What is the composition of variation?

Variation composition means that elements deliberately violate the order in the ordered relationship, making a few individual elements stand out, thus violating the law.

The effect of variation comes from comparison. Through a small amount of irregular contrast, it gives people visual stimulation, forms visual focus, breaks monotony and produces novel and lively visual effects.

SNP mutation and human health;

Single nucleotide polymorphism is a common genetic variation in human beings, and most SNP information is contained in the single nucleotide polymorphism database (dbSNP). In addition to single nucleotide polymorphism, there are countless rare new single nucleotide mutations. In some cases, the co-separation of mutation and disease only occurs in nuclear families or single individuals.

SNP exists widely in human genome, with an average of 65,438+0 in every 500 ~ 65,438+0,000 base pairs. It is estimated that the total number can reach 3 million or more.

SNP located in protein coding region is called coded SNP (cSNP) according to its influence on biological genetic traits.

CSNP can be divided into two types: one is synonymous cSNP (synonymous CSNP), that is, the change of coding sequence caused by SNP does not affect the amino acid sequence translated by protein, and the meaning of mutated base is the same as that of non-mutated base.

The other is non-synonymous cSNP (non-synonymous SNP), which means that the change of base sequence can be changed into protein sequence of transcript translation, thus affecting the function of protein. This change is often the direct cause of the change of biological characters. About half of cSNP is non-synonymous, and cSNP can be divided into missense mutation and nonsense mutation.

Baidu Encyclopedia-Variations