Chromosomal Theory of Inheritance – Concept and Background

We explain what the chromosomal theory of inheritance formulated by Sutton and Boveri is. Also, how it is based on Mendel’s laws.

chromosomal theory of inheritance boveri sutton
The chromosomal theory of inheritance postulates that genes are on chromosomes.

What is the chromosome theory of inheritance?

The chromosomal theory of inheritance or Sutton and Boveri’s chromosome theory is the scientific explanation about the transmission of certain characters through the genetic code containing the living cell, which occurs between one generation of individuals and the next.

This theory It was developed by scientists Theodor Boveri and Walter Sutton in 1902. Despite the distance between them, Boveri (German, 1862-1915) and Sutton (American, 1877-1916) independently postulated the same conclusions from previously existing knowledge of heredity and cell function.

It was a debated and controversial theory until 1915, when experiments with flies Drosophila melanogaster by American scientist Thomas Hunt Morgan (1856-1945) fully confirmed them.

The chromosomal theory of inheritance studied the genes, that is, the DNA segments that encode specific proteins, also called “hereditary factors” in his studies on heredity Gregor Mendel (1822-1884). Specifically, postulated that genes are located within the cell’s chromosomes, located in turn within the cell nucleus.

The existence of chromosomes was already known and its replication during cell division was known, but from now on they became much better known: it was known that they come in homologous pairs, one from the mother and the other from the father, so reproductive cells or gametes must provide each individual with the exact half of the genetic material.

This theory allowed to understand why certain characters are inherited and others are not, that is, why one allele is transmitted and another is not, since they are independent of each other, as they are located on different chromosomes. For example, the chromosome that contains information about the sex of the individual is different from the chromosome that contains information about the color of their eyes, etc.

Mendel’s Laws

chromosomal theory of inheritance mendel
Mendel discovered that not all genetic information manifests itself.

The main antecedent of the chromosomal theory of inheritance is constituted by the studies of Gregor Mendel, who carried out a series of experiments and follow-ups among pea plants, managing to formulate the well-known Mendel’s Laws on inheritance in 1865.

Their experiences were instrumental in understanding how genetic traits are passed from one generation to the next. discovered that there are traits (genes) of two types: dominant (AA) or recessive (aa), depending on whether it is manifest in the individual or not, being in the latter case a carrier of the non-manifest gene.

Thus, Mendel proposed the existence of “pure” individuals (homozygous), whether dominant or recessive (AA or aa), and of other heterozygotes resulting from genetic mixing and transmission (Aa), for each specific hereditary trait.

This approach was the first human attempt to describe the laws that govern genetics, and despite the fact that its results were recognized much later, it is a revolutionary contribution for its time, the foundation of everything that would come later.