| A | B |
|---|
| acetylation | Attachment of an acetyl group to a compound, such as DNA. |
| apoptosis | Programmed cell death. Molecular signals activate weapons of self-destruction in body cells that finished their prescribed functions or became altered, as by infection or cancerous transformation |
| Barr body | Randomly condensed one of two X chromosomes in cells of female mammals. |
| cancer | Malignant tumor; mass of altered cells that divide abnormally. Potentially lethal |
| cell differentiation | Key development process. Cell lineages become specialized in structure, composition, and function by activating and suppressing part of the genome selectively |
| dosage compensation | Any mechanism that balances gene expression between the sexes during critical early stages of development |
| enhancer | A short DNA base sequence that is a binding site for an activator protein. |
| gene control | One of the molecular mechanisms that govern when and how fast specific genes will be transcribed and translated, and whether gene products will be activated or inactivated |
| growth factor | Protein that plays a role in the body's growth |
| hormone | Signaling molecule secreted by one cell that stimulates or inhibits activities of any cell with receptors for it. Animal hormones are picked up and transported by the bloodstream. |
| metastasis | Abnormal migration of cancer cells which may establish colonies in other tissues. |
| methylation | Attachment of a methyl group to an organic compound; a common gene control. |
| mosaic tissue effect | Patches of body tissues in which one or the other of two X chromosomes is being expressed; outcome of X chromosome inactivation in all female mammals. |
| negative control | Use of regulatory proteins to trigger a slowdown in gene expression. |
| oncogene | Any gene having the potential to induce cancerous transformation. |
| operator | Very short base sequence between a promoter and bacterial genes; a binding site for a repressor that can block transcription. |
| Operon | Promoter-operator sequence serving more than one bacterial gene; part of a control that adjusts transcription rates up or down. |
| positive control | Use of regulatory proteins to promote gene expression. |
| promoter | Short stretch of DNA to which RNA polymerase can bind and start transcription. |
| regulatory protein | Component of mechanisms that control transcription, translation, and gene products by interacting with DNA, RNA, new polypeptide chains, or proteins (e.g., enzymes) |
| repressor | Protein that binds with an operator on bacterial DNA to block transcription. |
| X chromosome inactivation | One of the two X chromosomes in somatic cells of mammalian females condenses, which inactivates most of its genes. A dosage compensation mechanism |
