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| Alpha carbon
alpha carbon refers to the first carbon after the carbon that attaches to the functional group. Carbon is a chemical element; its symbol is C. The carbon nucleus has six protons and six or more neutrons; six electrons are in orbit around the carbon nucleus. Carbon forms the basis for all living tissue. Alpha helix A spiral shape constituting one form of the secondary structure of proteins, arising from a specific hydrogen-bonding structure. amino acid An organic molecule possessing both carboxyl and amino groups. Amino acids serve as the monomers of proteins. amino group A functional group that consists of a nitrogen atom bonded to two hydrogen atoms; can act as a base in solution, accepting a hydrogen ion and acquiring a charge of +1. amyloid A hard waxy deposit consisting of protein and polysaccharides that results from the degeneration of tissue. astrocytosis The spread of astrocytes, a type of neuroglial cell in the central nervous system that helps support other nerve cells, into damaged tissue. ataxia Lack of coordination of the voluntary muscles resulting in irregular movements of the body. Ataxia can be brought on by an injury, infection, or degenerative disease of the central nervous system, e.g., syphilis, encephalitis, brain tumor, or multiple sclerosis. autosomal dominant gene A single, abnormal gene on one of the autosomal chromosomes (one of the first 22 "non-sex" chromosomes) from either parent can cause certain diseases. One of the parents will usually have the disease (since it is dominant) in this mode of inheritance. Only one parent must have an abnormal gene in order for the child to inherit the disease. beta pleated sheet One form of the secondary structure of proteins in which the polypeptide chain folds back and forth, or where two regions of the chain lie parallel to each other and are held together by hydrogen bonds. Bovine Spongiform Encephalopathy (BSE) Also called mad cow disease; a lethal disease that originates in cows and can spread to humans through consumption of affected neural tissue. It is called Jakob-Creutzfeldt disease in humans. It causes the brain to deteriorate through the instrument of an infectious protein called a prion. carboxyl group A functional group present in organic acids and consisting of a single carbon atom double-bonded to an oxygen atom and also bonded to a hydroxyl group. chromosome A threadlike, gene-carrying structure found in the nucleus of a cell. Each chromosome consists of one very long DNA molecule and associated proteins. Chronic Wasting Disease (CWD) A transmissible spongiform encephalopathy (TSE) of deer and American elk (wapiti). TSEs are caused by unusual infectious agents known as prions. To date, CWD has been found only in cervids (members of the deer family). First recognized as a clinical "wasting" syndrome in 1967 in mule deer in a wildlife research facility in northern Colorado, it was identified as a TSE in 1978. CWD is typified by chronic weight loss leading to death. There is no known relationship between CWD and any other TSE of animals or people. covalent bond A type of strong chemical bond in which two atoms share one pair of valence electrons. Creutzfeldt-Jakob disease (CJD) A rapidly progressive disease causing damage to the brain. It is one of a group of rare diseases that affects humans and animals, known as transmissible spongiform encephalopathies (TSE) and is believed to be caused by a prion, a type of disease-causing agent. Creutzfeldt-Jakob disease is characterized by dementia and walking difficulties. Death can occur up to two years after the first symptoms; however, most people die within seven months. There is no treatment or cure. Cysteine An amino acid, C3H7O2NS, derived from cystine and found in most proteins. depression A psychiatric disorder characterized by an inability to concentrate, insomnia, loss of appetite, anhedonia, feelings of extreme sadness, guilt, helplessness and hopelessness, and thoughts of death. disulfide bridge Strong covalent bonds formed when the sulfur of one cysteine monomer bonds to the sulfur of another cysteine monomer. encephalopathy Any disease in which the functioning of the brain is affected enzyme A protein serving as a catalyst, a chemical agent that changes the rate of a reaction without being consumed by the reaction. Fatal familial insomnia (FFI) A very rare, autosomal dominant inherited, disease of the brain. It is caused by a mutation in a protein called prion protein (PrP). The age of onset is variable ranging from 30 to 60. Death usually occurs within 3 years of onset. Feline spongiform encephalopathy A disease that affects felines. It is caused by proteins called prions. gene A discrete unit of hereditary information consisting of a specific nucleotide sequence in DNA (or RNA, in some viruses). Gerstmann-Sträussler-Scheinker syndrome (GSS) A very rare, usually familial, fatal neurodegenerative disease that affects patients in the third to seventh decades of life. It is one of the few diseases which are caused by prions; a class of diseases called transmissible spongiform encephalopathies (TSEs). People suffering from GSS initially develop ataxia (problems with movement and balance), followed later by dementia. There is no cure or treatment for GSS and patients rarely survive longer than five years. hydrogen atom The lightest chemical element; its symbol is H. Hydrogen normally consists of a single electron in orbit around a nucleus made up of a single proton. It is usually found as a gas and has several uses as a fuel. hydrogen bond A type of weak chemical bond formed when the slightly positive hydrogen atom of a polar covalent bond in one molecule is attracted to the slightly negative atom of a polar covalent bond in another molecule. hydrophobic interaction A type of weak chemical bond formed when molecules that do not mix with water coalesce to exclude the water. hydroxyl group A functional group consisting of a hydrogen atom joined to an oxygen atom by a polar covalent bond. Molecules possessing this group are soluble in water and are called alcohols. insomnia Chronic inability to fall asleep or remain asleep for an adequate length of time. ionic bond A chemical bond resulting from the attraction between oppositely charged ions. Iatrogenic A form of Transmissible spongiform encephalopathy (TSE), specifically Creutzfeldt-Jakob Disease (CJD), that is transmitted by contamination through brain surgery, corneal transplant, dura matter graft, and human growth hormone. Kuru A rare and fatal brain disorder that occurred at epidemic levels during the 1950s-60s among the Fore people in the highlands of New Guinea. The disease was the result of the practice of ritualistic cannibalism among the Fore, in which relatives prepared and consumed the tissues (including brain) of deceased family members. Brain tissue from individuals with kuru was highly infectious, and the disease was transmitted either through eating or by contact with open sores or wounds. Government discouragement of the practice of cannibalism led to a continuing decline in the disease, which has now mostly disappeared. Kuru belongs to a class of infectious diseases called transmissible spongiform encephalopathies (TSEs), also known as prion diseases. macromolecule A giant molecule formed by the joining of smaller molecules, usually by a condensation reaction. Polysaccharides, proteins, and nucleic acids are macromolecules. myoclonus A sudden shocklike twitching of muscles or parts of muscles without any rhythm or pattern, occurring in various brain disorders. Neurodegenerative disease A condition which affects brain function. Neurodegenerative diseases result from deterioration of neurons. They are divided into two groups: 1. conditions causing problems with movements 2. conditions affecting memory and conditions related to dementia neuron The characteristic specialized cell that is part of the nervous system, serving to conduct electrical impulses to and from the brain, and also between other parts of the body, and composed of a main cell body, the axon, with a varying number of processes of varying length, the dendrites; a nerve cell. The movement and behavior of higher animals depends on the signals transmitted by such nerve cells. peptide bond The covalent bond between two amino acid units, formed by a dehydration reaction. polymer A long molecule consisting of many similar or identical monomers linked together. polypeptide A polymer (chain) of many amino acids linked together by peptide bonds. polysaccharide A polymer of up to over a thousand simple sugars called monosaccharides. primary structure The level of protein structure referring to the specific sequence of amino acids. prion An infectious form of protein that may increase in number by converting related proteins to more prions. protease Any enzyme that catalyzes (or induces) the splitting of proteins into smaller peptide fractions and amino acids by a process known as proteolysis. protein A three-dimensional biological polymer constructed from a set of 20 different monomers called amino acids. PRNP gene Provides instructions for making a protein called the prion protein (PrP), which is active in the brain and several other tissues. PrP A prion-related protein PrPc The cellular form of a prion-related protein PrPsc The pathogenic form of a prion-related protein. The "Sc" superscript was initially derived from the term scrapie because scrapie is the prototypic prion disease. Since all of the known prion diseases of mammals involve aberrant metabolism of PrP similar to that observed in scrapie, use of the "Sc" superscript is suggested for all abnormal, pathogenic PrP isoforms. quaternary structure The particular shape of a complex, aggregate protein, defined by the characteristic three-dimensional arrangement of its constituent subunits, each a polypeptide. Scrapie A fatal, degenerative disease that affects the nervous systems of sheep and goats. It is one of several transmissible spongiform encephalopathies (TSEs), which are related to bovine spongiform encephalopathy (BSE or "mad cow disease"). Like other spongiform encephalopathies, scrapie is believed to be caused by a prion. Scrapie has been known since the 18th century (1732) and does not appear to be transmissible to humans. secondary structure The localized, repetitive coiling or folding of the polypeptide backbone of a protein due to hydrogen bond formation between peptide linkages. serine An amino acid, CH2OHCH(NH2)COOH, that is a common constituent of many proteins. Sexually Transmitted Disease Any of various diseases, including chancroid, chlamydia, gonorrhea, and syphilis, that are usually contracted through sexual intercourse or other intimate sexual contact. spongiform change Brain damage characterized by a spongy appearance of brain tissue seen under a microscope tertiary structure Irregular contortions of a protein molecule due to interactions of side chains involved in hydrophobic interactions, ionic bonds, hydrogen bonds, and disulfide bridges. Transmissible mink encephalopathy A medical condition believed to be caused by proteins called prions. Transmissible spongiform encephalopathies (TSEs) Also known as prion diseases; a group of rare degenerative brain disorders characterized by tiny holes that give the brain a "spongy" appearance. These holes can be seen when brain tissue is viewed under a microscope. Ungulate spongiform encephalopathy A disease that affects hoofed mammals such as horses, cattle, deer, swine, and elephants. It is caused by proteins called prions. valine An essential amino acid, C5H11NO2. variant A form of Transmissible spongiform encephalopathy (TSE), specifically Creutzfeldt-Jakob Disease (CJD), that is transmitted by consuming cattle infected with Bovine Spongiform Encephalopathy (BSE). x-ray crystallography A technique that depends on the diffraction of an X-ray beam by the individual atoms of a molecule to study the three-dimensional structure of a molecule. |
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