(Study Material) Botany Study Material For AIPMT and State PMT Examination (Genetics: Introduction Concepts)
Study Material : Botany Study Material For AIPMT and State PMT Examination (Genetics: Introduction Concepts)
Inheritance Patterns
Mendel was the first scientist to develop a method for predicting the outcome of
inheritance patterns. He performed his work with pea plants, studying seven
traits: plant height, pod shape, pod color, seed shape, seed color, flower
color, and flower location. Pea plants pollinate themselves. Therefore, over
many generations, pea plants develop individuals that are homozygous for
particular characteristics. These populations are known as pure lines.
In his work, Mendel took pure-line pea plants and cross-pollinated them with
other pure-line pea plants. He called these plants the parent generation. When
Mendel crossed pure-line tall plants with pure-line short plants, he discovered
that all the plants resulting from this cross were tall. He called this
generation the F1 generation (first filial generation). Next, Mendel crossed the
offspring of the F1 generation tall plants among themselves to produce a new
generation called the F2 generation (second filial generation). Among the plants
in this generation, Mendel observed that three-fourths of the plants were tall
and one-fourth of the plants were short.
Mendel's laws of genetics
Mendel conducted similar experiments with the other pea plant traits. Over many
years, he formulated several principles that are known today as Mendel's laws of
genetics. His laws include the following:
1. Mendel's law of dominance: When an organism has two different alleles for a
trait, one allele dominates.
2. Mendel's law of segregation: During gamete formation by a diploid organism,
the pair of alleles for a particular trait separate, or segregate, during the
formation of gametes (as in meiosis).
3. Mendel's law of independent assortment: The members of a gene pair separate
from one another independent of the members of other gene pairs. (These
separations occur in the formation of gametes during meiosis.)
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