Thus, control of these processes plays a critical role in determining what proteins are present in a cell and in what amounts.
In certain cases, some introns or exons can be either removed or retained in mature mRNA. Gene Expression and Regulation Gene expression Gene expression is the process by which the genetic code - the nucleotide sequence - of a gene is used to direct protein synthesis and produce the structures of the cell.
Of course, there are many cases in which cells must respond quickly to changing environmental conditions. The resulting mRNA is a single-stranded copy of the gene, which next must be translated into a protein molecule.
A similar site in vertebrates was characterized by Marilyn Kozak and is thus known as the Kozak box. Different transcription factors can turn on at different times during successive generations of cells.
While working with a CDC team in Mexico, Jason is the only person who does not get sick from a new strain of flu. As cells mature and go through different stages arrowstranscription factors colored balls can act on gene expression and change the cell in different ways. Main article: Post-transcriptional regulation In eukaryotes, where export of RNA is required before translation is possible, nuclear export is thought to provide additional control over gene expression.