Biology U
What is ubiquitous ?
Existing or having presence everywhere at the same time. For example, ribonuclease, an enzyme that degrades RNA, is ubiquitous in living organisms.
What is ultimate causation ?
An explanation for why a behavior has evolved and its context within the environment. Identifies the evolutionary factors responsible for the behavior and its purpose within a biological system.
What is ultrasound ?
The use of sound with a frequency higher than 20,000 Hz. Used to obtain images for medical diagnostic purposes, especially during pregnancy.
What is umwelt ?
The total sensory and perceptual world of an animal.
What is uniformitarianism ?
A doctrine that states that current geological and biological processes, occurring at the same rates and in the same manner observed today, account for all of Earth’s geological and biological features. “The present is the key to the past.” The doctrine of uniformitarianism was advanced by James Hutton (1726–97) in his publication, Theory of the Earth (1785).
What is unsaturated fatty acids ?
Fatty acids are the essential building blocks of all fats in our food supply and body, but not all of them have beneficial results. There are five major fatty acids types: saturated (SAFA), unsaturated (UFA), monounsaturated (MUFA), polyunsaturated (PUFA), and essential (EFA).
An unsaturated fatty acid is a long-chain carboxylic acid that contains one or more carbon C=C double bonds. They occur when all of the carbons in a chemical chain are not saturated with hydrogen, so that the fat molecule contains one or more double bonds and produces a fat that is fluid at room temperature.
The double bonds in a molecule of an unsaturated fatty acid can be found in two forms known as cis and trans.
Cis double bonds produce a kink, or a bend of about 30 degrees for each double bond into the backbone and can flip over to the trans form under high temperatures. Trans double bonds allow the molecule to lie in a straight line. However, the human body cannot convert the trans form into nutrients and thus cannot activate the metabolic activities required to convert to the active cis forms. This can lead to a deficiency in essential fatty acids. The more double bonds, and therefore the more kinks, the more beneficial it is to human health. The kinks, by completely changing the physical and chemical properties, allow it to form essential protein associations more easily, disperse more saturated fatty acids, and interact with water or blood.
What is urea ?
A nitrogen-containing waste product; a result of the normal breakdown of protein in the liver in mammals. It is created in liver cells from ammonia and carbon dioxide, and carried via the bloodstream to the kidneys, where it is excreted in the urine along with nitrogen. Urea accumulates in the body of people with renal failure. Urea is also a synthetic source of nitrogen made from natural gas.
What is urease ?
A nickel ENZYME, urea amidohydrolase, that catalyzes the HYDROLYSIS of urea to ammonia and carbon dioxide. The ACTIVE SITE comprises two Ni(II) ions bridged by a carbamate.
What is ureter ?
Tubes, about eight to 12 inches in length, that run from the kidney to the bladder on each side and carry urine from the kidneys to the bladder.
What is urethra ?
A narrow tube or canal that carries urine from the bladder, and semen from the prostrate and other sex glands, out via the tip of the penis to the outside of the body.
What is uric acid ?
The end results of urine breakdown, a product of protein metabolism, which is the major form of excreting metabolic nitrogen out of the body. Too much uric acid in the blood and its salts in joints lead to gout, which causes pain and swelling in the joints. When urine contains too much uric acid, “kidney” or uric acid stones can develop.
What is urochordate ?
A chordate (organism having a notochord at some stage of development) without a back bone, also called a tunicate or sea squirt; a sessile marine animal composed of a sack with two siphons in which water enters and exits, filtered inside by the sack-shaped body.
What is urticating ?
The act of causing itching or burning sensation to the skin or eyes as a result of being inflicted by the entry of poison-filled spines (tips often break off) or setae that contain venom capable of causing pain and irritation. Found on the abdomen of tarantulas, some caterpillars, and the Urticaceae, plants of the nettle family.
What is uterus ?
A pear-shaped hollow female reproductive organ in the pelvis area, at the top of the vagina, where eggs are fertilized and/or development of the young occurs.
What is utricle ?
The larger of two membranous sacs (the other is the saccule) within the vestibule, the cavity at the entrance to the bony labyrinth of the inner ear. The utricle contains receptors for balance and a macula that is responsive to linear acceleration. The macula is a group of hair cells residing in either the saccule or the utricle and covered with gelatinous material containing otoliths, which are small granules of calcium carbonate. The ear’s semicircular canals lead to and from the utricle.
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