The cellular environment has an impact on cellular function. Adaptation to specific environments is accomplished by controlling the expression of genes that code for the enzymes and proteins essential for survival in a very specific environment. Nutrients, temperature, light, poisons, metals, chemicals, and messages from alternate cells are all factors which influence organic phenomena. Human illnesses and diseases are caused by malfunctions in the management of organic phenomena.
Regulation Gene Expression
Gene expression regulation refers to the cell’s utilisation of a variety of processes to raise or decrease the output of a certain gene product (an RNA or a protein).
Steps of Regulation Gene Expression
Replication Level
At the replication level, mutations which occur during the DNA replication might affect gene expression.
Transcriptional Level
Repressors and activators can influence the transcription of a specific gene at the transcriptional level.
Post-Transcriptional Level
Gene expression is achieved at the post-transcriptional level through post-transcriptional changes like RNA splicing.
Translational Level
RNA interference mechanism, for example, can influence the translation of an mRNA molecule at the translational level.
Post-Translational Level
By manipulating post-translational modifications, the production of a protein can be controlled at the post-translational level.
In prokaryotes, however, gene expression regulation occurs primarily during transcription initiation. It includes activators that regulate gene expression positively and repressors that regulate gene expression negatively.
Lac Operon
E. coli’s lactose operon produces the b-galactosidase protein, which hydrolyses milk sugar into the saccharose & aldohexose.
The DNA of an animal product has three cistrons, or deoxyribonucleic acid fragments, each of which codes for a specific macromolecule. Cistrons encode proteins that can operate on their own or as subunits of bigger enzymes or the structural proteins.
b-galactosidase is encoded by the Z gene. The Y gene genes for a permease that aids lactose uptake into the bacteria. The A gene encodes the Thiogalactoside Transacetylase with little known function. All three of the genes are transcribed as a single polycistronic mRNA. Multiple genetic messages are contained in polycistronic RNA, each having its own journey initiation & termination signals.
Lac Operon Regulation Gene Expression
Two distinct proteins regulate the activity of promoter which governs the expression of animal product DNA. One protein hinders RNA enzyme from the transcribing (negative control), while the other promotes the RNA enzyme’s attachment to promoter (positive control).