Note: Some words can have differing definitions depending on the context in which they are used. The definitions presented here are the ones that best apply to the words as they are used on the HOPES site.
tagging - The marking of a target molecule; can be used in multiple contexts, for example a protein may be tagged by a cell for degradation or a drug may be tagged before administration to allow researchers to track where it travels in the body.
target site - A specific sequence of amino acids in a protein that serve as the point at which the protein interacts with other specific proteins.
tau pathologies - neurodegenerative diseases related to problems with the tau protein found in nerve cells. Tau pathologies include Alzheimer's disease and myotonic dystrophy, among others.
tauroursodeoxycholic acid (TUDCA) - An acid found in large quantities in bear bile and small amounts in human bile. It helps in preventing programmed cell death, possibly by protecting mitochondria.
telomeres - Highly repetitive DNA at the ends of a chromosome, some of which is lost during each cell replication. It is thought that this process contributes to aging; once the telomeres have been completely lost, DNA that is necessary for proper cellular functioning may begin to be lost instead.
temporal lobe - A part of the brain associated with memory, hearing, and perception.
teratogenic - A substance that disturbs the development of the embryo or fetus
tertile - Describes the distribution of scores on a test. A tertile is one-third of the total number of scores. For instance, the highest tertile is the one-third of scores that have the highest scores on the test.
testosterone - A steroid hormone produced primarily in the testes and responsible for the development and maintenance of male secondary sex characteristics. It is also produced synthetically for use in medical treatment.
Tetracycline - an antibiotic drug that is used for medicine and for research. In some cases it can serve to regulate the production of certain proteins in the cell, by starting or stopping transcription for a certain target gene
thalamus - A collection of nerve cells in the brain. Although it performs many functions, the primary role of the thalamus is to relay sensory information from other parts of the brain to the cerebral cortex.
thymine - One of the four nitrogenous bases found in DNA; pairs with the base adenine; often abbreviated as the letter "T"; see Figure B-3.
thymus gland - The thymus gland lies at the root of the neck behind the breastbone. It grows from birth to puberty and then starts to diminish in size but remains active. Its main function is the formation of T-lymphocytes which are an essential part of the immune system.
thyroid gland - A small organ located near the neck that produces several hormones.
Tibetan Buddhism - A branch of Buddhism, which traveled to Tibet from India sometime after Buddhism had traveled to eastern China from India. This resulted in some additional sophisticated techniques for understanding ultimate truth.
tolerability - The potential of a drug to be endured. A drug with good tolerability produces few side effects in the subject.
tonic-clonic - Seizures that involve both tonic and clonic phases. During the tonic phase the body is rigid, but during the clonic phase the individual often suffers from rhythmic jerking movements. When tonic-clonic seizures are generalized, they are referred to as grand mal seizures.
total functional capacity (TFC) - A standardized scale used to assess capacity to work, handle finances, perform domestic chores and self-care tasks, and live independently. The TFC scale ranges from 13 (normal) to 0 (severe disability).
totipotent - The ability to give rise to all cell types (including the placenta, other supporting tissues, and the body of the organism itself); having unlimited capability.
toxic soluble oligomers - Small, harmful molecules believed to trigger cell damage in HD and related diseases.
trachea - (a.k.a. the "windpipe") the main trunk of the system of tubes by which air passes between the mouth and the lungs.
trait - A physical characteristic brought about by the expression of a gene or many genes. Examples of traits are height, eye color, and the ability to roll your tongue. Variations in these characteristics are dependent upon the particular alleles an individual has for the genes determining the trait.
transcribe - To undergo transcription. In order for the DNA code of a gene to result in the production of a specific protein, the gene must first be transcribed.
transcriptional dysregulation - A disease mechanism that disrupts the expression of certain genes, which affects when essential proteins are produced by the cell. Transcriptional dysregulation plays a major role in HD.
transgene - A foreign piece of DNA that has been inserted into the germ line of an organism. Since germ cells give rise to the reproductive cells, an organism that contains a transgene will pass it down to all of its descendents. An organism that contains a transgene is known as "transgenic."
transgenic - An organism that has had DNA from another organism introduced into it. For example, if jellyfish DNA is introduced into a mouse, the mouse is then called a transgenic mouse. Transgenic animals are generated by introducing the outside DNA into the developing embryo and then implanting the embryo into a host mother until the animal is born.
transposable element - Segment of DNA that can move around within a chromosome or between chromosomes in the same cell. Can also be called a transposon.
trehalose - A disaccharide made out of two glucose molecules that has been shown to stabilize proteins. Trehalose is used as a sweetener and preservative, and can be found in foods such as lobster, shrimp, honey, and mushrooms.
tremor - A quivering, involuntary movement of a part or parts of the body.
triglyceride - A fat-like substance found in the blood.
trinucleotide repeat disorder - An illness in which there is an abnormally large number of repeats of a specific codon of DNA. In addition to Huntington's disease, other trinucleotide repeat disorders include fragile X syndrome and spinobulbar muscular atrophy. In HD, the repeated codon is C-A-G, which codes for the amino acid glutamine.
triplet repeat - A three letter sequence of bases (codon) that is repeated consecutively in a section of DNA. In HD, the repeated sequence is C-A-G. Also referred to as a trinucleotide repeat or a codon repeat.
An educational product of HOPES, not to be used in place of medical care. For more information about HOPES, click on the Logo.
To contact HOPES with comments or questions, click here.
