Genetics and Evolution

Genetics

Genetics is a branch of science which deals with the study of genes, genetic variations, and heredity in organisms. Genes are made up of DNA and are a kind of genetic guidance. These instructions are used to make molecules and to regulate the chemical reactions of life. We are transferred from parent to offspring.

Evolution

It is a process of hereditary changes in the population of organisms over several generations. The inherited traits are the expression of genes that are copied and transmitted to the offspring during reproduction. Heritable traits that are useful for survival and reproduction become more common, while harmful traits are uncommon.

Evolutionary Genetics

Evolutionary genetics is a study of how genetics leads to evolutionary changes. It involves studying the evolution of the structure of the genome. This is the sum of population genetics and evolution. Genome evolution is the process by which the size and structure of the genome change over time. The prokaryote genome develops through mutation, transduction, and horizontal gene transfer.

What is Evolutionary Genetics?

Evolutionary genetics is known as how genetic variation contributes to evolutionary changes. This includes the evolution of the genome structure, the genetic basis of adaptation and specification, and genetic changes in response to population selection. Evolutionary genetics is the sum of the genetics and evolution of the population.

Evolution of Structure of Genome

Genome evolution is defined as the process by which the genome changes its structure and size over time. The evolution of the prokaryotic genome happens by a number of methods-mutation, horizontal gene transfer, and transduction. The mutation is any permanent change in the body's nucleotide sequence. Horizontal gene transfer is a method of transferring genetic material from donor to recipient that is different from the vertical transfer (from parent to offspring).

Example of Genome Evolution - Bacteria

Transduction is another mode that takes evolution into the structure of the genome. It is defined as the transfer of genetic material via the virus to the cell. Figure 2 below: shows the evolutionary methods of prokaryotes. The eukaryotic genome is larger and more complex than the procaryotes. They 're evolving through sexual reproduction. This introduces a wide genetic diversity in eukaryotes compared to prokaryotes.

What are the different Mechanisms of Genome Evolution?

  • Gene Duplication- When a particular DNA region is duplicated. Gene duplication can occur through recombination, transposal, aneuploidy, polyploidy, and replication of the slippage (DNA replication error). Gene replication via recombination occurs when there is an irregular crossing at the time of meiosis. 

  • Transposable Elements – A region of DNA that can be inserted anywhere in the genome either by "cutting and paste mechanism" or by "copy and paste mechanism." For example, "Ty elements in Drosophila." The most common transposable element found in humans is the Alu sequence.

  • Mutation - Spontaneous mutations often cause changes in the genome. Mutations induce changes in the nucleotide sequence that induce the mutation of the frameshift, thereby altering the genome. It is also one of the processes of adaptation of the genome. Most common in procaryotes. 

  • Exon Shuffling - During exon shuffling, two exons of two different genes come together to form exon or repeat the same exon. This is the process by which new genes are being created. This adds a new gene to the genome. This plays an important function in the evolution of the genome.

Are Chimps Closer to Humans than Gorillas?

Earlier human species have been kept in the Hominidae family and apes have been kept in Ponguidae. This separation was based on certain features, such as the more advanced human brain and bipedal locomotion. Yet recent work has indicated that chimpanzees are nearest to the man followed by gorillas. The genetic material of primates and humans is closely linked to each other. The genetic material of chimpanzee and man differ by 1.2 percent, while the difference between gorillas and man is about 1.6 percent. This difference in genetic material confirms that chimpanzees are closer to humans than gorillas.

Terms to Remember 

  • Exon is the coding part of the gene, i.e. exon is a part of gene expression. The mature RNA messenger consists only of exons, which are later translated into protein. 

  •  Aneuploidy is a deletion or addition of chromosome number, which is normal human contains 46 chromosomes, but aneuploidy results in either 45 or 47 chromosomes. 

  •  Polyploidy consists of more than two sets of chromosomes. 

  • Transposition is a process in which the segment of the chromosome is transferred to a new position.

Mechanism of Genome Evolution

  • Duplication of Gene 

This is the duplication of a particular DNA region. It occurs by recombination, aneuploidy, transposition, polyploidy, and error in DNA replication. 

  • Transposable Components 

This refers to a DNA region that can be inserted anywhere in the genome. Ty elements in Drosophila, for example. Sequence Alu is the most common transposable element found in humans. 

  • Mutation  

Spontaneous mutations are responsible for genome changes. The nucleotide sequence changes resulting in a frameshift mutation that alters the genome. This is most common in prokaryotes.

  • Exon's Shuffling 

During this time, two exons from different genes come together. This process is created by new genes. As a result, a new gene is inserted in the genome.

FAQ (Frequently Asked Questions)

Q1 - Explain Genetics?

Ans – Genetics is a branch of science that deals with the transmission of information from parents to offspring. However, the definition does not attempt to give a holistic view of genetics. Let us make it work. So, genetics is a branch of science that answers why an elephant always gives birth to only a baby elephant and not to some other animal. Genetics is the reason why family members closely resemble each other. Genetics is the mystery behind species differences including human beings. Genetics lies behind the fact that all cells in the body can be metabolized as complex as a human body.

Q2 - Which Ape is Genetically Closest to Humans?

Ans - Chimpanzees are considered to be the closest living ape to the animal kingdom. The genome of the chimpanzee was sequenced by the researchers and it was found that they share 99 percent of DNA with humans, making them similar to each other.