Glossary - T |
A | B | C | D | E | F | G | H | I | J | K | L | M
N | O | P | Q | R | S | T | U | V | W | X | Y | Z |
| |
| |
Telomere
| What it's not: |
Franglish for “I’m gonna tell your Mom!” |
| What it is: |
Human chromosomes are linear. Believe it or not, this can create some problems for the cell because it wants to fix broken ends of free-floating double-stranded DNA. Also, when the DNA strand replicates, it depends on a template that sticks to the upcoming sequence. But when you reach the end, there is nothing to stick to; therefore, the ends get shorter with each replication. To distinguish the ends of our chromosomes, we have caps on them- short tandem repeats of (TTAGGG)n which form a closed loop, protecting the chromosome end. |
Teratogens
| What it's not: |
18-sided dice used in specialty Dungeons & Dragons games
|
| What it is: |
A teratogen is a substance or exposure that causes (or increases the risk for) birth defects in a developing baby. Drugs, infections, chemicals, radiation are all examples of substances that have the potential to cause harm to a developing baby. One of the better known teratogens is thalidomide, which was a drug given to pregnant women in the mid-1900s to help ease morning sickness. It was eventually realized that thalidomide can cause birth defects like short or missing arms and legs in a developing baby if used early in pregnancy.
|
Trait
| What it's not: |
An Aussie term for 'treat'
|
| What it is: |
A trait is a characteristic that an individual possesses. It could be a personality or behaviour trait (like being warm and friendly), intelligence (a high IQ score) or a physical feature (like red hair or height). Genes may play an important role in a trait or the trait may be influenced very little by genes and caused mostly by environmental factors.
|
Transcript RNA (tRNA)
| What it's not: |
The summary of a day’s court cases typed up by the court reporter.
|
| What it is: |
During translation when mRNA is read to make proteins, the transfer RNA works with the ribosomes to bring amnio acids into place along the mRNA template. Each type of tRNA molecule binds only to a specific type of amnio acid.
|
Transcription
| What it's not: |
The process of making emails impossible to read by instantly translating them into ancient dead languages. |
| What it is: |
In general, transcription is copying from one medium to another, like transcribing speech into phonetic symbols for example. RNA transcription is the enzymatic process where complementary RNA sequences are created from DNA templates. |
Transgenic
| What it's not: |
Some men’s desire to wear dresses |
| What it is: |
When organism has had a gene from another organism (even a different species) inserted to it or when an organism’s DNA is artificially modified in some way, said organism is labeled ‘transgenic’.
The advantages of this technique? Take cultivated apples, for example. Today, instead of taking several decades of cross-pollinating and grafting to produce apples with desirable traits, genetic engineering can produce apples with particular insect-resisting or fruit-enhancing properties in one generation. In addition, other food crops can be vitamin-enriched, made more disease and pest resistant, and even be engineered to produce edible vaccines. Transgenic or genetically modified crops continue to raise contentious issues and spawn vitriolic arguments between opponents and proponents, in regard to real and imagined environmental, health and economic risks. For a balanced overview of the science, technology and issues attached to genetically modified organisms, see Mark L. Winston. Travels in the Genetically Modified Zone. (Cambridge, Massachusetts: Harvard University Press, 2002). |
Translation
| What it's not: |
What you get lost in. |
| What it is: |
In general, translation is taking something incomprehensible and putting it into a form that someone can understand. (Hopefully, that’s what this glossary does.) In the cell, translation is the process where nucleic acid information (coded in RNA) is turned into amino acid chains that can then be folded and made into proteins. In other words, translation is the synthesis of proteins from an mRNA template. |
Translocation
| What it's not: |
One of the top 10 songs of 2008:Everybody’s doing a brand new dance now
Come on, baby, do the trans-location
I know you’ll get to like it if you give it a chance now
Come on, baby, do the trans-location
|
| What it is: |
A chromosome translocation is when part of a chromosome is transferred onto another chromosome. Translocations may be balanced (having the right amount of chromosome material) or unbalanced (having too much or too little chromosome material). A reciprocal translocation is where a piece of one chromosome is exchanged for the piece of another chromosome. Another form of translocation is the Robertsonian translocation where two acrocentric chromosomes stick together. Acrocentric chromosomes have their centromere at one end and are chromosomes 13, 14, 15, 21, and 22.
|
Transposon
| What it's not: |
A person who makes a new life in a new country. |
| What it is: |
A
genetic element that contains the material necessary to move the said
element from one site in the genome to another site in the same genome,
or to a site in a different one. In bacteria, some transposons include
additional genes in the form of antibiotic resistance elements. An
ancient virus can even make a new life in a different spot in a genome.
This genetic proclivity is often put to use in fly transgenic
experiments (wow – doesn’t that sound sci-fi?). |
Triple Marker Screen
| What it's not: |
Baskin Robbins' newest ice cream flavour: a trio of Tiramisu, Marshmallow and Strawberry flavours together in one scoop.
|
What it is:
|
The triple marker screen is a screening test available to pregnant women in British Columbia when they are between 15 and 20 weeks of pregnancy. It involves a blood test of the mother which estimates the chance of the pregnancy being affected with one of three conditions: Down syndrome, Trisomy 18 and Neural tube defects like spina bifida. It is a way for women to obtain a more exact risk assessment of their pregnancy instead of the risk information provided by their maternal age alone. |
Triplet Repeat Expansion
| What it's not: |
The rapid growth spurt that triplet siblings undergo as they reach puberty.
|
| What it is: |
Some genetic conditions are caused when there is an increase in the size of a repeated unit within the gene. Triplet repeats are 3 nucleotides that are typically repeated a few times. A triplet repeat can become unstable and expand. If this large repeat is within a gene, it can cause disease. Huntington’s disease is one condition that shows triplet repeat expansion. The CAG triplet repeat in the Huntingtin gene is typically repeated less than 36 times but individuals who have the CAG sequence repeated over 36 times will be affected with Huntington’s disease.
|
Trisomy
| What it's not: |
A felony under the criminal code
|
| What it is: |
The term trisomy is used to describe when there is an extra chromosome (or piece of chromosome). People typically have two copies (disomy) of all of their chromosomes. A trisomy is when there are three copies of a chromosome instead of two copies. Often, having a complete chromosome trisomy is not compatible with life. One exception is Down syndrome where individuals have three copies of chromosome 21 instead of two copies. |
Tumour Suppressor
| What it's not: |
Clearasil’s newest rival in the fight to tame teenage acne.
|
| What it is: |
A tumour suppressor gene is a normal gene that controls how often and how fast a cell divides. If both copies of a tumour suppressor gene become faulty in one cell, then cell growth gets out of control and a tumour may develop. This ‘two hit hypothesis’ describes how some forms of cancer can develop from the loss of both alleles of a gene that controls cell division. It is similar to a car in motion: if the regular set of brakes fail, the parking brake may still be used to stop the car and vice versa. But if both sets of breaks fail, the car may crash. If both copies of a tumour suppressor gene are inactivated, the growth of the cell may go out of control and become a tumour.
|
|
|
|
|
