"Science and Biotechnology Books Made Simple" |
"Science and Biotechnology Books Made Simple" |
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Case No 3 The Pea Plant Gregor Mendel, a monk known as the 'Father of Genetics', liked to experiment with pea plants. He first pollinated garden peas that were identical (tall). The offspring were all tall. He then pollinated garden peas that were not identical. One pea plant was tall, and the other was short. Mendel found that all the offspring were again tall. From the above experiment, what did Mendel conclude about the trait (known also in genetics as phenotype) tall? Hint: When one trait dominates the other, it is referred as dominant. When the trait does not dominate, it is referred as recessive.
Each plant carries two copies of a hereditary component. They are referred to as alleles. One allele comes from one parent, the other from the other parent. Alleles pass into different reproductive cells, called gametes. When an allele is dominant, a capital letter is given to it. In this case, a T is for tall. When the allele is recessive, a lowercase letter is given to the trait (t for short). Now, with the above information, what are the results of the offspring, if one parent is TT (tall) and the other is tt (short)?
Note: When both parents contribute identical alleles for a trait to an offspring (TT or tt), the offspring is homozygous for that trait; while parents contributing different alleles to an offspring (Tt), the offspring is said to be heterozygous for that trait. The genetic composition (such as TT, tt or Tt) of an offspring is known as Genotype.
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