Francis Crick: Renegade Genius

“Francis Crick will be remembered as one of the most brilliant and influential scientists of all time,” remarked Richard A. Murphy, president and CEO of the Salk Institute. “He will be missed as a gentleman, a role model, and a person who has contributed so much to our understanding of biology and the health of mankind."

We examine this significant turning point in our knowledge of the building block of life, which has been over 70 years since Watson and Crick postulated the structure of DNA.

The historic paper that originally outlined the structure of DNA is celebrating its 70th anniversary this April. Although Rosalind Franklin's well-known photograph (number 51) greatly aided James Watson and Francis Crick in their initial descriptions of the double helix, why was knowledge of the structure of DNA so important?

Three takeaways:

1. The double helix

The physical structure of the DNA molecule was characterized by Watson and Crick as having "two helical chains each coiled around the same axis."

Perhaps the most well-known aspect of the discovery is the double helical structure of DNA. Another reality, however, is that complementary base pairs connect these two chains. This helps explain how a DNA molecule can accurately encode and duplicate genetic information.

2. The replication of DNA

Watson and Crick found that a DNA sequence may be reliably duplicated when cells divide by demonstrating that a DNA strand is made up of two chains and that DNA bases always pair predictably.

It has not missed our notice that the particular coupling we have hypothesized immediately offers a potential copying mechanism for the genetic material, the authors said in their research.

3. A sequence is formed by DNA

After demonstrating that DNA is made up of chains of base pairs, the notion that DNA has "sequence" was proposed. Without initially knowing the structure of DNA, others would not have been able to realize that a sequence of nucleotide bases could encode genetic information, even though this was never indicated in Watson & Crick's study.

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One of the most significant discoveries was the double helix. However, acknowledgment must also be given to the several other scientists whose research influenced Watson, Crick, and their peers. Here are only a few of them.

1. The discovery of DNA

Friedrich Miescher, a Swiss scientist, isolated DNA for the first time in 1869. He gave it the term "nuclein" after realizing that it was distinct from proteins.

The structure of individual DNA and RNA bases was later found in the early 20th century by the Russian scientist Phoebus Levene.

2. DNA makes up genes.

Oswald Avery, a Canadian American microbiologist, demonstrated the connection between genes and DNA in a 1944 paper. He observed that when DNA was present, a particular kind of non-virulent bacterium turned virulent. It was previously thought that genetic information was somehow encoded in proteins; therefore, this was a big finding.

American biochemist Erwin Chargaff, who was born in Austria-Hungary, acknowledged the significance of Avery's discovery. He observed that the quantities of cytosine and guanine, as well as adenine and thymine bases, were constant. Watson and Crick's concept of base pairing was influenced by this constant base ratio.

Chargaff also showed that the ratios of cytosine to guanine and adenine to thymine varied among species. This implied that genetic variations have a molecular foundation.

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Why is the identification of DNA significant?

Many medical advancements have contributed to lower mortality and longer life expectancies, from the creation of groundbreaking transplant surgery to something as basic as the use of antiseptics prior to procedures.

But in the end, what factors can influence your vulnerability to specific illnesses?

Your genetic composition is a major component, but environmental circumstances also play a contribution. Understanding the human genome began with the initial discovery of DNA structure, which also set the stage for future priceless scientific investigations.

The structure of DNA was discovered as a result of the work of many scientists.

When one thinks about the 1953 discovery of DNA structure, two names typically come to mind: James Watson and Frances Crick. Nevertheless, the results and theories of many other scientists who merit credit served as the foundation for their conclusions.

It was Alexander Todd who discovered that repeating phosphate and deoxyribose groups made up DNA's backbone.

Erwin Chargaff also discovered that, in spite of significant variations in the actual number of bases among species, the ratios of A to T and G to C consistently stayed at a 1:1 ratio.

But perhaps most critically, X-ray crystallography was used by Rosalind Franklin and Maurice Wilkins to uncover the helical structure of DNA, which greatly aided Watson and Crick in reaching their ultimate findings.

What, then, did these discoveries all point to regarding the general structure of DNA? Maybe a three-chain helix?

In the 1930s, Pauling, a prominent physical scientist who had discovered the alpha helix, was convinced that DNA was a three-chain helix with phosphates in the core and bases (A, T, C, and G) facing outward. This looks ridiculous now.

The Double Helix is proposed by Watson and Crick.

However, Watson and Crick identified flaws in this suggested structure in their 1953 Nature report. Specifically, the atom and bond spacing suggested in this model didn't seem realistic, and the negatively charged phosphates next to the axis would resist one another.

Rather, they proposed a model that included the unique notion that pairs of purine-pyrimidine bases connected by hydrogen bonds hold the two chains together.

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What else about their model made it so special? They discovered that only certain combinations were possible. G & C and A & T were these. This was a particularly important discovery since it was possible to automatically identify the sequence of the other chain if the bases on one chain were known.

Naturally, this phenomenon offered a potential way for genetic material to be copied, as Watson and Crick quickly realized. In their second paper, which was soon published in Nature, they discussed the general implications of DNA structure in more detail.

Replication of DNA and Heredity

One of their most astounding discoveries was the realization that a lengthy DNA molecule might contain an enormous variety of base-pair sequence combinations. Therefore, it appeared that the genetic information was encoded by the base sequence.

Due to its capacity to explain DNA replication, this finding had a significant instant impact. Their model demonstrated that DNA was a pair of complementary templates.

Did they really "discover the secret of life," as they said they had? Not exactly. They were still unaware of the polynucleotide precursors, or the "building blocks" of DNA, and how the chains could unwind and split apart to permit replication. However, they had achieved a breakthrough in the fields of protein synthesis and genetic coding.

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The principle of heredity also became apparent as a result of this improved understanding of genetics, which filled in a significant gap in Darwin's theory of evolution.

It is now known that the process by which evolution took place was the transmission of mutations during subsequent replications, which resulted in heritable differences.

Discontinuous Variation in Qualitative

Our knowledge of Mendelian genetics, which is the foundation of phenotypic qualities when variation is caused by allelic differences at specific loci, was also expanded by Watson and Crick's discoveries in the 1800s. To put it another way, knowing the nature of genes allowed us to comprehend the basis of qualitative discontinuous variation, such as whether a fly would be born with smooth or jagged wings or whether a flower will be pink or blue.

Additionally, humans made it possible to develop DNA sequencing techniques—basically, a method of figuring out the order of bases—after we had figured out the structure of DNA.

Fred Sanger sequenced the first full gene from a bacteriophage in 1972, but it would take many more years to sequence human DNA.

Uses and Implications for Disease Prevention and Treatment

Seeing the genomes of microorganisms, particularly viruses, is invaluable, despite the apparent importance of just being able to read the human genome.

For example, examining the genome of the quickly changing HIV virus enables us to monitor how the virus changes in specific patients and adjust treatment accordingly. It can also assist us in determining the patterns of HIV transmission within a nation and determining the causes of pandemics.

In the long run, DNA sequencing is significant for modern medicine since it could help us maximize the effectiveness of our therapeutic medical interventions.

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Because specific alleles can indicate varying degrees of vulnerability to disease, personality problems, and pharmacological responses, it is also useful for lifestyle and reproductive decisions. It makes it possible to identify genetic illnesses right away, and it is very helpful to use diagnostic techniques like amniocentesis on in vitro embryos.

On a somewhat less medicinal note, genetic fingerprinting and forensics also make use of DNA sequencing. Gene therapy may one day be used to treat inherited illnesses like cystic fibrosis. Both deleted mutant copies and healthy copies of the genes may be introduced into cells during the process.

In what ways has the world changed since the discovery of DNA structure?

DNA's unique structure has even served as architectural inspiration for structures, and its discovery served as the foundation for all of the sophisticated genetic research methods and procedures we currently employ.

If not for Watson and Crick, how would science be today? Without a doubt, our scientific understanding would lag by decades. It seems unlikely, however, that it would have been long before someone else figured out the structure given the ongoing advancements in imaging techniques.

Although the exact date of Watson and Crick's discovery was February 28 at the Cavendish Laboratory in Cambridge, the first paper was published on April 25, which is National DNA Day.

The pair initially enthusiastically discussed their discovery with their classmates at the now-historic Eagle pub in the heart of Cambridge, just a short distance from the lecture halls where throngs of medical students attend- an unprecedented historic event in the history of science.