Last updated: April 17, 2019
Topic: ScienceBiology
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Abstract

Cell division and sexual reproduction was thoroughly studied in the late 1800’s with the emergence of modified microscopes which enabled biologists to further augment the study of cells. At that time, the transmission of hereditary traits from parents to offsprings was the primary emphasis of genetics. A myriad of theories and hypotheses were formulated yet failed to address the unanswered questions regarding heredity. Gregor Mendel, A european monk spent most of his time conducting experiments about genetics. His research paved the way for the further study of genetics. Geneticists owe Mendel the firm foundation of principles concerning heredity which is the cornerstone for all the studies about biology and its branches. His studies were eventually applied to humans and animals due to the fact that the mechanisims of heredity are similar for most complex life forms (O’Neil, 1997).

Mendel created principles such as: The Principle of Unit Characters states that individuals pass information on as individual traits, The Principle of Dominance states that some unit characters can mask the expression of others, The Principle of Segregation states that each unit character separates into a different sex cell, and The Principle of Independent Assortment states that genes segregate according to chance.  These principles were made formed through his experiment involving pea-plants produced principles that are used by geneticists today (O’Neil, 1997).

Mendelian Genetics

Gregor Mendel chose to conduct his experiment by using common garden pea plants as subjects. H e chose pea plants due to the fact that they can be easily grown in massive numbers and their reproduction can be manipulated as well. Pea plants are asexual plants in terms of reproducing which means that they can reproduce by self-pollination or through cross-pollination with other plant species. Mendel’s experiments showcased pure-bred plants along with their specific traits then selectively cross-pollinating each one of them. This enabled the study and its outcomes to be observed in the succeeding years. The firm basis for Mendel’s conclusions concering the nature of genetic inheritance was made possible through this pea plant experiment  (O’Neil, 1997).

Mendel was able to ascertain the specific traits that were manifested by the offspring without any pairing of a parent trait. Selective cross-breeding was used in this experiment. Colors of pea flowers varied, they were either purple of white and intermediate colors do not appear in the progeny of cross-pollinated pea plants. He determined and analyzed seven traits that are distinct which usually occurred in one of two forms (O’Neil, 1997). There traits are:

·         flower color is purple or white.

·         seed color is yellow or green.

·         flower position is axil or terminal.

·         pod shape is inflated or constricted.

·         stem length is long or short.

·         pod color is yellow or green.

·         seed shape is round or wrinkled.

Through this observation, the “Blending Theory” was formed, it was observed that such traits did not appear in offspring plants with intermediate forms and inherited traits blend from one generation to another. A theory by Charles Darwin known as “Pangenesis” proved similarly wrong and suggested that hereditary particles were caused and affected by matters which we do in the course of our lifetime. Such particles were transmitted through blood to the reproductive cells which eventually could be inherited by the succeeding generation. The very foundation and success of  Mendelian Genetics was based on the selection of suitable and appropriate characteristics which enabled Mendel to trace the inheritance of characteristices with two notable traits that genes carry: Dominant and Recessive (O’Neil, 1997).

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Reference

O’Neil,D. (1997). Mendel’s Genetics. Basic Principles of Genetics. Retrieved February10, 2008,             from  http://anthro.palomar.edu/mendel/mendel_1.htm