The following Topics and Sub-Topics are covered in this chapter and are available on MSVgo:
The following Topics and Sub-Topics are covered in this chapter and are available on MSVgo:
Genetics and evolution is an important chapter that studies the evolutionary changes that take place due to genetic inheritance.
What is genetics?
Genetics is the subject that deals with inheritance and variations of characters to offspring from parents. It includes the biological process and study of genomes and genes.
What is the meaning of genes?
Units of inheritance are called genes. It contains vital information that is required to express a particular trait in any organism. Genes that are slightly different forms of the same gene are called alleles.
Evolution
There are many theories regarding the origin of life on Earth and the evolution of biodiversity on Earth.
The gradual evolution of life forms has taken place on Earth over a period of years. Similarities and differences among organisms that existed before and that exist today are shown through comparative anatomy and morphology. When the same structure is developed due to adaptations to different needs in different directions by organisms, it is known as Homologous.
Evolutionary change is led by genetics and involves the study of the genome. The process through which the size and structure of genome change with time is known as genome evolution. Thus evolutionary genetics is the study of evolution and population genetics.
Darwin’s theory of Evolution
Charles Darwin proposed his theory of evolution in his book “On the origin of species by natural selection”.
According to Darwin’s theory of evolution, the built-in variations in a population’s characteristics enables some to outbreed others and survive in natural conditions. Thus, Darwin suggested that those who adapted to the natural conditions better leave more progeny than less endowed. These will thus survive more and are therefore selected by nature. Darwin called it natural selection and implied it was a mechanism of evolution.
The four important requirements, according to Darwin in natural selection, are:
The study of evolution proves that organisms that existed ages ago experienced significant changes, and life today is better on Earth due to these changes.
Evolution has led to the classification of primitive and advanced organisms. The biodiversity we see today is a result of evolution that took place over the course of years.
There are mainly four important mechanisms that contribute to change in the gene pool of the population and form mechanisms of evolution.
1) Mutation
The mutation results in alteration of DNA sequences and therefore results in changes in the genotype of an organism and the phenotype of an organism.
2) Gene Flow
The process of transfer of genes from one population to another is called gene flow. Gene flow is one of the major contributors to genetic variation when gene flow occurs due to natural processes in a place where the particular gene variation does not occur.
3) Genetic Drift
When there is a change in the allele frequency of a population as a matter of chance rather than natural selection, it is known as genetic drift. The impact of genetic drift is smaller in large populations and vice versa.
4) Natural Selection
When certain genetic qualities that are beneficial for survival are passed on to future generations, it is known as natural selection. Natural selection leads to evolutionary change in population.
Four significant aspects explain the mechanism of genome evolution, which are:
1) Gene Duplication
When a particular DNA region is duplicated, Gene duplication occurs. The reasons for Gene duplication are:
The deletion or addition of chromosomes is known as Aneuploidy. Polyploidy always consists of more than two sets of chromosomes.
2) Transposable elements
Transposable elements refer to a region in DNA that can be inserted anywhere in the genome by copying and pasting mechanisms.
3) Exon shuffling
New genes are formed as a result of exon shuffling. Thus a new gene is introduced in the genome as a result of two exons from different genes coming together. The coding part in the gene is known as Exon and is thus a part of gene expression.
4) Mutation
Alterations in the genome occur due to spontaneous mutation, and the nucleotide sequence creates a frameshift mutation in the genome.
Thus, genetics and evolution is the study of the branch of biology that explains the evolution of life and diversity on planet earth. Charles Darwin is considered to be the pioneer in the study of Evolution as this word was first mentioned in his book in 1859, which also described in detail the process of “Survival of the fittest”.
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