(Continued from the previous issue)
The place where cells synthesize proteins is a "gourd"-like ribosome. When we "transformed" and "entered" the cytoplasm, we found that a messenger RNAz that had just come from the nucleus of the cell was being "stuck" on the "neck" of the "gourd" ribosome, and many objects shaped like "clover" were busy going in and out of the "gourd", they all went in with an amino acid, and the amino acid they came out with was gone. This "clover"-like object is the tool for transporting amino acids – transporting RNA. Since there are 20 amino acids that synthesize all proteins, and each amino acid has a specific transporter RNA, there are also 20 transporter RNAs. Each transporter RNA has three bases at one end that pairs with the base of the messenger RNA, and at the other end of the transporter RNA is its "arm" that grabs amino acids free inside the cytoplasm.
When the transport RNA carries amino acids into the ribosome, the messenger RNA is used as a template, and the transported amino acids are placed in the corresponding position according to the principle of base pairing. The transporter RNA leaves the ribosome after dropping the amino acids and then transports the same amino acid. As a result, different transporter RNAs carry different amino acids into the ribosome according to the order in which the messenger RNA bases are arranged, and connect them one by one to form chains, and the transport RNA will only stop working when stop codons appear on the messenger RNA strands. At this time, the amino acid chains that have been connected in the front will fall off in the ribosome and become a protein with a certain amino acid order.
The scientists also found in their studies that the genetic material of some viruses is not DNA, but RNA, and they call these viruses RNA viruses, such as AIDS. Scientists also found that the virus can be transformed from RNA to DNA when it reproduces, a process that runs counter to DNA transcription into RNA, so it is called reverse transcription, so the complete central law should also be added - RNA reverse transcription into DNA. This is an important addition to the "central law".
Scientists have now been able to copy, transcribe and translate the DNA of cells in test tubes, and have formed genetic engineering on this basis. With genetic engineering, agronomists can grow plants like never before; medical scientists can treat some stubborn diseases that were difficult to cure in the past; biologists can use cloning techniques to replicate animals; pharmacists can make very expensive proteins in vitro or on animals that were originally only extracted from human tissues; geneticists can decipher all the secrets contained in human genes... It is no exaggeration to say that the central law is the foundation of all the achievements of modern molecular biology.
(Full text completed)