how to form the hereditary table that is made by Mendel?
Answers
Mendel created a model that accounted for these and other data he got from his breeding experiments. The following summarizes the model's first basic feature.
Mendel's model for the F1 generation is summarized in the table at the right. The model states that each trait is controlled by a pair of hereditary packets we now call genes. One packet comes from each parent. The alleles (= forms) of the gene for height are the same in true breeding plants ( T T and t t parent plants ). Cross breeding T T with t t plants produces T t plants in the first or F1 generation. The F1 plants receive a T allele from the tall parent and a t allele from the short parent. The F1 plants are tall because the T allele is expressed and "cover up" the t allele. So the T (tall) allele is called dominant and t (short) allele is called recessive.
The diagram at the right shows how Mendel's model explains the 3:1 ratio of tall to short plants in the F2 generation. In the F1 generation each plant had one T and one t allele of the gene controlling height. Plants in the F2 generation had a 50:50 chance of getting a T or a t from each parent plant. The diagram shows that this results in 1 out of 4 plants getting only t genes and 3 plants getting at least one T gene (which makes the plant tall, because T is dominant over t)
The diagram also shows that the F2 generation actually has three kinds of plants. 1/4 are t t plants, which are short and produce only short plants in following generations in self pollinated. Of the remaining 3/4 tall plants, 1/4 are T T, which are tall and produce only tall plants in following generations if self pollinated. The remaining 2/4 get a T from one parent and at from the other. When self pollinated, they produce a pattern exactly like the F1 generation: 1 short plant for every 3 tall plants. These plants are exactly like the F1 generation.