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CH18 Regulation of Gene Expression - Vocab
Vocabulary from Chapter 18 of Campbell Biology (9th ed.)
38
Biology
Undergraduate 2
03/07/2011

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Term
activator
Definition
A protein that binds to DNA and stimulates gene transcription. In prokaryotes, activators bind in or near the promoter; in eukaryotes, activators generally bind to control elements in enhancers.
Term
alternative RNA splicing
Definition
A type of eukaryotic gene 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.
Term
bicoid
Definition
A maternal effect gene that codes for a protein responsible for specifying the anterior end in Drosophila melanogaster.
Term
control elements
Definition
A segment of non-coding DNA that helps regulate transcription of a gene by serving as a binding site for transcription factor. Multiple control elements are present in a eukaryotic gene’s enhancer.
Term
corepressor
Definition
A small molecule that binds to a bacterial repressor protein and changes the protein’s shape, allowing it to bind to the operator and switch an operon off.
Term
cyclic AMP (cAMP)
Definition
Cyclic adenosine monophosphate, a ring-shaped molecule made from ATP that is common intracellular signaling molecule (second messenger) in eukaryotic cells. It is also a regulator of some bacterial operons.
Term
cytoplasmic determinants
Definition
A maternal substance, such as a protein or RNA, that when placed into an egg influences the course of early development by regulating the expression of genes that affect the developmental fate of cells.
Term
determination
Definition
The progressive restriction of developmental potential in which the possible fate of each cell becomes more limited as an embryo develops. At the end of determination, a cell is committed to its fate.
Term
differential gene expression
Definition
The expression of different sets of genes by cells with the same genome.
Term
differentiation
Definition
The process by which a cell or group of cells become specialized in structure and function.
Term
DNA methylation
Definition
The presence of methyl groups on the DNA bases (usually cytosine) of plants, animals and fungi. (The term also refers to the process of adding methyl groups to DNA bases.
Term
egg-polarity genes
Definition
A gene that helps control the orientation (polarity) of the egg; also called a maternal effect gene.
Term
embryonic lethals
Definition
A mutation with a phenotype leading to death of an embryo or larva.
Term
enhancers
Definition
A segment of eukaryotic DNA containing multiple control elements, usually located far from the gene whose transcription it regulates.
Term
epigenetic inheritance
Definition
Inheritance of traits transmitted by mechanisms not directly involving the nucleotide sequence of a genome.
Term
histone acetylation
Definition
The attachment of acetyl groups to certain amino acids of histone proteins.
Term
homeotic genes
Definition
Any of the master regulatory genes that control placement and spatial organization of body parts in animals, plants and fungi by controlling the developmental fate of groups of cells.
Term
inducer
Definition
A specific small molecule that binds to a bacterial repressor protein and changes the repressor’s shape so that it cannot bind to an operator, thus switching an operon on.
Term
induction
Definition
The process in which one group of embryonic cells influences the development of another, usually by causing changes in gene expression.
Term
maternal effect gene
Definition
A gene that, when mutant in the mother, results in a mutant phenotype in the offspring, regardless of the offspring’s genotype. Maternal effect genes, also called egg-polarity genes, were first identified in Drosophila melanogaster.
Term
microRNAs (miRNAs)
Definition
A small, single-stranded RNA molecule, generated from a hairpin structure on a precursor RNA transcribed from a particular gene. The miRNA associates with one or more proteins in a complex that can degrade or prevent translation of an mRNA with a complementary sequence.
Term
morphogenesis
Definition
The cellular and tissue-based process by which an animal body takes shape.
Term
morphogens
Definition
A substance, such as Bicoid protein in Drosophila, that provides positional information in the form of a concentration gradient along an embryonic access.
Term
morphogens
Definition
A substance, such as Bicoid protein in Drosophila, that provides positional information in the form of a concentration gradient along an embryonic access.
Term
oncogenes
Definition
A gene found in viral or cellular genomes that is involved in triggering molecular events that can lead to cancer.
Term
operator
Definition
In bacterial and phage DNA, a sequence of nucleotides near the start of an operon to which an active repressor can attach. The binding of the repressor prevents RNA polymerase from attaching to the promoter and transcribing the genes of the operon.
Term
operon
Definition
A unit of genetic function found in bacteria and phages, consisting of a promoter, an operator and a coordinately regulated cluster of genes whose products function in a common pathway.
Term
p53 gene
Definition
A tumor-suppressing gene that codes for a specific transcription factor that promotes the synthesis of proteins that inhibit the cell cycle.
Term
pattern formation
Definition
The development of a multicellular organism’s spatial organization, the arrangement of organs tissues in their characteristic places in three-dimensional space.
Term
positional information
Definition
Molecular cues that control pattern formation in an animal or plant embryonic structure by indicating a cell’s location relative to the body’s axes. These cues elicit a response by genes that regulate development.
Term
proteasomes
Definition
A giant protein complex that recognizes and destroys proteins tagged for elimination by the small protein ubiquitin.
Term
proto-oncogenes
Definition
A normal cellular gene that has the potential to become an oncogene.
Term
ras gene
Definition
A gene that codes for Ras, a G protein that relays a growth signal from a growth factor receptor on the plasma membrane to a cascade of protein kinases, ultimately resulting in stimulation of the cell cycle.
Term
regulatory gene
Definition
A gene that codes for a protein, such as a repressor, that controls the transcription of another gene or group of genes.
Term
repressor
Definition
A protein that inhibits gene transcription. In prokaryotes, repressors bind to the DNA in or near the promoter. In eukaryotes, repressors may bind to control elements within enhancers, to activators, or to other proteins in a way that blocks activators from binding to the DNA.
Term
RNA interference (RNAi)
Definition
A technique used to silence the expression of selected genes. RNAi uses synthetic double-stranded RNA molecules that match the sequence of a particular gene to trigger the breakdown of the gene’s messenger RNA.
Term
small interfering RNAs (siRNAs)
Definition
One of multiple small, single-stranded RNA molecules generated by cellular machinery from a long, linear, double-stranded RNA molecule. The siRNA associates with one or more proteins in a complex that can degrade or prevent translation of an mRNA with a complementary sequence. In some cases, siRNA can also block transcription by promoting chromatin modification.
Term
tumor-suppressor genes
Definition
A gene whose protein product inhibits cell division, thereby preventing the uncontrolled cell growth that contributes to cancer.
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