Finally, proteins products can be subjected to modifications such as phosphorylation or dephosphorylation to alter their functions, or can be completely degraded to turn off a gene. Some genes do not encode proteins but short forms of RNAs with regulatory functions such as induction of flowering. Regulation of gene expression at the level of transcription can be brought about through chromatin and histone modifications. Also, a gene sequence can be differentially spliced to produce mRNA products of variable lengths leading to new protein products with novel functions. expression levels can be modulated “up” or “down”). Fluctuations in the intensities of external stimuli coupled to changes that occur at the genomic level result in different developmental outcomes or physiological states. gene expression is either “on” or “off”) or quantitative (i.e. The expression of genes in specific plant cells, tissues, and organs and the timing of this expression require a precise level of regulation. Expression, or genetic function, can potentially be regulated at any of the steps from transcription, RNA processing, translation, through post-translational protein modification, as discussed in lesson 1. Regulation can be qualitative (i.e. However, it sometimes occurs that a transcript might be produced but not a protein, or that a protein is produced but it is in an inactive state. In such cases, although a gene product is produced, the biological activity encoded by that gene is not present. For the purposes of this section, the key point is how the biological activity encoded by a gene is regulated. Typically, if a gene product is produced, the gene is considered “expressed”. The term expression can be used in different ways that are sometimes confusing. This regulation of activity is known as gene expression. This is achieved by regulating the activity of genes according to the physiological demands of a particular cell type, developmental stage, or environmental condition. Understand post-translational protein modification and regulation.Įvery cell in a plant contains the same genetic information, the same set of genes. Yet Therefore different sets of genes are required for the various functions of different cells or tissues, as well as for plant responses to environmental stimuli or stresses.Understand post-transcriptional regulation of gene expression (RNA level).Understand transcriptional regulation of gene expression.Understand the concept of gene expression.
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