Genetic Terminology
To understand genetics, it is necessary to use some Genetic terminology which are as follows –
1. Parent Generation
In genetic science, the plants which are used in the experiment of hybridization are called parent plants and the generation is called parent generation.
2. F1 Generation
The generation produced as a result of crossbreeding between two parents is called F1 generation. For example, by crossing between pure tall (TT) and pure dwarf (tt) plants, all plants in the F1 generation get hybrid tall (Tt).
Reasons for Mendel's Success - Genetics3. F2 Generation
The progeny produced by crossing between the members of F1 generation is called F2 generation. Crossing between hybrid tall (Tt) plants gives tall and dwarf plants in the ratio of 3 : 1 phenotype and 1: 2 : 1 genotype in F2 generation.
4. Gene
Located on chromosome D.N.A. The part of the molecule that carries the genetic characteristics is called a gene. Gene is called the basic unit of genetics. Mendel did not use the word gene but used the word factor. For example, the length of a plant.
5. Genome
The complete set of haploid chromosomes which are passed from one generation to another in the form of a unit or gamete is called genome. It is mainly represented by the n chromosome.
6. Genotype
The genetic performance of a single trait is called a genotype. For example, the homozygous genotype (RR) and heterozygous genotype (Rr) of the red-flowered plant are.
7. Phenotype
The external or physical appearance of a trait is called a phenotype. It can be homozygous or heterozygous. For example, the plant being tall or dwarf.
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When two parents having different characteristics are crossed between them, the progeny produced is called hybrid progeny. For example, when a cross between pure tall and pure dwarf plants is done, then hybrid tall plants are obtained.
9. Hybridization
The process of artificial cross-pollination adopted between two genetically different animals to get the offspring of desired traits is called hybridization.
10. Acquired Characters
Characteristics produced after changes in the morphology or physiology of an organism due to the environment are called acquired traits. They are generally not inherited.
11. Dominant Character
When there is a cross between plants or organisms with comparable traits, the trait displayed in the first generation is called dominant trait. For example, the property of tallness (T) or red color (R) .
12. Recessive Character
When there is a cross between plants or organisms with comparable traits, the trait that is not shown in the first generation is called recessive trait. For example – dwarfism (t) or white color (r) property.
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Gene pairs with comparable traits are called alleles. They are located at the same locus of the chromosome. For example, tall (T) and dwarf (t) traits for the length of the plant etc.
14. Homozygous or True breeding
When both the genes of a pair of traits are the same, they are called homozygous plants. For example, both the dominant gene (TT) or both the recessive gene (Tt) are together for height.
15. Heterozygous or Hybrid
When both the genes of a pair of traits are unequal or different, they are called heterozygous plants. For example, tall and dwarf plant genes (Tt) are together.
16. Back Cross
When crossbreeds or crosses are done between the progeny of asexual offspring and their offspring, then this type of hybridization is called hybrid progenitor hybridization. For example, the process of getting the hybrid progeny (Tt) obtained in the F1 generation with any plant (dominant or ineffective) of the parent generation.
17. Test Cross
The process of crossbreeding between the F1 generation hybrid offspring and the recessive parent is called test hybridization. For example, the cross between the recessive parent (tt) of the parent generation (P) and the cross (Tt) of the F1 generation.
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