Question

What is the chromosome theory of inheritance? What are genes, alleles, and genotypes? What are monohybrid cross, dihybrid cross, and reciprocal cross?

Answer 1

Chromosome theory of inheritance :

The Chromosome theory of inheritance was postulated by Sutton & Boveri independently in 1902 , this theory states that genes are located on chromosome. The behavious of chromosome during meiosis & fertilization accounts for inheritance patterns. It is chromosome and not genes that undergo segregation & independent assortmrnt during meiosis.

Genes: Scientifically, genes are parts of DNA which produces RNA & thereby protein

Mendel persumed that a chracter is determined by a pair of factors or determiners present in each cell of an individual, these are known as genes in modern genetics.

The structural & functional unit of heredity is called gene.

Alleles:

Alternative form of one gene is called allelomorph or alleles. They are present on the same locus of the homologous chromosome.

Genotypes: It is the gene complement or genetic constitution of an individual with regard to one or more character irrespective of whether the genes are expressed or not.

Monohybrid cross: It involves the study of inheritance of one pair of contrasting character.

Dihybrid cross; It involves the study of inheritance of two pairs of contrasting characters.

Reciprocal cross: The reciprocal cross involve two crosses concerning the same character but with reversed sexes.