Genetic Mutations and the Foundations of Heredity

Genetic Problems and Mutations

There are several ways in which a gene may be defective and cause a failure in the process of creating a protein by the cell. In general, this is due to a change in the gene known as a mutation. The negative change or mutation can occur in three basic ways: one in which the order of the components of the gene has changed, another where components of the gene are lacking, and another where the complete gene is missing or does not exist on the chromosome.

To understand this, we use an analogy where a gene is a recipe and the components are the words of that recipe. Negative changes to the recipe would be such that the words are changed in order, words are missing, or whole sections are absent. Worse yet, the whole recipe could be missing, so that the result of the recipe with these changes will be flawed in many ways.

Causes That Affect Genes in a Population

The primary factors affecting genes within a population include: mutations, recombination, natural selection (a theory proposed by Charles Darwin), gene flow, and insulation.

The gene pool is the sum total of genotypes of all individuals in a determined population; i.e., they are the versions of the genes within a population. For example, in humans, some characteristics are visible to the naked eye while others are not.

Phenotypic and Genotypic Variation

• Phenotypic variation: These are observations of individuals within a population, such as weight, height, color, etc.
• Genotypic variation: In every generation, some individuals appear endowed with new features, which may be the product of recombination and/or mutations.

What Are Genes?

The development of genetics began in 1856 with the work of Gregor Mendel, an Austrian monk who worked with peas and published his findings in 1866. Mendel deciphered the foundations of heredity, but the results remained unknown for many years (De Donato, 1993). It was not until 1900 that three scientists—Hugo de Vries, Carl Correns, and Erich von Tschermak-Seysenegg—working independently, published their work to reveal and confirm the principles of Mendel.

Mendel states in his publication that phenotypic characteristics (the traits shown in an individual) are controlled by factors in each organism. These factors are now called genes.

Genes contain the information necessary to produce a complete organism and all its machinery and structure to keep it alive. Thus, genes control all aspects of the life of an organism, encoding products that are responsible for development, nutrition, reproduction, and more.