The legacy goal and diversity in the 12th-grade biology syllabus is a very important topic that weighs heavily in competitive tests. This chapter describes the basic concepts of heritage and the ideas expressed by biologists.
In this chapter, students will learn genetic laws, partial rule, hereditary chromosomal theory, gender determination, genetic modification, Mendel genetic law, and much more. The concept of a heritage pattern was developed following Mendel’s work and his contributions to the field of genetics.
This chapter provides insight into the gist of modern biology – genetics:
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The difference in DNA between humans is called genetic variation. Genetic mutations, jumps, environmental changes, and other such factors lead to genetic variation. It is a result of the way certain genes are expressed.
Mendel conducts experiments with Garden pea in the back of his garden to determine genetics. In this case, he took 14 pea plants that actually breed seven separate seeds that had two opposite traits.
Mendel referred to the genes as “genes” passed on from one generation to another.
And the elements (genes) that encode the opposite sign were called “alleles”.
Based on his observations, Mendel issued three estate laws.
1. Rule of Law
In the case of heterozygote formation, one of the alleles dominates. Also, a prominent allele is shown in the phenotype. Thus, when homozygous tall with (TT) alleles are mixed with smaller plants (tt), all growing plants become taller and have a distinctive feature with the genotype Tt.
2. Genetic Classification Act
During gamete formation during meiosis, each allele separates. Therefore, the characters are transferred to the gametes without mixing. Also, heterozygotes produce different types of gametes while homozygous has only one type.
3. The Independent Diversity Act
Mendel proposed another set of rules based on the observations he made on the dihybrid crosses known as Mendel’s Law of Independent Assortment. Mendel’s specific rule states that “when two pairs of symbols are combined in a hybrid, the separation of one pair of letters is independent of each of the characters”.
In simple terms, this law describes the independent classification of genes. It means that the allele acquired by the offspring from the various components are obtained independently.
An easy way to understand this rule with the help of the Punette square when done with two pairs of genes during the stage of meiosis and egg production and pollen in the F1 generation of the RrYy plant.
Sutton and Boveri backed Mendel's views by claiming that they carried gene chromosomes. In their view: Two Homologous chromosomes with two genetic allele are found in these homologous pairs of chromosomes in the same area. The homologous pair splits through the process of gamete formation during meiosis. Chromosomes also differentiate, independently. During fertilization, the gamete converts, and the resulting offspring have a diploid no. chromosomes resembling a parent. Morgan's extensive work with Drosophila melanogaster or fruit flies provided experimental evidence to support the genetic chromosomal theory.
Henking became the first scientist to use X chromosomes and named the body 'X'. Chromosomes that determine the growth of sex cells in a young person are called sex chromosomes. Some chromosomes are called autosomes. When the male produces two different types of gametes. This is called male heterogamety. It occurs in many animals, such as humans, fruit flies, locusts, etc. In some animals, this happens to women. That is, women exhibit heterogamety. For example - birds.
Changes in DNA sequence lead to mutations. Possible changes are acquired from one generation to the next. Genetic modification alters the genotype and phenotype of an organism. Not all changes are dangerous. Some changes are made to adapt to the changing environment. Thus, it plays a key role in the evolution and evolution of species. But some changes are dangerous and can lead to genetic predisposition or disease. Includes removal, replacement, duplication, replacement, etc. DNA sequence. Some changes lead to cancer. A mutation that determines when a single DNA sequence occurs. Example- Sickle cell anaemia, in which the 6th codon of the odi-globin sequence code changes from GAG to GUG. Therefore, glutamine is replaced by Valine. Frameshift modification where the installation or removal of one or more pairs of bases into DNA occurs.