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.
Ureter
The tube connecting the kidney to the bladder.
Urethra
The tube carrying urine from the urinary bladder to the excretory opening.
Uric Acid
A nitrogenous waste possessing four nitrogen atoms per molecule.
Uricolytic Pathway
A pathway of breakdown of uric acid present in all animals.
Uricotele
An animal with an excretory strategy in which uric acid is the dominant nitrogenous waste.
Urine
A solution of nitrogenous waste produced by the kidney or kidneylike tissues.
Utricle
A part of the vertebrate inner ear.
