Specific characterization of an organism is called a trait, which can be determined by genes, environment, and their interaction. The genetic contribution of these traits defines the organism’s genotype, and the physical appearance of genes is known as the phenotype. Skin colour, height, eye colour, diseases are the traits that get genetically inherited.
Genes
Genes are the functional and fundamental unit of the inheritance composed of deoxyribonucleic acid (DNA). Genes give and produce instruction of the cellular functions and the activity in the form of proteins. The number and the function of the human genes are studied by the Human Genome Project, which is working on determining the human genome sequence and identifying the genes. According to this project, 20,000 and 25,000 genes are estimated to be present in the human genome.
Alleles are the two variant forms of the genes acquired from each parent. Hence, the individual has two copies of genes. The tiny difference in the allele of the individual makes them unique and contributes to their exceptional physical features.
Genes were first studied by Gregor Mendel and were known as the discrete unit of inheritance that resulted in the appearance of physical characteristics. Further, the discovery of deoxyribonucleic acid and other molecules made understanding of genetic inheritance clear. From the experimentation and research, it was found that the genes are encoded in the DNA that makes up the chromosomes. The loci are the point where the genes are located on the chromosome.
Structure of gene
Genes are made up of many elements that are code for the information of cellular activity and functioning. The three major regions of the gene include the promoter region, coding region, and termination sequence.
The first region is the promoter sequence required by the gene for binding the transcription factors and RNA polymerase to initiate the transcription process. There may be more than one promoter present on a gene and are generally found in the mRNA. The eukaryotic’ promoter region is more complex than the prokaryotic genes.
Characteristics determined by Genes
In humans, there are 23 pairs or 46 chromosomes that define the feature or the trait called the genotype and the phenotype of the organism. Also, mutation can result in the formation and development of new genes and traits. The code or the protein produced by the genes defines their size, and the function of the cells is defined by the protein that is produced by the genes.
Genetic Inheritance
Individual parents have two copies of the genes that are inherited singly from them to the zygote or the offspring produced. Hence, the progeny contains one copy of the gene from each parent. The recombination and inheritance of the two copies of genes from each parent results in characteristics that make individuals different and unique.
Genetic traits like hair colour, blood group, eye colour, and disease get passed from the parent to the offspring and can have many forms. The inheritance pattern can be autosomal dominant, autosomal recessive, X-linked dominant, X-linked recessive, Y-linked, co-dominant and mitochondrial.
Function of genes
- The genes determine and influence the function of deoxyribonucleic acid and ribonucleic acid.
- Genes produce proteins essential for body function, activity and help in structural support.
- Genes also produce enzymes that aid in the chemical reaction and process of the body.
- Genes contain specific codes for the function or the instruction that defines the role of the particular gene in the body.
How do traits and genes determine the characteristics?
Traits are the specific characters that define the phenotype and the genotype of the organism. Traits are encoded and defined by the inheritance of the genes from the parent to the offspring. The total genetic material of the organism is called the genome and comprises many genes. The human genome project is the project that defines, identifies, maps, and sequences all the genes of the human genome.
The HGP project revealed that there are 20,500 genes in the human body that codes for specific traits and characteristics. The traits can be controlled by a single or multiple genes. If the trait is coded by more than one gene, then they are known as a polygenic trait. Body height and skin colour are polygenic traits that are influenced by more than one gene. Also, a single gene can determine a specific trait like the pigmented iris, ear lobes and many others.
Conclusion
Traits are the attributes and physical characteristics that are inherited from the parent to the offspring and are gene products. The genes are made up of DNA molecules and are present on the chromosomes in the cell. Each parent contributes a pair of genes to the progeny, making them unique and different from others. Humans have 20,000 to 25,000 genes that are coded for their characteristics. Single or multiple genes code many human traits.