explain why there is greater emphasis on a molecular approach to understand life today than before?
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Answer:
Explanation:
In 1865, Gregor Mendel discovered the laws of heritability and turned biology into an exact science, finally on a par with physics and chemistry. Although the scientific community did not immediately realize the importance of his discovery—it had to be 'rediscovered' around 1900 by Correns, deVries and Tschermak—it came as a relief for a science in crisis. Many biologists in the twentieth century were tired of the purely descriptive nature of their science, with its systematic taxonomy and comparative studies. Charles Darwin's theory of evolution had already provided a first glimpse at the larger mechanisms at work in the living world. Scientists therefore felt that it was time to move from a descriptive science to one that unravels functional relationships—the annual 'Cold Spring Harbor Symposia on Quantitative Biology' was a clear testimonial to that desire. Mendel's four basic laws of genetics, formulated from meticulous experimentation, sparked a revolution in biology as they finally provided biologists with a rational basis to quantify observations and investigate cause–effect relationships.
To relate observed effects to the events that caused them is one of mankind's strong mental abilities. By understanding their relationship, it allows us to remember recurrent events and estimate their likelihood and reproducibility. This usually works well if a cause and its effect are linked by a short chain of events, but the challenge increases with complexity. Living organisms in their natural environment are probably the most complex entities to study, and causes and effects are not usually linked in single linear chains of causalities but rather in large multi-dimensional and interconnected meshworks. To unravel and understand these meshworks, it is therefore important first to study simple systems, in which the chains of near-causalities are relatively short and can be subdivided into single causalities, which are reproducible and thus comparable with what we call the 'laws of nature' in physics. Most of the important 'rules of nature', such as the 'genetic code', 'protein biosynthesis at ribosomes' or the 'operon' are examples of such chains. This new understanding has sparked a fresh debate about reductionist versus holistic approaches to biological research, which has implications for the public view and acceptance of biology and of its application in medicine and the economy.
The laws of genetics as formulated by Mendel were comparable with the basic laws of thermodynamics and therefore attracted many physicists to biological research. The German physicist Max Delbrück, for instance, who spent his earlier research career in astronomy and quantum physics, moved to biology in the late 1930s to study the basic rules of inheritance in the simplest organisms available, namely bacterial viruses (bacteriophages) and their hosts. As the political situation in Nazi Germany worsened, he left for the California Institute of Technology (Caltech; Pasadena, CA, USA), where he and Emory L. Ellis established the standard methods for this field (Ellis & Delbrück, 1939). The author of the present paper is no exception. Trained as a physicist around the middle of the last century, he changed to studying biophysics and biology. This followed the lead of his thesis advisor, Jean J. Weigle, who quit his position as a professor of experimental physics in Geneva, Switzerland, to join Max Delbrück's phage group at Caltech as a research fellow.
Living organisms in their natural environment are probably the most complex entities to study, and causes and effects are not usually linked in single linear chains of causalities...