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Enzyme
| What it's not: |
Car wax. |
| What it is: |
Enzymes are catalysts, substances that can speed up chemical reactions without getting chemically changed themselves. Human saliva contains an enzyme called amylase that speeds up the chemical reaction of converting starches in our food to sugars |
Epistasis
| What it's not: |
The last name of a famous Greek soccer player known for his tendency to ‘run out of gas’. |
| What it is: |
Epistasis describes an interaction between two genes that gives a different phenotype compared to when these genes act independently. A gene is epistatic when it changes the effect of another gene. Epistatic genes can also be called ‘inhibiting genes’. For instance, a mutation that causes complete baldness would be epistatic to a gene that caused hair to be purple. (You can’t have purple hair if you are bald!) |
Exon
| What it's not: |
A Greek expression, loosely translated as “Hit the road, Xerxes”; an oil company. |
| What it is: |
A sequence of bases in a stretch of DNA that codes for a specific protein. The word ‘exon’ breaks down into ‘ex’ for ‘expressed’ on ‘on’ for a ‘basic unit’. In humans, exons aren’t arranged side by side. They’re separated by introns. The portions of DNA found in mature RNA after splicing, exons can be read or expressed in different combinations, leading to different final proteins. |
Expressivity
| What it's not: |
A personality trait found in extroverts |
| What it is: |
The variability in the expression of the severity/manifestation of a trait or disease from the same genotype. If a trait has 'variable expressivity', one person can have obvious or severe symptoms whereas another is mildly affected. For example, the symptoms of Neurofibromatosis can vary significantly between patients - even identical (monozygotic) twins have had some different clinical manifestations. |
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