MRC 1953, Manual

What is DNA?

DNA stands for Deoxy-ribo Nucleic* Acid, a molecule made of carbon, phosphorous, oxygen, nitrogen 

and hydrogen atoms. Nucleic acids, along with lipids (fat), proteins and carbohydrates (sugars), are the 

fundamental building blocks of life. If one were to look at it very closely, DNA looks like a spiral staircase or 

double helix made of two banisters (the backbone) with steps (the bases) linking the two. There are four 

bases (guanine, cytosine, adenine and thymine) - using different combinations they are used to store and 

transmit genetic information. 

Why is DNA important?

DNA is present in all forms of life: from plants and fungi to large mammals, through to bacteria and viruses. 

DNA contains all the information required to make up a living organism**. For example, DNA has instructions 

to determine your number of fingers, eye and hair colour. That is why DNA is often referred to as the “carrier” 

of the genetic information or life’s 'instruction manual'. 

What is Genetics?

Genetics is a branch of biology that studies heredity. Geneticists measure differences in the visible characteristics (traits) of live 

organisms and try to understand how they are transmitted to the next generation. This way, they learn about the function of different 

genes (the units of information in DNA), and how the traits relate to the genetic make-up of individuals. 

What can we learn by studying DNA?

Chemists first identified DNA in the late 19th century. In the early 20th century, scientists showed 

that it is essential for the transmission of hereditary traits from one generation to the next. LMB 

scientists in Cambridge built a model of DNA based on X-ray data collected by Rosalind Franklin and 

Raymond Gosling in London. This model showed that DNA forms a double-helix. The exciting part 

was that the model explained how the genetic information could be duplicated and transmitted to the 

next generation. The discovery of the structure of DNA marked the beginning of the era of molecular 

biology.
In 1962, James Watson, Francis Crick and Maurice Wilkins were awarded the Nobel Prize for 

physiology and medicine for their elucidation of the structure of DNA. This Lego model simplifies the 

key features of Watson and Crick's Model. It was designed by John Schollar at the National Centre 

for Biotechnology Education, whose support we gratefully acknowledge. 

* the term nucleic refers to the fact that DNA is found in the nucleus of cells.

**

in some viruses the genetic information is contained in a slightly different nucleic acid called RNA.

James Watson and Francis Crick

Francis Crick sketch 1953.