Chapter 19 Vocabulary
mcourtney 27 Jan 2008 22:49
- Activator
- A protein that binds to DNA and stimulates transcription of a specific 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.
- Cell Differentiation
- The structural and functional divergence of cells as they become specialized during a multicellular organism’s development; dependent on the control of gene expression.
- Chromatin
- The complex of DNA and proteins that makes up a eukaryotic chromosome. When the cell is not dividing, chromatin exists as a mass of very long, thin fibers that are not visible with a light microscope.
- Control Element
- A segment of noncoding DNA that helps regulate transcription of a gene by binding proteins called transcription factors.
- Differential Gene Expression
- The expression of different sets of genes by cells with the same genome.
- Enhancer
- A DNA segment containing multiple control elements that may be located far away from the gene it regulates.
- Epigenetic Inheritance
- Inheritance of traits transmitted by mechanisms not directly involving the nucleotide sequence.
- Euchromatin
- The more open, unraveled form of eukaryotic chromatin that is available for transcription.
- Genomic Imprinting
- Phenomenon in which expression of an allele in offspring depends on whether the allele is inherited from the male or female parent.
- Heterochromatin
- Nontranscribed eukaryotic chromatin that is so highly compacted that it is visible with a light microscope during interphase.
- Histone
- A small protein with a high proportion of positively charged amino acids that binds to the negatively charged DNA and plays a key role in its chromatin structure.
- Histone Acetylation
- The attachment of acetyl groups to certain amino acids of histone proteins.
- Micro-RNA (miRNA)
- A small, single-stranded RNA molecule that binds to a complementary sequence in mRNA molecules and directs associated proteins to degrade or prevent translation of the target mRNA.
- Multigene Family
- A collection of genes with similar or identical sequences, presumably of common origin.
- Nucleosome
- The basic, bead-like 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, a gene that 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 that requires some alteration to become an oncogene.
- Pseudogene
- A DNA segment very similar to a real gene but which does not yield a functional product; a gene that has become inactivated in a particular species because of mutation.
- Ras Gene
- A gene that 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.
- Repressor
- A protein that suppresses the transcription of a gene.
- Retrotransposon
- A transposable element that moves within a genome by means of an RNA intermediate, a transcript of the retrotransposon DNA.
- RNA Interference (RNAi)
- A technique to silence the expression of selected genes in nonmammalian organisms. The method uses synthetic double-stranded RNA molecules matching the sequence of a particular gene to trigger the breakdown of the gene’s messenger RNA.
- Transcription Factor
- A regulatory protein that binds to DNA and stimulates transcription of specific genes.
- Transposon
- A transposable genetic element that moves within a genome by means of a DNA intermediate.
- Tumor-Suppressor Gene
- A gene whose protein products inhibit cell division, thereby preventing uncontrolled cell growth (cancer).