The Cell Theory - Essay Example

The Cell Theory Introduction Cells are the basic unit of life. Its discovery are attributed to a number of biologists who have developed different postulates that would explain its existence. The discovery of cells and the different premises of cell theory from 17th and 19th century could also never been possible without the discovery of microscope. Thus, the discussion of a specific cell theory and the microscope would go altogether in this paper. According to Starr & Evers, the foundation of modern biology is grounded on the four generalizations that constitute the cell theory which includes the following: 1) Every living organism consists of one or more cells; 2) The cell is the structural and functional unit of all organisms. A cell is the smallest unit of life, individually alive even as a part of multicellular organism. 3) All living cells arise by division of preexisting cells; and 4) Cells contain hereditary material, which they pass to their offspring when they divide (47). The term ‘cell’ originated during the 17th century when Robert Hooke described the arrangement of the cell just like a compartment. Such observation was made possible because Hooke modified the first microscope built by Zacharias Janssen on 1590 (Roy, 169). Since Hooke had only observed a dead protoplast and microscopes at that time were primitive, majority of the microbiologists were not convinced that all living things are composed of cell. It was only in the 19th century that the formal study of cell theory developed (including cell biology and cell division) because of the advancement made in modern microscopes. Together with Hooke, Aristotle, Grew and Malpighi, Leeuwenhoek, H.J. Dutrochet, M.I. Schleiden and T. Schwann, R. Virchow, and Louis Pasteur have contributed to the development of cell theory. In this paper, we will focus on the cell theory made by M.I. Schleiden and T. Schwann. Cell Theory Made by M.I. Schleiden and T. Schwann At the beginning of the 19th century, Schleiden and Schwann outlined the basic features of cell theory. Schleiden found out that all plant cells have similar structure while Schwann noted that animal cells don’t have cell wall (Roy, 169). Their cell theories have also explained the nature of single-celled organisms called protozoa. The image below shows the cell that were examined by Schleiden and Schwann during the 19th century (refer to Figure 1.1.). Historical Context of Schleiden and Schwann’s Cell Theory Schleiden and Schwann’s Cell Theory started from the scientists’ strong refusal to accept the ‘Preformationists’ perspective. Preformationists state that organisms have pre-existing form and its characteristics are inherited from their previous cells (Cantor et al., 360). Instead, Schleiden, Schwann and the other scientists sorted to epigenesist – the belief that cells emerged anew and are influenced by the internal and external environment. (Figure 1.1.) They proposed that both plant and animal cells underwent the same processes and therefore, must fundamentally have generally set of characteristics. According to Schleiden, plant cells are formed by observing the following processes: 1) emergence of the granular substance inside the cell; 2) accumulation of the surrounding material to form the nucleus; 3) cell formation of the nucleus with the existence of surrounding membrane (Cantor et al., 361). Schleiden insisted that his theory must be considered as an absolute law as this laid out the foundations for the existence of protoplasm, nucleus, and cell wall – the basic structures of a plant cell. On the other note, Schwann further developed the study of Schleiden (this time, on animal subjects). He observed that the nucleus from animal cells emerged from ‘cytoblastema’, a dark granule. Subsequently, layers of substances started to accumulate until a new animal cell is formed. Schleiden-Schwann Cell Theory proposed that cells do not simply come from inheritance or pre-existence; rather, they came from the process of crystallization of both organic and inorganic substances. Their works were published and translated in 1847 with critics challenging the definition of cell, mode of cell origin, and nature of plant and animal tissues used in the study. However, the succeeding developments on the study of cell only proved the usefulness of Schleiden-Schwann Cell Theory for embryology. Cultural Context of Schleiden and Schwann’s Cell Theory The study of Schleiden and Schwann has changed the cultural view of the cell. Even today, the idea that the cell is the fundamental unit of life continues to change. Because of their studies, society was able to understand the nature of the cell and the different processes attached to it. From molecular medicine to plant biology, cell theory has grown sophistication towards genomics and bioinformatics. The conceptualization of Schleiden-Schwann Cell Theory has been helpful in materializing the basic foundation of cell theory into the big picture. Reactions of the Scientific Community Despite acceptance from other scientists, the Schleiden-Schwann Cell Theory had also raised eyebrows from the scientific community. Questions were raised with regards to the acceptance of the hypothesis as a theory and in other matters as well. Scientists highlighted the different issues of Schleiden-Schwann Cell Theory a follows (Rastogi, 145): existence and communication between cells cell command initiated by needs of an organism plurality of protoplasm in contrary to being a homogeneous substance existence of intercellular matrix which are not in cell theory different claims on the mechanism of cell formation by Schleiden and Schwann unit of cell as to function, heredity, and disease different physiological state of individual cells modifications of cell theory as merely doctrine or principle Reactions of Public The cell theory did not win the favor of those who believe in Preformationist perspective. Doctors, however, saw the dichotomy of human body and was encouraged to scrutinize dying individual to reveal the individual roles of cells and tissues. Thus, medicine has become a science of the individual. It has also changed the perspectives of the public from focusing on the pathology of the diseases to the individual cases to explain illness and health. Therefore, Schleiden-Schwann Cell Theory has led to an in-depth study of cells, alterations, and diseases in an atomistic view rather than only looking at holistic view. Examples in Popular Culture Works Cited Cantor, G.L. et al. Companion to the History of Modern Science. New York: Routledge Press, 1990. Online Book. Rastogi, V.B. Modern Biology (Vol. 1). New Delhi: Pitambar Publishing, 1997. Online Book. Roy, Shri Hermant. Comprehensive MCQs in Biology. Colorado: Golden Bell Press, 2005. Online Book. Starr Christine A. & Evers Lisa S. Biology Today and Tomorrow without Physiology. California: Brooks/Cole Cengage Learning Ltd., 2013. Online Book. Read More