Homework SourseRead through the review article on Mendels traits paying att
Solution
The proposed \"function of the gene\" found for the following Mendel\'s traits such as seed shape, stem length, cotyledon and flower color:
See shape: the gene functions for the expression of seed shape either round or wrinkled as per dominant genotype locus expression for seed coat in the phenotypes.
Stem length: Mendel has used this gene i.e. LE gene to control gibberellin levels finally to determine plant growth and their level of inhibitors based on this gene expression
Mendel’s genes for cotyledon color: this trait was determined by the functions of gene expression in the offspring by controlling plant senescence & chlorophyll degradation significantly. It has represented by symbol \"I\"
Flower color: white flowers ---> gene a2; purple dominant flower color trait ---> gene A & these are expressed for the generation of flavonoid biosythesis, chalcone synthase to produce flower color as per their expression in the offspring
Speculations:
Mendel used pure-breeding lines of peas for his experiments because these pure breeding pea plants can produce offspring with “same traits” as parent plant. These progeny pea plants can cross-bred to generate progeny with recorded genetic phenotypic traits over several generations.
Mendel’s results allowed him to reject the hypothesis of blending inheritance because pure- bred lines of pea plants allowed him to differentiate “dominant trait” & “recessive trait” over subsequent generations according to law of segregation. He has concluded that “traits were not blended” however these traits were remained distinct in subsequent generations, it is contrary speculation at that time. He could not define the genes as unit factors for these traits.
A classic debate in early genetics and evolution is how to create a model that accounts for the discrete traits (pea texture, flower color) observed by Mendel. Mendel has examined the regularity and reproducibility of the trait and the specific transmission from parents to subsequent generation finally reappeared. For example, he observed that white flower color reappearance in the 3rd generation after two crosses and finally deduced that there are physical particles that were transmitted from generation to generation representing a trait, as an evolutionary aspect. He could not observe these unit factors or unit particles as \"genes\" & their functions as he did not know initially anything about chromosomes. This gene has different forms often referred as alleles representing phenotypic features of the offspring. Mendel did not observe \"unit factors\" (genes) directly, he was able to associate the behavior of chromosomes during meiosis to his principles of segregation and independent assortment. Therefore, Mendel’s experiments a challenge for evolutionary models, as he could not observe these unit factors. Later, this conflict of examining the evolutionary inheritance of phenotypic traits as some times some of gene phenotypic features are dominant due to recessive nature of other gene caused by dominant gene therefore predictable ratios in crosses supported the hypothesis of two hereditary elements involved in the expression of a given trait.
