Terminology of Mendelian Genetics Gene: Gene is a segment of DNA that determines a biological character of an organism. It is also called the basic unit of heredity. Genome: The total genetic content of an organism is called genome. Allele or allelomorph: Allele or allelomorph is an alternate form of the same gene in which one is paternal and the other is maternal. For illustration, a gene for the plant height has two alleles - a gene for tallness (T) and a gene for dwarfness (t). Locus: The point on a chromosome where an allele is located is called locus (pl. loci). Homozygous: A diploid individual that carries two identical (similar) alleles of the same gene is known as homozygous individual or homozygote. For illustration, A pea plant having both the alleles of tallness (TT) is homozygous individual for tallness. Heterozygous: A diploid individual that has two different alleles of the same gene is called heterozygous individual or heterozygote. For example, an individual pea pl...
Genetic Materials Genetic material is the substance that is transmitted from one generation to the next generation to express its parental characters. The genetic material has following three main properties: It replicates and inherits to the offspring. It carries out all the information necessary for the function of a cell. It changes its sequence by mutation. Nucleic acids are the genetic materials in living organisms. In most of the organisms, DNA (deoxyribonucleic acid) is the genetic material except some viruses like retroviruses. Retroviruses have RNA (ribonucleic acid) as the genetic material. Watson and Crick showing the three dimensional model of DNA prepared using metal scraps “ FIO054: Figure 5.8c” by Rosenfeld Media, CC BY 2.0 Concept of Gene and Central Dogma of Molecular Biology Gene is a segment of DNA molecule which encodes a character of an organism. The term gene was coined by a Danish Geneticist, Wilhelm Johannsen in 1909 from the Greek word ‘genesis’ meaning ...