Genes are the basic unit of inheritance and they carry the genetic information from parents to offspring. The genes are located on chromosomes, which are long, thread-like structures present in the nucleus of a cell. The chromosomes are made up of DNA and proteins, and they contain the instructions necessary for the growth, development, and functioning of an organism.
The position of a gene on a chromosome is called a locus The position occupied by a gene or a factor on a chromosome is called a locus. Each chromosome has a specific number of loci where the genes are located. The locus is the physical location of the gene on the chromosome, and it is identified by its position relative to other genes on the same chromosome.
A gene, which affects the character of another gene, not located on a similar locus of the homologous chromosome is called an epistatic gene An epistatic gene is a gene that affects the expression of another gene, not located on the same locus of the homologous chromosome. The epistatic gene may either enhance or suppress the expression of the gene that it affects.
Assertion
A gene affecting the character of another gene not located on a similar locus of the homologous chromosome is called an epistatic gene. Reason: Epistatic gene hides the expression of an allele at a different locus. This assertion is true. An epistatic gene is a gene that affects the expression of another gene, not located on the same locus of the homologous chromosome. The epistatic gene may either enhance or suppress the expression of the gene that it affects. It hides the expression of an allele at a different locus, which means that the allele at a different locus is not expressed in the phenotype.
A gene that suppresses the effect of a gene not located on a similar locus of the homologous chromosomes is called as a suppressor gene A suppressor gene is a gene that suppresses the effect of another gene that is not located on the same locus of the homologous chromosomes. The suppressor gene may be present on the same chromosome or on a different chromosome.
Genes located on differential regions of the Y-chromosome are called Y-linked genes The Y chromosome is one of the two sex chromosomes in humans, with the other being the X chromosome. The genes located on the differential region of the Y chromosome are called Y-linked genes. These genes are only present in males, and they are responsible for male-specific traits.
Physical association of genes on a chromosome is called linkage The physical association of genes on a chromosome is called linkage. The genes that are located close together on the same chromosome are said to be linked, and they are inherited together as a unit. The degree of linkage between two genes is measured by the frequency of recombination between them during meiosis.
A sudden change in one or more genes, or in the number or in the structure of chromosomes is called a mutation A mutation is a sudden change in one or more genes, or in the number or structure of chromosomes. Mutations can occur spontaneously or be induced by exposure to mutagens such as chemicals, radiation, or viruses. Mutations can be beneficial, harmful, or have no effect on an organism.
The genes located at the same locus on homologous chromosomes are alleles The genes that are located at the same locus on homologous chromosomes are called alleles. Alleles are alternative forms of a gene that arise by mutation and are responsible for the variations in traits that exist within a population.
Linked Genes
Linked genes are the genes located on the same chromosome that are physically close to each other, and therefore, they tend to be inherited together as a unit. The physical association of genes on a chromosome is called linkage. The degree of linkage between genes depends on the distance between them. Genes that are located closer to each other on a chromosome have a higher chance of being inherited together, whereas genes that are located far apart on a chromosome have a lower chance of being inherited together.
Crossing Over
Although linked genes tend to be inherited together, they can be separated by a process called crossing over. During meiosis, when the homologous chromosomes pair up, they can exchange segments of DNA with each other, resulting in a recombination of the genes. This exchange of genetic material between homologous chromosomes is known as crossing over.
Crossover Frequency
The frequency of crossing over between two linked genes is related to the distance between them. If the two genes are located very close to each other on a chromosome, the probability of a crossover event happening between them is low, and they will tend to be inherited together. However, if the two genes are located far apart from each other on a chromosome, the probability of a crossover event happening between them is higher, and they will tend to be inherited independently of each other.
Mutations
Mutations are sudden changes that occur in the DNA sequence of a gene. These changes can either be a result of errors during DNA replication or from exposure to mutagens such as radiation or chemicals. Mutations can affect the structure or function of a protein encoded by a gene, which can lead to changes in the phenotype of an organism.
Conclusion
In conclusion, the position of a gene on a chromosome is called a locus. The locus of a gene determines its inheritance pattern and its relationship to other genes on the same chromosome. The interaction between genes located on the same chromosome can lead to the phenomenon of linkage and crossing over. Mutations can also occur within genes, which can lead to changes in an organism’s phenotype. The study of the position of genes on chromosomes is essential for understanding the inheritance patterns of genetic traits and the role of genes in the development and function of organisms.