Alfred Hershey was from Owosso, Michigan, and Martha Chase was from Braintree, Massachusetts; they conducted their landmark experiments at Cold Spring Harbor Laboratory in New York.
Who were Alfred Hershey and Martha Chase?
Alfred Hershey was an American bacteriologist and Martha Chase was his research assistant; together they designed the 1952 blender experiment that proved DNA, not protein, carries genetic information.
Hershey (1908–1997) earned his Ph.D. from Michigan State College and joined the Carnegie Institution’s Genetics Research Unit at Cold Spring Harbor before the famous experiment. Chase (1927–2003), a skilled lab technician, handled the day-to-day phage preparations and radioactivity measurements that made the results reliable. Their collaboration is often remembered as a classic example of how careful technique can upend an entire scientific paradigm—in this case, the long-held belief that proteins were the hereditary material. (Honestly, this is the best approach for proving DNA’s role.)
What did Hershey-Chase discover?
They discovered that DNA, not protein, is the hereditary material of bacteriophages; the phosphorus-32 label ended up inside infected bacteria, while the sulfur-35 label stayed outside.
Now, the 1952 experiment used T2 bacteriophages—viruses that infect *Escherichia coli*. Hershey and Chase labeled phage proteins with ³⁵S and phage DNA with ³²P. After infection, only the ³²P entered the bacterial cells, showing that the viral DNA carried the instructions for making new viruses. This result directly contradicted the then-dominant protein-centric view of heredity and set the stage for Watson and Crick’s DNA structure model three years later.
What did Griffith Avery Hershey and Chase do?
They collectively overturned the idea that proteins were the genetic material by demonstrating that DNA transfers hereditary information between generations.
Frederick Griffith’s 1928 “transforming principle” experiment first hinted that something could transfer between bacteria. Oswald Avery’s 1944 work with *Pneumococcus* bacteria then showed that purified DNA—by itself—could transform harmless bacteria into virulent ones. Hershey and Chase’s 1952 blender experiment provided the final, decisive proof using viral genetics. Together, these four scientists reshaped modern biology by shifting the spotlight from proteins to nucleic acids.
How did Hershey and Chase label DNA?
They labeled phage DNA with radioactive phosphorus-32 because phosphorus is abundant in DNA’s phosphate backbone but absent from proteins.
Here’s the thing: they grew T2 phages in bacterial cultures supplied with ³²P-labeled phosphate, letting the virus incorporate the isotope into newly synthesized DNA. A parallel culture was grown with ³⁵S-labeled sulfate to tag phage proteins. The clean separation of labels allowed them to track which part of the virus entered the host cell during infection. This clever labeling strategy was key to interpreting the blender experiment’s outcome.
Did Martha Chase get a Nobel Prize?
No; Alfred Hershey alone received the 1969 Nobel Prize in Physiology or Medicine for the discovery of the replication mechanism and genetic structure of viruses.
That said, historians and scientists have debated whether Chase’s exclusion reflected the Nobel Committee’s policies at the time or the specifics of the nomination process. Regardless, Chase remained active in research, later studying chromosome structure at Brooklyn College. The Hershey-Chase experiment is now widely cited as one of the most elegant demonstrations in biology, with Chase’s technical contributions increasingly recognized in retrospect.
Why did Hershey and Chase use a blender?
They used a kitchen-style Waring blender to shear off phage coats from infected bacteria without destroying the cells; conventional centrifuges spun too fast and would have ruptured the delicate *E. coli*.
After letting phages attach to bacteria, the team agitated the mixture in a blender. Gentle shearing released the empty phage shells (ghosts) into the supernatant, while the heavier, infected bacteria pelleted to the bottom. This separation let them measure where each radioactive label ended up—inside the bacteria with the DNA, outside with the protein coat. The blender became iconic, giving the experiment its nickname.
What would Hershey and Chase have concluded if both radioactive?
They would have concluded that the viral protein coat entered the bacteria because both ³²P and ³⁵S would have been found inside the cells.
Had that happened, the protein shell—not the DNA—would have carried the genetic instructions. Their actual result showed the opposite: only ³²P entered, pinpointing DNA as the hereditary molecule. In retrospect, the experiment’s power comes from its binary outcome—either DNA or protein must carry the genes, and the data spoke unambiguously for DNA.
What did Avery conclude caused transformation?
Oswald Avery concluded that DNA was the transforming factor; purified DNA from virulent bacteria could convert harmless bacteria into disease-causing forms.
Avery’s 1944 paper in *The Journal of Experimental Medicine* described a series of enzyme treatments that showed only DNase (an enzyme that degrades DNA) destroyed the transforming activity. This proved that DNA—not protein, RNA, or polysaccharides—was responsible for the change. Hershey and Chase’s later experiment extended Avery’s conclusion from bacteria to viruses, cementing DNA’s role across life’s domains.
What did Avery conclude?
Avery concluded that DNA transmits genetic information and that this molecule could carry heritable traits from one organism to another.
His work answered a decades-old question: what molecule carries the instructions for building a cell and passing traits to the next generation? By isolating the transforming principle and showing it behaved like genetic material, Avery laid the groundwork for Hershey and Chase’s viral experiment. Historians often call Avery’s paper “the first clear demonstration that genes are made of DNA.”
What was the conclusion of Griffith’s experiment?
Griffith concluded that a ‘transforming principle’ from heat-killed virulent bacteria could make harmless bacteria virulent.
In 1928, Griffith observed that mice injected with a mix of live rough (*R*) *Pneumococcus* and heat-killed smooth (*S*) bacteria died. Live smooth bacteria were recovered from the mice, indicating that something from the dead *S* strain had transformed the harmless *R* strain. Griffith didn’t identify the molecule, but his observation galvanized a search that culminated in Avery’s 1944 breakthrough.
How did Hershey and Chase show that DNA is passed to new phages in phage reproduction?
They showed that the ³²P-labeled DNA from parent phages ended up in newly assembled phage particles; ³⁵S-labeled protein did not.
After infection, progeny phages contained the ³²P marker, proving that DNA—not protein—was copied and packaged into new viral coats. This result closed the loop: the genetic material must be both inherited and expressed, and DNA fulfilled both roles. The experiment provided direct biochemical evidence for the “central dogma” of molecular biology.
How did the results of the Hershey-Chase experiment strengthen Avery’s conclusion?
The ³²P label inside bacteria matched Avery’s prediction that genes reside in DNA; the absence of ³⁵S inside confirmed that protein wasn’t the hereditary material.
Avery had shown that DNA could transform bacteria; Hershey and Chase showed that DNA entered cells during viral infection and directed the production of new viruses. This convergence across two very different systems—bacterial transformation and viral replication—made the case for DNA as the universal genetic material overwhelmingly strong. Together, the experiments shifted the field’s entire framework.
What are the 3 roles of DNA?
DNA serves as the genetic blueprint, the template for RNA synthesis, and the structural scaffold for chromosomes.
First, DNA stores and transmits hereditary information across generations. Second, it acts as a template for transcription, guiding the production of messenger, ribosomal, and transfer RNAs. Third, DNA’s supercoiling and protein interactions organize the genome into compact, functional chromosomes. These three roles—information storage, expression, and packaging—underpin all life processes from bacteria to humans.
Which bacteria killed the mice in Griffith’s experiment?
Live smooth (*S*) *Pneumococcus* bacteria killed the mice; these strains secrete a polysaccharide capsule that protects them from the host immune system.
Griffith’s classic experiment used two strains of *Streptococcus pneumoniae*: smooth (virulent, encapsulated) and rough (avirulent, unencapsulated). Heat-killed smooth bacteria alone did not kill mice, but when mixed with live rough bacteria, the rough strain was “transformed” into a smooth, lethal form. This transformation was the first clue that a chemical substance could carry genetic information.
Is carbon a DNA?
Carbon is not DNA, but it is a fundamental element in every DNA molecule; each deoxyribose sugar ring contains five carbon atoms.
DNA’s backbone is built from alternating sugar (deoxyribose) and phosphate groups. The sugar’s carbon atoms (numbered 1′ to 5′) form the ring structure that links to phosphate and to the nitrogenous bases (A, T, C, G). Without carbon’s four bonding sites, the sugar-phosphate backbone—and thus DNA itself—could not exist. In short, carbon is the scaffolding, not the finished structure.
Alex Chen is a senior tech writer and former IT support specialist with over a decade of experience troubleshooting everything from blue screens to printer jams. He lives in Portland, OR, where he spends his free time building custom PCs and wondering why printer drivers still don't work in 2026.