Labelled diagram of Independent inheritance of two separate traits, shape, and colour of seeds

Labelled diagram of Independent inheritance of two separate traits, shape, and colour of seeds

Labelled diagram of Independent inheritance of two separate traits, shape, and colour of seeds: Cellular DNA is the information source for making proteins in the cell. A section of DNA that provides information for one protein is called the gene for that protein. Take the example of tallness as a characteristic. We know that plants have hormones that can trigger growth. Plant height can thus depend on the amount of a particular plant hormone. The amount of the plant hormone made will depend on the efficiency of the process for making it.

Consider now an enzyme that is important for this process. If this enzyme works efficiently, a lot of hormone will be made, and the plant will be tall. If the gene for that enzyme has an alteration that makes the enzyme less efficient, the amount of hormone will be less, and the plant will be short. Thus, genes control characteristics, or traits. If the interpretations of Mendelian experiments we have been discussing are correct, then both parents must be contributing equally to the DNA of the progeny during sexual reproduction. We have disscussed this issue in the previous Chapter.

If both parents can help determine the trait in the progeny, both parents must be contributing a copy of the same gene. This means that each pea plant must have two sets of all genes, one inherited from each parent. For this mechanism to work, each germ cell must have only one gene set.

If progeny plants inherited a single whole gene set from each parent, then the experiment explained in Fig. 9.5 cannot work. This is because the two characteristics ‘R’ and ‘y’ would then be linked to each other and cannot be independently inherited. This is explained by the fact that each gene set is present, not as a single long thread of DNA, but as separate independent pieces, each called a chromosome.

Thus, each cell will have two copies of each chromosome, one each from the male and female parents. Every germcell will take one chromosome from each pair and these may be of either maternal or paternal origin. When two germ cells combine, they will restore the normal number of chromosomes in the progeny, ensuring the stability of the DNA of the species. Such a mechanism of inheritance explains the results of the Mendel experiments, and is used by all sexually reproducing organisms. But asexually reproducing organisms also follow similar rules of inheritance.

Independent inheritance of two separate traits, shape and colour of seeds diagram

Labelled diagram of Independent inheritance of two separate traits, shape, and colour of seeds for 10th standard

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Updated: March 7, 2023 — 4:57 pm

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