Francis Crick

In 1953, Dr. Francis Crick and James Watson discovered the structure of the DNA molecule. This is the molecule which we now know stores the genetic information for all life. Many scientists have claimed the discovery to be the single most important development in biology during the 20th century. Watson and Crick’s investigation into the nature of the genetic code and the passing of information from generation to generation has redefined the study of genetics. Also, it has basically created the science of molecular biology.

For their outstanding work, James Watson and Dr. Francis Crick were awarded the 1962 Nobel Prize. As a youth, Francis Crick attended Northhampton Grammar School . At the age of fourteen he entered Mill Hill School in North London. While there he gained a good education in chemistry, physics, and mathematics. Crick was later an undergraduate study at University College of London where he received a degree in physics in 1937. Crick continued on at University College doing graduate work in physics until his research was interrupted by World War II.

After the war, Crick found himself less interested in the field of physics. He found an interest in Erwin Schrodinger’s book What is Life? The Physical Aspect of the Living Cell. Crick was convinced that many of the fundamental problems of biology could be examined by using the precise concepts and methods of physics and chemistry. The main theory Crick wanted to challenge was that of vitalism. Vitalism was the idea that life processes were due to a vital principle which was not explained by the laws of science.

In the middle of the century many scientists still believed that the family of macromolecules called proteins contained the key to understanding the chemical basis of genetics. However, Crick remained unconvinced that proteins could hold the key to passing on genetic information. In 1951 Francis Crick met a young American on a postdoctoral fellowship by the name of James Watson. The two scientists discovered that they shared the opinion that DNA, not proteins, was the critical factor in passing on genetic information.

They both believed that by solving the structure of the DNA, it would lead to an explanation of the self-replication of genes. Crick and Watson’s work to understand what role DNA played in the replication of the gene required them to obtain information from many different sources. In 1944, Oswald Avery had discovered that purified DNA, not proteins, was the main carrier of genetic information. This historic discovery set the stage for Crick and Watson to investigate the role of DNA in the gene. Just like any other scientist, Crick and Watson followed their share of false ideas.

But what greatly helped these two scientists was their ability to freely criticize eachother without being offensive. One of the great pieces of work by Francis Crick is the three-dimensional model of the DNA molecule which he and Watson produced. The model exhibits the two sides of a flexible ladder coiled around a common center to form a double helix. Each outside of the ladder, also called the backbone, is constant throughout the molecule and repeats the phosphate-sugar bond over and over again.

Attached to the inside of the backbone at the sugar is part of the ladder’s rung. This variable part of the DNA molecule consists of one of the four bases adenine, guanine, thymine or cytosine. The sequence of these bases along the inside of the ladder determines the genetic message. The key to Crick and Watson’s discovery was the realization that because of its size, shape and chemical makeup, each base on one side of the ladder could pair by hydrogen bonds with only one other base on the other complementary side of the ladder.

This meant that the large adenine molecule could pair only with the smaller thymine and the large guanine molecule could pair with only smaller cytosine. Once this structure was grasped the mechanism for molecular replication was obvious. Each of the two strands of the double helix could, upon separation of the hydrogen bonds between the base pairs, serve as a template for the synthesis of a new complementary strand. These two new strands form to create two double helices. In 1953, Francis Crick received his Ph. D. from Cambridge University.

Following that he continued his study of the genetic code. By working with Watson, molecular biologist Sidney Brenner, physicist George Gamov and others, Crick showed how the sequence of four bases in DNA and RNA induced the creation of the sequence of twenty basic amino acids. This initial discovery is still being studied today. By the year of 1966, Crick felt that the foundation of molecular biology had been sufficiently outlined and it was now time for him to pursue other interests. Next, Crick turned his attention to embryology.

In 1976 he went to the Salk Institute in California for a sabbatical year from the Medical Research Council. The following year, he decided to make a career change from the MRC and moved to the Salk Institute to pursue his interest in the workings of the brain. As part of Crick’s work he investigated the complex topic of human dreams. This interested Crick because he wanted to know more about neural nets. He discovered that you cannot understand how the brain works by just figuring out how one neuron works. You must understand how groups of neurons interact and work together.

When you store too many memories they tend to get in eachother’s way. Crick realized that in sleep and REM maybe the brain was trying to separate memories which got confused because they were too alive. Because the kind of mixtures you get in neural nets are the sort of things you have in dreams, Crick believed this to be evidence of that. The study of the brain has come a long way, but there is still a lot to be learned. Today, Francis Crick is greatly respected for the valuable work he has done in the exploration of the brain.


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