Joke Collection Website - Joke collection - Why should semi-conservative replication of DNA be marked with n instead of p?

Why should semi-conservative replication of DNA be marked with n instead of p?

Firstly, human cells were amplified on the medium containing nitrogen 15 and ordinary medium, and two kinds of cells were obtained, namely, nitrogen-containing DNA 15 and nitrogen-containing DNA 14 without nitrogen 15. The next step is to transfer the cells containing nitrogen 15DNA into common culture medium.

After one generation, the same number of three kinds of cells were centrifuged with cesium chloride density gradient. Because of the different isotope densities, a new band appeared between the DNA molecules of nitrogen fifteen and nitrogen fourteen. Compared with the first generation, the two generations of cell centrifugation found that the hybrid DNA containing two kinds of nitrogen did not increase.

The semi-conservative replication of DNA illustrates the mechanism of DNA replication in all known cells. The name of semi-conservative replication comes from the fact that in the two sub-DNA copies produced by replication, each copy of DNA double strand contains a parent DNA single strand and a newly synthesized DNA single strand.

Extended data:

DNA replication is a process of melting replication. At the beginning of replication, DNA molecules first use the energy provided by cells to untie two spiral double strands under the action of helicase. This process is called unwinding.

Then each untied mother chain is used as a template, and four kinds of deoxynucleotides in the surrounding environment are used as raw materials. According to the principle of base complementary pairing, under the action of related enzymes, a sub-chain complementary to the mother chain is synthesized respectively. With the unwinding process, the newly synthesized sub-chains extend continuously, and at the same time, each sub-chain and its corresponding parent chain curl into a double helix structure, thus forming new DNA molecules.

In this way, after replication, one DNA molecule forms two identical DNA molecules. Two newly replicated daughter DNA molecules are distributed to daughter cells through cell division.

Baidu Encyclopedia-Semi-conservative Replication