when a ligand binds to the extracellular domain (ligand-gated channels)

chemical bond that forms between ions with opposite charges (cations and anions)

pigmented, circular muscle at the front of the eye that regulates the amount of light entering the eye

bone with complex shapes; examples include vertebrae and hip bones

chemical reaction where reactants proceed unidirectionally to form products