Question

1. Грегора Иоганна Меделя называют отцом генетики, однако его вклад в биологи получил признание только после его смерти, в начале XX в. Г. Мендель разработал и положил в основу своих опытов гибридологический метод. Суть его заключается в скрещивании (гибридизации) организмов, отличающихся друг от друга по одному или нескольким признакам. Однако ученые (Дж. Госс, Огюстен Сажрэ, Ш. Ноден) проводили такие опыты и до Менделя. (а) Объясните, почему именно работы Менделя оказали наибольший вклад в генетику. Для опытов Мендель использовал разные сорта гороха, с пазушными цветками ис верхушечными цветками. Он наносил на рыльца цветков пыльцу с другого растения, все полученные гибриды были с пазушными цветками. (b) Определите генотипы и фенотипы гибридов F2 опыта Менделя, при условии, что они были получены путем самоопыления. Пропишите решение задачи полностью. Установив возможность предсказывать результаты скрещиваний по одной паре альтернативных признаков, Мендель перешел к изучению наследования двух пар таких признаков. (c) Были скрещены между собой горох с гладкими желтыми семенами и морщинистыми зелеными семенами, все полученные гибриды были гладкие и желтые. Определите генотип гибридов F2 при дигибридном скрещивании при самоопылении растений. Пропишите решение задачи полностью. Следует отметить, что в выборе экспериментального объекта Менделю кое в чем просто повезло: в наследовании отобранных им признаков не было ряда более сложных генетических особенностей, таких как неполное доминированиейли кодоминирование.​

Answer 1

Ответ:

(а) Потому что именно Мендель смог с матеиматической точностью описать генетику

(b) 3 жёлтых части - 75%

1 зелёная часть - 25% (3:1)

(с) 4 шт, АаВb

2 шт. ААВb

2 шт. АаВb

2 шт. Ааbb

2 шт ааВb

1 шт ААВВ

1 шт ААbb

1 шт ааВВ

1 шт ааbb

Итог: жёлтых особей 12, зеленых 4

это (3:1)

гладких семян 12, морщинистых 4

это (3:1)

Answer 2

Gregor Johann Mendel and his Contributions to Genetics

Gregor Johann Mendel is often referred to as the father of genetics. Although his contributions to biology were recognized only after his death in the early 20th century, Mendel developed and laid the foundation for his experiments using the hybridization method. This method involves crossing (hybridizing) organisms that differ from each other in one or more traits.

Mendel's work stood out and made the greatest contribution to genetics for several reasons:

(a) Experimental Approach: Mendel's experiments were meticulously designed and conducted using different varieties of pea plants with specific traits. He carefully controlled the pollination process by transferring pollen from one plant to another, ensuring that the resulting hybrids had specific traits. By doing so, Mendel was able to establish clear cause-and-effect relationships between the traits and their inheritance patterns.

(b) Laws of Inheritance: Through his experiments, Mendel formulated three fundamental laws of inheritance: the law of segregation, the law of independent assortment, and the law of dominance. These laws provided a framework for understanding how traits are passed from one generation to the next and laid the groundwork for modern genetics.

(c) Quantitative Analysis: Mendel's experiments involved counting and recording the number of plants with specific traits in each generation. He analyzed the data statistically, which was a novel approach at the time. This quantitative analysis allowed him to establish patterns and ratios in the inheritance of traits, providing further evidence for his laws of inheritance.

(d) Publication of Results: Mendel published his findings in 1866 in a scientific journal, "Experiments on Plant Hybridization." Although his work initially received little attention, it was rediscovered and recognized by other scientists in the early 20th century, leading to the establishment of Mendelian genetics as a fundamental concept in biology.

Overall, Mendel's meticulous experimental approach, formulation of fundamental laws of inheritance, quantitative analysis, and publication of his results were key factors that contributed to his significant impact on the field of genetics.

Genotypes and Phenotypes of F2 Hybrids in Mendel's Experiment

In Mendel's experiments, he crossed pea plants with different traits and observed the inheritance patterns in the offspring. Let's consider the F2 generation, which is the second filial generation resulting from the self-pollination of the F1 hybrids.

(a) Monohybrid Cross: In a monohybrid cross, Mendel crossed pea plants with round, yellow seeds (RRYY) with pea plants with wrinkled, green seeds (rryy). The F1 generation produced all round, yellow seeds (RrYy). When the F1 generation self-pollinated, the F2 generation showed a phenotypic ratio of 3:1 for round, yellow seeds to wrinkled, green seeds. The genotypic ratio was 1:2:1 for RRYY, RrYy, and rryy.

(b) Dihybrid Cross: In a dihybrid cross, Mendel crossed pea plants with round, yellow seeds (RRYY) with pea plants with wrinkled, green seeds (rryy). The F1 generation produced all round, yellow seeds (RrYy). When the F1 generation self-pollinated, the F2 generation showed a phenotypic ratio of 9:3:3:1. This means that 9 plants had round, yellow seeds, 3 plants had round, green seeds, 3 plants had wrinkled, yellow seeds, and 1 plant had wrinkled, green seeds. The genotypic ratio was 1:2:1:2:4:2:1:2:1 for RRYY, RRYy, RRyy, RrYY, RrYy, Rryy, rrYY, rrYy, and rryy.

These results demonstrated the principles of dominance, segregation, and independent assortment, which are the foundation of Mendelian genetics.

Conclusion

Gregor Mendel's work in the field of genetics made a significant contribution to the understanding of inheritance patterns and laid the foundation for modern genetics. His meticulous experimental approach, formulation of fundamental laws of inheritance, quantitative analysis, and publication of his results set the stage for further advancements in the field. By studying the inheritance of traits in pea plants, Mendel established the principles of dominance, segregation, and independent assortment, which continue to be fundamental concepts in genetics today.