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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 |
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| A unit of genetic function found in bacteria and phage DNA, consisting of a promoter, an operator, and a coodinately regulated cluster of genes whose products function in a common pathway. |
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| The repressor binds to the operator and blocks the attachment of RNA polymerase to the promoter, which prevents transcription of that gene. (a repressor is a protein)... The binding of a repressor is reversible... It is only in active form (with can bind to promoter) if it has a specific ligand bound to its active site, so if that ligand is not there then it is in the inactive form. |
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| A gene that codes for a protein, such as a repressor, that controls the transcription of another gene or group of genes |
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| A small molecule that cooperates with a repressor protein to switch an operon off. |
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| Transcription is usually "on" but can be inhibited when a specific small molecule binds allosterically to a regulatory protein |
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| Transcription is usually "off" but can be stimulated when a specific small molecule interacts with a regulatory protein. |
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| A specific small molecule that binds to a bacterial repressor protein and changes the repressors shape so that it cannot bind to an operator, thus switching an operon ON |
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| Negative control of genes |
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Definition
| The operons are switched off by the active form of the repressor protein. |
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| Positive control of genes |
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| When a regulatory protein interacts directly with the genome to switch transcription on. |
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| A protein that binds to DNA and stimulates transcription of a gene |
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| Differential gene expression |
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Definition
| The expression of different genes by cells with the same genome. |
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| acetyl groups are attached to lysines in histone tails...(deacetylation is the removal of acetyl groups, this is referred to as "silencing" the gene)... when lysines are acetylated, their positive charge is nuetralized, and histone tails no longer interact with neighboring nucleosomes. When this happens, transcription proteins can more readily attach to genes in the acetylated region |
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| Specific combinations of modifications, as well as the order in which they have occured, help determine the chromatin configuration, which in turn influences transcription. |
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| The presence on methyl groups on the DNA bases (usually cytosine) of plants, animals and fungi... In general, areas that are not transcribed tend to be more methylated than regions that are frequently transcribed... Thus the removal of methyl groups can lead to certain genes being "turned on.".... can be used for Genomic imprinting in mammals. |
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| Inheritance of traits transmitted by mechanisms not directly involving the nucleotide sequence |
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| Segments of noncoding DNA that serve as binding sites for the proteins called transcription factors, which in turn regulate transcription |
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| General transcription factors |
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Definition
| Transcription factors that are essential for the transciption of all protein coding genes. |
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| Specific transcription factors |
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Definition
| In eukaryotes, high levels of transcription of particular genes at the appropriate time and place depend on the interaction of control elements with another set of proteins, which can be thought of as specific transcription factors. |
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| A segment of eukaryotic DNA containing multiple control elements, usually located far from the gene whose transcription it regulates... A gene may have multiple enhancers, each active at a different time or in a different cell type or location in the organism... Each enhancer is generall associated with only that gene and no other. |
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| Areas of the nucleus where loops of different chromosomes can interact with each other... tend to be rich with RNA polymerases and other transcription associated proteins... are thought to be areas specialized for a common function. |
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| in bacteria, it tends to be quite fast, usually a few minutes... In eukaryotes, mRNA can last hours, days and even weeks... Amount of time that mRNA remains intact correlates with the length of the untranslated region (UTR) at the 3' end. |
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| Initiation of translation regulation |
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Definition
| Translation can be blocked by regulatory proteins that bind to the 5' or 3' UTR. |
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| A giant protein complex that recognizes and destroys proteins tagged for elimination by the small protein ubiquitin |
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| noncoding RNA... it is functinal RNA that is not translated to a protein. |
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| microRNA... small single stranded RNA molecules... capable of binding to complementary sequences in mRNA molecules... miRNA are formed from longer RNA precursors that fold back on themselves, forming one or more double stranded hairpin structures, each held together by hydrogen bonds. Each hairpin is cut away from the precursor and trimmer by an enzyme (Dicer), into short double stranded fragments 22 nucleotides pairs. One strand in degraded and the other strand (miRNA), the miRNA forms a complex with a protein... This complex can bind to any mRNA that has a 7-8 nucleotide complementary sequence. The complex may then degrade the mRNA or block it for translation |
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| RNA interference...A technique used to silence the expression of genes. RNAi uses synthetic double stranded RNA molecules that match the sequence of a particular gene to trigger the breakdown of the gene's mRNA. |
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| small interfering RNA...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 mRNA with a complementary sequences. In some cases, siRNA can also block transcription by promoting chromatin modification |
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| piRNAs... induce the formation of heterochromatin, blocking the expression of some parasitic DNA elements in the genome known as transposons... piRNA are usually 24-31 nucleotides long, they play a role in gamete formation, by re-establishing methylation patterns in the genome during gamete formation. |
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| The three processes that give rise of a zygote and the organism it becomes? |
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| Cell division (mitosis), cell differentiation, and morphohenesis |
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| The process by which cells become specialized in structure and function. |
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| The cellular and tissue based processes by which an animal body takes shape. |
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| Maternal substances in the egg that influence the course of early development.... the cytoplasm is not homogeneous, so when the zygote begins to separate into different cells, the nuclei are exposed to different cytoplasmic determinants |
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| The process in which one group of embryonic cells influence the development of another, usually by causing changes in gene expression |
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| The progressive restriction of development 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 |
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| The development of a multicellular organism's spatial organization, the arrangement of organs and tissues in their characteristic places in three dimensional space... cytoplasmic determinants and inductive signals both contribute to pattern formation. |
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| The molecular cues that control pattern formation... are provided by cytoplasmic determinants and inductive signals |
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| The genes that control pattern formation in the late embyo, larva and adult. |
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| Mutations with phenotypes causing death at the embryonic or larval stage. |
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| Is a gene that, when mutant in the mother, results in a mutant phenotype in the offspring regardless of the offsprings own genotype... Also called egg-polarity genes |
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| A maternal effect gene that codes for a protein responsible for specifying the anterior end in Drosophilia... causes offspring to have two tails |
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| A substance that provides positional information in the form of a concentraion gradient along the embryonic axis. |
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| Cancer causing genes in certain types of viruses |
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| The normal versions of cellular genes that code for proteins that stimulate normal cell growth and division |
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| The proteins they encode help prevent uncontrolled cell growth. |
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| (rat sarcoma, a connective tissue in cancer)... Is a G protein that relays a signal from a growth factor receptor on the plasma membrane to a cascade of protein kinases |
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| is a tumor suppressor gene... named for the 53,000-dalton molecular weight of it protein product |
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