By gene expression we mean the transcription of a gene into mRNA and its subsequent translation into protein. Gene expression is primarily controlled at the level of transcription, largely as a result of binding of proteins to specific sites on DNA. In 1965 Francois Jacob, Jacques Monod, and Andre Lwoff shared the Nobel prize in medicine for their work supporting the idea that control of enzyme levels in cells is regulated by transcription of DNA. occurs through regulation of transcription, which can be either induced or repressed. These researchers proposed that production of the enzyme is controlled by an "operon," which consists a series of related genes on the chromosome consisting of an operator, a promoter, a regulator gene, and structural genes. Show
The operator gene is the sequence of non-transcribable DNA that is the repressor binding site. There is also a regulator gene, which codes for the synthesis of a repressor molecule hat binds to the operator
Source: http://biowiki.ucdavis.edu/Under_Construction/BioStuff/BIO_101/Reading_and_Lecture_Notes/Control_of_Gene_Expression_in_Prokaryotes Control of Gene Expression in EukaryotesEukaryotic cells have similar mechanisms for control of gene expression, but they are more complex. Consider, for example, that prokaryotic cells of a given species are all the same, but most eukaryotes are multicellular organisms with many cell types, so control of gene expression is much more complicated. Not surprisingly, gene expression in eukaryotic cells is controlled by a number of complex processes which are summarized by the following list.
Source: http://www.78stepshealth.us/plasma-membrane/eukaryotic-chromosomes.html
Source: http://unmug.com/category/biology/organisation-control-of-genome/
Source: http://www.nbs.csudh.edu/chemistry/faculty/nsturm/CHE450/19_InsulinGlucagon.htm
Source: http://sites.saschina.org/emily01px2016/2014/11/23/a-variety-of-intercellular-and-intracellular-signal-transmissions-mediate-gene-expression/
RNAiSome RNA virus will invade cells and introduce double-stranded RNA which will use the cells machinery to make new copies of viral RNA and viral proteins. The cell's RNA interference system (RNAi) can prevent the viral RNA from replicating. First, an enzyme nicknamed "Dicer" chops any double-stranded RNA it finds into pieces that are about 22 nucleotides long. Next, protein complexes called RISC (RNA-induced Silencing Complex) bind to the fragments of double-stranded RNA, winds it, and then releases one of the strands, while retaining the other. The RISC-RNA complex will then bind to any other viral RNA with nucleotide sequences matching those on the RNA attached to the complex. This binding blocks translation of viral proteins at least partially, if not completely. The RNAi system could potentially be used to develop treatments for defective genes that cause disease. The treatment would involve making a double-stranded RNA from the diseased gene and introducing it into cells to silence the expression of that gene. For an illustrated explanation of RNAi, see the short, interactive Flash module at http://www.pbs.org/wgbh/nova/body/rnai-explained.html The RNA interference system is also explained more completely in the video below from Nature Video.
return to top | previous page | next page Which is the correct order of events during gene expression?Thus, during expression of a protein-coding gene, information flows from DNA → RNA → protein. This directional flow of information is known as the central dogma of molecular biology.
What is postPost-translational control can be defined as the mechanisms by which protein structure can be altered after translation. Proteins are polymers of amino acids, and there are twenty different amino acids. Both the order and identity of these amino acids are important for the role that the protein plays in the cell.
How is gene expression regulated at the postMuch of this post-transcriptional regulation of gene expression occurs through the action of RNA binding proteins and processing factors that associate with RNAs from the initiation of transcription to the eventual death of the RNA in the cytoplasm [1].
What is involved in postIn Summary: Post-TransCRIPTIONAL Control of Gene Expression
This involves the removal of introns that do not code for protein. Spliceosomes bind to the signals that mark the exon/intron border to remove the introns and ligate the exons together. Once this occurs, the RNA is mature and can be translated.
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