Gene Expression
Gene expression is the most fundamental process that organisms undergo to perform the cellular functions required for life. Gene expression can also be manipulated in the lab to take genes wanted from one organism and express that gene in another organism of interest. Genes are expressed in a two-step process called transcription and translation.
The first step towards gene expression is transcription. A gene is located within the genomic DNA of a cell. The genomic DNA is similar to a blueprint in that it contains all the information needed to build each components of the cell. These components are all proteins. Transcription begins with RNA polymerase making a copy of the template strand of the gene of interest to form a single stranded RNA called messenger RNA. Once messenger RNA is made, it proceeds to the next step called translation.
In the last few years, rapid progress has been made in mapping every gene of every organism due to high throughput sequencing techniques. As a result of this, any kind of gene encoding for any type of protein can be found online in a gene databank. In the lab the gene of interest can be obtained by looking at the computer database instead of having proteins scan genomic DNA like it does in a cell. While a cell is limited to take a certain portion of its own genomic DNA and convert it into mRNA for gene expression, scientists are able to synthetically synthesize genes from any organism and insert it into a vector for gene expression to take place. All of this is only possible due to advances in gene sequencing and gene synthesis.
The last step toward gene expression is translation. Weather the gene of interest was obtained by the cell or by laboratory manipulation; translation occurs naturally using cellular proteins called ribosomes. Once mRNA is made, it is tagged with a poly-A tail which guides the mRNA outside the nuclear pores of the nucleus to the ribosomes of the cell. Within the ribosomes, mRNA is finally expressed into genes. Gene expression is defined as the portion of genomic DNA (a gene) which can be expressed into a protein.
In summary, gene expression is a complex process that occurs within the cell to express proteins of interest. Due to advancements in technology, genes from any type of organism can be synthetically made and expressed into a wide variety of hosts. These advancements in gene expression techniques will and have led to discoveries in therapeutic research.