What Are Retroviruses?

Reverse transcription uses RNA as a template to synthesize DNA, that is, DNA synthesis under the guidance of RNA. In this process, the process of nucleic acid synthesis and transcription (DNA to RNA) is opposite to the flow direction of genetic information (RNA to DNA), so it is called reverse transcription. Reverse transcription is one of the replication forms of RNA viruses. Reverse transcription also exists in eukaryotic cells. For example, the retrotransposon and elongation of telomere DNA both exist in the reverse transcription process and need to be catalyzed by reverse transcriptase. The discovery of the reverse transcription process is a major discovery in molecular biology research, and it is an important amendment and supplement to the central law. By simulating this process in vitro, people use the extracted mRNA as a template to synthesize complementary cDNA under the action of reverse transcriptase, construct a cDNA library, and select specific target genes from it. This method has become one of the most commonly used strategies for obtaining target genes in genetic engineering technology.

Reverse transcription

Reverse transcription

The reverse transcription process consists of

The discovery of reverse transcription has important theoretical and practical significance.

(1) The central law of molecular biology has been revised and supplemented. The classic central law holds that the function of DNA is both the transmission and expression of genetic information, so DNA is at the center of life activities. The phenomenon of reverse transcription indicates that at least in some organisms, RNA also has the function of transmitting genetic information and expression. The revised central law is expressed as: refers to the process of transmitting genetic information from DNA to RNA, and then from RNA to proteins, to complete the transcription and translation of genetic information. It can also be passed from DNA to DNA, that is, the DNA replication process is completed. This is the rule followed by all organisms with cellular structures. The RNA in some viruses replicates itself (such as tobacco mosaic virus, etc.) and in some viruses can be reverse transcribed into DNA using RNA as a template (some oncogenic viruses). Some protein viruses (ie prions, such as mad cow disease virus) form proteins directly from proteins (for example, mad cow disease virus is a structurally abnormal protein formed by misfolding, which can cause the same folding errors as proteins with the same amino acid sequence itself Leading to the formation of a large number of structurally abnormal proteins).

(2) Oncogenes have been discovered in the research of oncogenic viruses. In some human cancer cells, such as bladder cancer, small cell lung cancer, and other cells, the same base sequence as the virus oncogene is also isolated, which is called cell oncogene or protozoan. Oncogene. The discovery of oncogenes provides promising clues for the study of tumor pathogenesis.

(3) Contribute to the implementation of genetic engineering in actual work. Since the transcription product of the target gene is easy to prepare, mRNA can be reverse transcribed to form DNA to obtain the target gene.