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The secret hidden in DNA: Why do some alleles not affect appearance characteristics?
In the world of genetics, alleles play an important role in determining the appearance characteristics of organisms. Some alleles can significantly change a person's appearance, while others have only a minimal effect on physical characteristics. What are the differences between these alleles that make them behave differently? This is a thought-provoking question.
Alleles are nucleotide sequence variations located at specific locations on DNA and may vary at a single location or include insertions or deletions of thousands of base pairs.
Each allele has the potential to affect the function of the gene product, but the observed variation in most alleles causes little change in the function of the gene product. This means that when we evaluate a genotype, we cannot always predict the traits it will exhibit. Take Mendel's famous pea flower color as an example. The white and purple flower colors are actually determined by a pair of alleles. This discovery changed our understanding of inheritance.
Many multicellular organisms possess two sets of chromosomes throughout their biological life cycle, indicating that they are diploid. When two chromosomes have the same allele at a certain position, the organism is said to be homozygous; if the alleles are different, the organism is said to be heterozygous. The common understanding of "alleles" often only refers to different alleles in a gene. A clear illustration of this concept is the example of the ABO blood group, which has six common alleles.
The term "wild-type" allele is often used to describe an allele thought to contribute to the species' typical phenotypic characteristics, a trait seen in many wild organisms.
In addition, the 1995 classification of phenotypes made us realize that many characteristics are not simply dominant or recessive, but have co-dominance and polygenic inheritance. The complexity of these phenotypes allows us to understand that even within the DNA sequence, the influence of genes is not always obvious.
Taking human blood types as an example, the complex relationship between ABO blood types illustrates how multiple alleles affect phenotypic performance. Each person may have a different genotype, resulting in a different phenotype. This also brings attention to how to interpret the interaction of recessive and dominant alleles.
In terms of the diversity of genetic diseases, many genetic diseases occur due to individuals inheriting two recessive alleles.
As science advances, we have come to realize that most or all genetic loci are polymorphic, possessing multiple alleles. This complicates the relationship between allele frequency and phenotypic variation within a population. Even if allele frequencies differ significantly between groups, this does not completely change the results for appearance characteristics.
Furthermore, phenotypic variation may also be closely related to the influence of epigenetics. Research continues to show that certain epigenetic marks can be passed down from generation to generation in certain organisms. This phenomenon has important implications for our understanding of gene expression and its impact on appearance.
"Epi alleles" refer to a type of genetic markers that are used to strictly distinguish genetic markers in addition to traditional alleles, and are receiving more and more attention in the study of genetic variation.
In the process of genetic research on organisms, whether it is about allelic diversity or epigenetic marks, the challenge that scientists face is how to accurately capture these complex factors to understand organisms more clearly. Phenomenon. So think of the "allele" amplitude as a multi-layered genetic puzzle, with each piece representing a possible manifestation that is still waiting to be revealed.
This series of complex genetic mechanisms not only changes our understanding of how genes affect phenotypic characteristics, but also makes us think about how many secrets we have not yet explored hidden in these seemingly hidden alleles?
