Oswald Avery, Colin MacLeod, and Maclyn McCarty showed that DNA (not proteins) can transform the properties of cells, clarifying the chemical nature of genes. After he injected mice with R strain cells and, simultaneously, with heat-killed cells of the S strain, the mice developed pneumonia and died.

Frederick Griffith Discovers Bacterial Transformation Figure 1: R variant phenotypes.

The Hershey–Chase experiments were a series of experiments conducted in 1952 by Alfred Hershey and Martha Chase that helped to confirm that DNA is genetic material.

On 1 February 1944, the Journal of Experimental Medicine published one of the breakthrough discoveries of the 20th century: Oswald Avery (1877–1955), together with his colleagues Colin MacLeod (1909–1972) and Maclyn McCarty (1911–2005), reported that the transformation of pneumococcus bacteria from one type to another …

Hershey and Chase concluded that protein was not genetic material, and that DNA was genetic material. Unlike Avery’s experiments on bacterial transformations, the Hershey-Chase experiments were more widely and immediately accepted among scientists.

Avery moved to the Rockefeller Institute in 1913, where he focused most of his research for the next thirty-five years on a single species of pneumonia-creating bacteria, Diplococcus pneumoniae. There, he worked with scientists that were widely recognized as being among the elite in their fields, including Alphonse R.

and MacLyn McCarty 1944 No one had anything significant to say about what the transforming principle might be until 16 years later, in 1944 when Oswald Avery, Colin MacLeod and MacLynn McCarty demonstrated that the transforming principle was DNA.

DNA, deoxyribonucleic acid, is the genetic material in your cells. It was passed on to you from your parents and determines your characteristics. The discovery that DNA is the genetic material was another important milestone in molecular biology.

Molecular genetics emerged from the realization that DNA and RNA constitute the genetic material of all living organisms. (1) DNA, located in the cell nucleus, is made up of nucleotides that contain the bases adenine (A), thymine (T), guanine (G), and cytosine (C).

Key Concepts and Summary DNA serves two important cellular functions: It is the genetic material passed from parent to offspring and it serves as the information to direct and regulate the construction of the proteins necessary for the cell to perform all of its functions.

The capsid surrounds the virus and is composed of a finite number of protein subunits known as capsomeres, which usually associate with, or are found close to, the virion nucleic acid.

The capsomere is a subunit of the capsid, an outer covering of protein that protects the genetic material of a virus. Capsomeres self-assemble to form the capsid.

The protein coat (capsid) and the nucleic acid together are the nucleocapsid. “Virion” refers to the entire virus. In the case of an enveloped virus, the virion is the entire virus and the nucleocapsid is the capsid and nucleic acid, minus the envelope.

The amount and arrangement of the proteins and nucleic acid of viruses determine their size and shape. The nucleic acid and proteins of each class of viruses assemble themselves into a structure called a nucleoprotein, or nucleocapsid.

Eight percent of our DNA consists of remnants of ancient viruses, and another 40 percent is made up of repetitive strings of genetic letters that is also thought to have a viral origin.