Important terms that are used in genetics are given below:
i. Chromosomes:
Filamentous bodies present in the nucleus, composed of chromatin material (DNA-RNA protein complex).
ii. Variation:
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Different characteristics produced in an individual of the same species by sexual reproduction.
iii. Gene:
A unit of inheritance which is passed from parents to the offsprings via chromosomes. Gene is the smallest unit capable of recombination or of mutation or of controlling the expression of a specific character.
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iv. Homologous Chromosomes:
A pair of corresponding chromosomes of the same size and shape, one from each parent.
v. Alleles:
Alleles are alternating molecular forms of a gene or a pair of matching genes affecting the same characteristic but in two different ways.
vi. Dominant Allele:
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A super ruling allele that masks any phenotypic effect of any recessive allele paired with it.
vii. Recessive Allele:
In heterozygous condition, an allele who cannot express fully or partially in presence of other allele.
viii. Homozygous Condition:
A condition in which a pair of homologous chromosomes carries identical (similar) alleles of a gene for a particular character.
ix. Heterozygous Condition:
A condition in which a pair of chromosomes carries non-identical (dissimilar) alleles for a particular character.
x. Character:
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Any heritable feature is called a character.
xi. Traits:
The alternative forms of a character are called traits.
xii. Genotype:
The genetic constitution of an organism.
xiii. Phenotype:
Externally visible expression of genes, which is an inherited feature in an individual’s appearance.
xiv. Mutation:
Sudden change in one or more genes or in the number and structure of chromosomes in the progeny that had not existed in the parents.