The expression of biological genes refers to the transcription and translation process of genes in organisms, from DNA to RNA to protein synthesis. This process is an essential link in the normal life cycle of organisms, which is of great significance for maintaining the normal function of organisms and the transmission of genetic information.
The expression of biological genes is regulated by many factors, including genetic factors and environmental factors. Understanding the expression mechanism of biological genes is of great significance for understanding the development, growth and adaptation of organisms.
1, gene transcription
Gene transcription refers to the replication process of DNA information in RNA. It includes three main stages: beginning, continuation and termination. In the start-up stage, RNA polymerase binds to DNA, unlocks double strands from DNA, and forms transcription vesicles. In the extension stage, RNA polymerase moves forward along the DNA chain to synthesize RNA chain. In the termination stage, the transcription termination signal recognition factor interacts with RNA polymerase, resulting in the detachment of RNA chain.
2. Post-transcriptional modification
Post-transcriptional modification refers to the formation of mature RNA molecules through a series of modification processes. Splicing refers to the removal of intron sequences in transcribed RNA molecules and the connection of exon sequences. Modification refers to the chemical modification of RNA molecules, such as methylation and acetylation. Processing refers to modifying both ends of RNA molecules, such as adding hat structure and tail.
3. Translation
Translation refers to the process of translating the encoded information on mRNA into protein in cytoplasm. It includes three main stages: start-up, expansion and termination. In the initial stage, mRNA combines with small nucleolar RNA and promoter, and interacts with ribosomes.
In the extension stage, tRNA carries amino acids and supplements codons on mRNA to synthesize protein chain. In the termination stage, when the stop codon appears, the stop factor interacts with mRNA, resulting in the detachment of protein chain.
4. Gene regulation
Gene regulation plays an important role in gene expression. These controls can occur in all aspects of transcription and translation. In transcription regulation, transcription factors combine with promoters on DNA sequences to promote or inhibit transcription. In translation regulation, the stability and translation rate of mRNA are influenced by regulatory factors.
5. Cell specificity
In multicellular organisms, various cells have different shapes and functions. These cell specificities are achieved through the regulation of gene expression. Different cells have differences in gene expression level, that is, some genes are only expressed in specific cells. This cell-specific regulation is mainly achieved through transcription factors and epigenetic mechanisms. The expression pattern and regulatory network of transcription factors determine the difference of cell-specific gene expression.