Chapter 19 Key Terms and Roots
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EricaSeifert on December 12, 2008
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32 terms
Terms | Definitions |
|---|---|
 activator | A transcription factor that binds to an enhancer and stimulates transcription of a gene. |
| alternative RNA splicing | A type of regulation at the RNA-processing level in which different mRNA molecules are produced from the same primary transcript depending on which RNA segments are treated as exons and which as introns. |
| control elements | Segments of noncoding DNA that help regulate transcription of a gene by binding proteins called transcription factors. |
| DNA methylation | The addition of methyl groups (—CH3) to bases of DNA after DNA synthesis; may serve as a long-term control of gene expression. |
| DNA-binding domain | A part of the three-dimensional structure of a transcription factor that binds to DNA. |
| enhancer | A DNA sequence that recognizes certain transcription factors that can stimulate transcription of nearby genes. |
| euchromatin ("true chromatin") | The more open, unraveled form of eukaryotic chromatin that is available for transcription. |
| gene amplification | The selective synthesis of DNA, which results in multiple copies of a single gene, thereby enhancing expression. |
| genomic imprinting | The parental effect on gene expression whereby identical alleles have different effects on offspring, depending on whether they arrive in the zygote via the ovum or via the sperm. |
| heterochromatin | Nontranscribed eukaryotic chromatin that is so highly compacted that it is visible with a light microscope during interphase. |
| histone acetylation | The attachment of acetyl groups to certain amino acids of histone proteins. |
| immunoglobulin (lg) | One of the class of proteins comprising the antibodies. |
| multigene family | A collection of genes with similar or identical sequences, presumably of common origin. |
| nucleosome | The basic, beadlike unit of DNA packaging in eukaryotes, consisting of a segment of DNA wound around a protein core composed of two copies of each of four types of histone. |
| oncogene | A gene found in viruses or as part of the normal genome that is involved in triggering cancerous characteristics. |
| p53 gene | The "guardian angel of the genome," p53 is expressed when a cell's DNA is damaged. Its product, p53 protein, functions as a transcription factor for several genes. |
| proteasome | A giant protein complex that recognizes and destroys proteins tagged for elimination by the small protein ubiquitin. |
| proto-oncogene | A normal cellular gene corresponding to an oncogene; a gene with a potential to cause cancer but which requires some alteration to become an oncogene. |
| pseudogenes | DNA segments very similar to real genes but which do not yield functional products. |
| ras gene | This gene codes for Ras protein, a G protein that relays a growth signal from a growth-factor receptor on the plasma membrane to a cascade of protein kinases that ultimately results in the stimulation of the cell cycle. Many ras oncogenes have a point mutation that leads to a hyperactive version of the Ras protein that can lead to excessive cell division. |
| repetitive dna | Nucleotide sequences, usually noncoding, that are present in many copies in a eukaryotic genome. The repeated units may be short and arranged tandemly (in series) or long and dispersed in the genome. |
| retrotransposons | Transposable elements that move within a genome by means of an RNA intermediate, a transcript of the retrotransposon DNA. |
| tumor-suppressor gene | A gene whose protein products inhibit cell division, thereby preventing uncontrolled cell growth (cancer). |
| eu- | true |
| hetero- | different |
| immuno- | safe, free |
| nucleo- | nucleus |
| -soma | body |
| proto- | first |
| onco- | tumor |
| pseudo- | false |
| retro- | backward |
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