Introduction
Mendelian inheritance is a kind of biological inheritance that follows the theories first put forth by Gregor Mendel in 1865 and 1866, which were later rediscovered in 1900 by Hugo de Vries and Carl Correns and popularised by William Bateson.
Mendel conducted a series of systematic experiments that examined 7 unique characteristics (for example, flower color, seed color, and seed shape) each with two distinct traits (e.g. white and purple flowers). For each trait, he produced true-breeding lines. For instance, a line of plants might only produce white flowers, whereas another might only produce purple flowers. He was curious about specific conditions. Therefore, he performed another cross between two plants with distinct characteristics to observe the offspring’s final trait across three generations. He proposed three laws according to his observations and the Law of Segregation is one such rule used in studying the Mendelian inheritance of different colored and sized seeds of any plant.
Aim of the Study
To study Mendelian Inheritance using seeds of different colors and sizes of any plant.
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Necessary Material and Apparatus
- Samples of Pea seeds or any other plant
- Petri Dishes
- Tray
- Napkin
- Pen/Pencil
- Notebook.
Procedure
The Law of Segregation is the basis for studying the Mendelian Inheritance using different colors and sizes of any plant. This law is based on one of the benchmark scientific experiments in genetics, the Mendel Pea Plant Experiment. Mendel chose the pea plant for this experiment for its measurable characteristics, short life cycle, and feasibility in breeding. Therefore, it became easy for Mendel to collect the data and conduct the experiment.
The points discussed below are the required steps in the procedure for the aforementioned experiment −
- Collect 100-128 Pea seeds of different shapes, sizes, and colors.
- Place these seeds in an enamel tray.
- Sort out 64 round seeds and 64 wrinkled seeds in different Petri plates. Similarly, 64 green seeds and 64 yellow seeds can also be separated to study Mendelian inheritance.
- The F1 progeny are represented by one yellow and one green seed.
- Take one yellow and one green seed in a petri dish together until all the seeds from the previous two dishes are finished. As a result, 64 pairs of seeds will be formed in the F1 generation.
- Now, put 32 progenies (pair of yellow and green seeds) in one petri dish and the remaining 32 in another petri dish representing the F1 males and females.
- Mix both the Petri dishes well with the help of a pen or pencil so as to achieve a random pairing of the seeds.
- Keep three Petri dishes ready to place seeds for the F2 generation as there could be three possibilities of the gene in the F2 generation. Let us consider YY for the yellow seeds, yy for green seeds, and Yy for the heterozygous dominant yellow seeds.
- Mark each Petri dish according to the expected seed genotype.
- Ask your friends or anybody to randomly pick two seeds from the Petri plates with F1 progeny and sort them out.
- If two yellow seeds are being picked, then put them in the petri dish marked for YY genotype.
- When two green seeds are picked, put them in the petri dish marked for yy genotype.
- In the condition that when one yellow and one green seed are picked together, place them in the petri dish marked for Yy genotype.
- The abovementioned step helps in finding out the genotype of the seeds in the F2 generation.
- Now, observe the number of seeds carefully and note down their ratio.
Observation
Make a table that includes the characteristics of seeds, the total number of observations, the number of seeds with contrasting traits, and the ratio.
| Characteristics | Total Number of Seeds | Genotype (F2 Gen)[YY: Yy: yy] | Ratio of phenotypes (F2 Gen) |
|---|---|---|---|
| Seed color | 128 | 32:64:32Or1:2:1 | 3:1 |