In The Gno

Genetics, the science of heredity, is a diverse field rich in many topics of study and research including genes and DNA, chromosomes, related diseases or conditions, and patterns of inheritance.  Roots of genetics can be traced back to the 1800s when an Austrian monk named Gregor Mendel first began studying inheritance patterns using garden-variety pea plants.  The results of his studies provided important groundwork for modern genetic science and are much of the reason why the science of genetics has prospered to date.  Mendel’s work provided basic laws establishing the rules for inheritance patterns and those laws, in turn, can be applied to many genetic situations including blood types and sex-linked traits.

Although many ideas on inheritance patterns pre-date Mendel, his work first demonstrated that (what we now know as genes) were the discrete, independently inherited units of heredity.  Mendel’s experimental organism of choice was the common garden pea, Pisum sativum.  He chose seven discrete pea plant characteristics:  Seed shape, seed color, flower color, pod shape, pod color, flower position, and stem height.  Each characteristic studied had two distinct forms, such as tall or short stem height, or smooth or wrinkled seed shape.  Mendel studied his plants for near eight years.

Mendel experimented with his pea plants by performing genetic crosses, usually monohybrid (involving only one trait) or dihybrid (involving two traits).  He experimented with true-breeding varieties, applied mathematics, and kept detailed results on his crosses.  Because of his diligence, use of math, and excellent choice of experimental organism, his studies eventually led to two important laws in genetics.

1.     Mendel’s Law of Segregation – each pair of alleles, or variants of genes, separate during gamete (egg and sperm) formation so that each gamete (egg and sperm) receives one member of a pair

2.     Mendel’s Law of Independent Assortment – during gamete (egg and sperm) formation, alleles (gene variants) in one gene pair segregate into gametes independently of other alleles (gene variants)

There is a lot of new vocabulary in the definition of these two laws, but one of the most important concepts is that Mendel’s experiments cements the idea that (1) we get one copy of a gene from one parent and another copy of the same gene from the other parent, and (2) human characteristics are inherited independently of other characteristics – for instance, hair color has nothing to do with eye color.

We will visit Mendel’s laws in more detail at a later date.  I’m Pyrimidiva, and I hope you have enjoyed our presentation on Mendelian Genetics.  For now, remember that what you “know” is not as important as what you “gno.”