U Flashcards
Ubiquitin
A small protein that is added to damaged proteins to mark them for degradation by the proteasome.
Ultimate Cause
see also proximate cause
Why an organism has a particular structure, function, or behavior; usually involves understanding the evolutionary advantage of the trait.
Ultrafiltration
Process of filtration of a fluid through a size-selective membrane under pressure; used to form the primary filtrate of the vertebrate kidney. Also causes the formation of lymph from blood in vertebrates.
Ultraviolet Light
Short-wavelength light (< ~300 nm); its high energy can damage macromolecules.
Uncoupling (of Oxidative Phosphorylation)
When mitochondrial respiration continues without the production of ATP.
Uncoupling Protein (UCP)
A class of proteins, which includes thermogenin (UCP1), that act by dissipating the mitochondrial proton motive force.
Unidirectional Ventilation
A type of ventilation in which the inhaled medium enters the ventilatory system by one route and exits via a different route.
Unipolar Neuron
A neuron with one process leading from the cell body; this process generally splits into two branches, one conveying information toward the cell body and one conveying information away from the cell body.
Uniporter
A class of transporter that carries a single entity (ion, atom, molecule) with each transfer.
Unitary Displacement
The distance a single motor protein moves during a cross-bridge cycle.
Unsaturated Fatty Acid
A fatty acid with one or more double bonds.
Upper Critical Temperature (UCT)
The highest temperature at which a homeothermic animal can live for extended periods; the upper limit of the thermoneutral zone.
Up-Regulation
see also downregulation
Increase in protein number or activity in a target cell.
Urea
A nitrogenous waste possessing two nitrogen atoms per molecule.
Ureotele
An animal with an excretory strategy in which urea dominates the nitrogenous wastes.
