DEFINITIONS OF IMPORTANT TERMS OF GENETICS

1. Alleles – Alleles are the different alternate form of a particular gene. (OR) Alleles are the genes that govern variations of the same characteristic and that occupy corresponding loci on homologous chromosomes.

2. Back Cross – When a plant is crossed with any of its parents, it is known as Back Cross.

3. Cross – Cross is the mating between two individuals leading to the fusion of gametes.

4. Dihybrid Cross – Cross in which two pairs of contrasting or alternative trait is involved is known as Dihybrid Cross. Example: Tall plant with wrinkled seeds and Short plant with Round seeds (TTrr and ttRR) etc.

5. Dominant Alleles – Dominant alleles are the alleles which express themselves in both homozygous as well heterozygous condition.

6. F1/ First Filial Generation – The progeny (offspring) produced by the mating of individuals in the parental generation is known as F1 generation.

7. F2/ Second Filial Generation – The progeny (offspring) produced by the mating of individuals of F1 generation is termed as F2 generation. (OR) The subsequent generation produced by breeding of F offspring is termed as F2 generation.

8. Genes – Genes are the hereditary units. It is present on chromosomes.

9. Genetics – Genetics is a study of heredity.

10. Genotype – Genotype is the term used for Genetic constitution of plants. Example: TT, Tt, RR, rr etc.

11. Heterozygous – An individual that carries two different alleles for a given locus is said to be homozygous for that locus. Example: Aa, Tt, Rr etc.

12. Homozygous – An individual that carries two identical alleles for a given locus is said to be homozygous for that locus. Example: AA, aa, TT, tt, RR, rr etc.

13. Locus – It refers to the site a gene occupies in a chromosomes.

14. Monohybrid Cross – Cross in which only one pair of contrasting or alternative trait is involved is known as Monohybrid Cross. Example: Round and wrinkled (RR and rr); Tall and Short (TT and tt)

15. Phenotype – Phenotype is termed for the physical appearance of plants. Example: Tall, Dwarf etc.

16. Recessive Alleles – Recessive alleles are the alleles which are expressed only in the homozygous condition. Example: tt, rr, ss, aa etc.

17. Test Cross – When a plant is crossed with specifically recessive parents, it is called as test cross.

18. True breeding lines – True breeding lines are those plants which produces progeny exactly like themselves when allowed to self-pollinate.

 

Post Author: E-Biology

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