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Principles of Biology
Published in Arthur T. Johnson, Biology for Engineers, 2019
Crosses between homozygous-dominant and homozygous-recessive individuals (for one particular genetic trait) will give all heterozygous offspring that express the dominant trait (Figure 5.3.6). Crosses between two heterozygous individuals will, on average, yield one-quarter homozygous-dominant offspring, one-quarter homozygous-recessive offspring, and one-half heterozygous offspring (Figure 5.3.6). Three quarters of these offspring will, therefore, exhibit the dominant form of the trait, and only the homozygous-recessive offspring will exhibit the recessive form. Gregor Mendel observed these results with his classic experiments on peas with white (recessive) and purple (dominant) flowers. It was his pioneering work that showed that genetic characteristics did not blend together, but instead retained their essential qualities (Hellman, 1998).
Advance intervention of recessive ill-conditioned feature: the early-stage design method based on system recessive inheritance
Published in Journal of Engineering Design, 2023
Zifeng Nie, Peng Zhang, Fang Wang
In biology, inheritance can be divided into dominant inheritance and recessive inheritance. Dominant inheritance is controlled by dominant genes. On homologous chromosomes, when two homologous dominant genes exhibit in pairs, or when dominant and recessive genes integrate as alleles, dominant traits will appear. Recessive inheritance indicates that the parents carry certain genes that do not show the trait explicitly. When these genes are passed on to the offspring, the recessive traits may be triggered to be dominant when the recessive genes are homozygous. In the genetic process of organisms, recessive inheritance plays a significant part in view of that the exhibition of some rare traits in organisms is often related to the manifestation of homozygous recessive genes, as shown in Figure 2(a). A recessive gene will not incur an ill-conditioned trait when the allele is dominant. Even in the course of multiple generations, this kind of ill-conditioned traits is hidden. Only if a pair of recessive genes become alleles during the process of inheritance, that is homozygous for the recessive gene, will the ill-conditioned traits incurred by the recessive gene exhibit distinctly. It is notable that most of the recessive ill-conditioned features that appear in organisms are ensured by homozygosity of recessive genes (Clark and Pazdernik 2013; Nambisan 2017; Wahlsten 2019).