An allele that does not express its phenotype in the presence of a dominant allele.

New gene combinations achieved by sexual reproduction or crossing over in eukaryotes, and by transformation, transduction, or conjugation in prokaryotes.

The process whereby an atom, ion, or molecule gains electrons or hydrogens; the loss of oxygen from an atom, ion, or molecule.

An involutary nervous pathway consisting of sensory neurons, interneurons, motor neurons, and effectors; it occurs in response to a specific stimulus.

The period in time following an action potential, during which the neuron is incapable of depolarization.

The natural renewal of a structure, as of a lost tissue or part.

Hormones elaborated in one structure that cause the release of hormones from another structure; applied to substances of established chemical identity, while those whose chemical structure is unknown are called releasing factors.

Of or pertaining to the kidneys.

In genetics, a substance produced by a regulator gene that acts to prevent initiation by the operator gene of protein synthesis by the operon.

In cellular respiration: the exergonic metabolic processes in living cells by which molecular oxygen is taken in, organic substances are oxidized, free energy is released, and carbon dioxide, water, and other oxidized products are given off by the cell. Or the exchange of oxygen and carbon dioxide between the atmosphere and the body cells, including ventilation (inhalation and exhalation); diffusion of oxygen from alveoli to blood and of carbon dioxide from blood to alveoli; and transport of oxygen to and carbon dioxide from body cells.

The potential difference across the membrane of a normal cell at rest.

The delicate multilayered light-sensitive membrane lining the inner posterior chamber of the eyeball containing the rods and cones and connected by the optic nerve to the brain.