SOME ELEMENTARY HUMAN GENETICS
a. Heredity. With respect to both anatomy and physiology, offspring tend to
resemble their parents. This is due to the process known as heredity or inheritance.
Heredity depends upon the passage of materials called genes from one generation to
the next. Due to genes, all human beings resemble each other in general, but with
b. Genetic Control. The genes control the life processes of each body cell. In
an individual, each cell has identical genes. Overall, genes determine the range of
potentiality of an individual, and the environment develops it. For example, good
nutrition will help a person to attain his full body height and weight within the limits
determined by his genes.
HISTORY OF GENETICS
a. Over a hundred years ago, the Austrian monk Gregor Mendel began the
science of genetics by experimenting with successive generations of peas. He
originated the concepts of genes, dominance, and recessiveness. By choosing the
simplest and most straightforward situations, he set forth the basic principles of
inheritance. However, his work was not well known for many years.
b. With the turn of the century, the principles of genetics were "rediscovered,"
particularly by the Dutch biologist Hugo de Vries. In the following years, the principles
of genetics were further developed by the American, T. H. Morgan.
c. In 1944, Oswald T. Avery and his colleagues used bacterial studies to prove
that DNA was the genetic substance of chromosomes.
d. In 1954, Watson and Crick published the double helix model of DNA. (A
helix is a spiral form.)
e. Three Frenchmen, Jacob, Lwoff, and Monod, discovered how information is
transmitted from the genes to the sites of protein synthesis. This led to the "cracking" of
the genetic code, used to translate DNA patterns for the production of specific proteins.
DNA (deoxyribonucleic acid) is a large molecule consisting of two strands in a
double-helix arrangement. Along each strand are specific chemical elements called
nucleotides. Each gene consists of a portion of a strand, including a number of