Porteous John W
Department of Molecular and Cell Biology, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, Scotland, UK.
Theor Biol Med Model. 2004 Aug 31;1:6. doi: 10.1186/1742-4682-1-6.
The key to a rational treatment of elementary Mendelian genetics, specifically to an understanding of the origin of dominant and recessive traits, lies in the facts that: (1) alleles of genes encode polypeptides; (2) most polypeptides are catalysts, i.e. enzymes or translocators; (3) the molecular components of all traits in all cells are the products of systems of enzymes, i.e. of fluxing metabolic pathways; (4) any flux to the molecular components of a trait responds non-linearly (non-additively) to graded mutations in the activity of any one of the enzymes at a catalytic locus in a metabolic system; (5) as the flux responds to graded changes in the activity of an enzyme, the concentrations of the molecular components of a trait also change.
It is then possible to account rationally, and without misrepresenting Mendel, for: the origin of dominant and recessive traits; the occurrence of Mendel's 3(dominant):1(recessive) trait ratio; deviations from this ratio; the absence of dominant and recessive traits in some circumstances, the occurrence of a blending of traits in others; the frequent occurrence of pleiotropy and epistasis.
合理处理孟德尔遗传学基本原理,特别是理解显性和隐性性状起源的关键在于以下事实:(1)基因的等位基因编码多肽;(2)大多数多肽是催化剂,即酶或转运蛋白;(3)所有细胞中所有性状的分子成分都是酶系统的产物,即流动代谢途径的产物;(4)对代谢系统中催化位点上任何一种酶活性的分级突变,性状分子成分的任何通量反应都是非线性的(非加性的);(5)随着通量对酶活性分级变化的反应,性状分子成分的浓度也会发生变化。
这样就有可能在不歪曲孟德尔理论的情况下,合理地解释:显性和隐性性状的起源;孟德尔3(显性):1(隐性)性状比例的出现;与该比例的偏差;某些情况下显性和隐性性状的缺失,其他情况下性状的混合出现;多效性和上位性的频繁出现。