Multiple Choice
Which of the following scientists discovered that DNA was the genetic material in viruses?
4. DNA, Chromosomes, and Genomes
DNA Discovery
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Which molecule did scientists believe was the source of genetic material first (before DNA)?
A
Protein
B
RNA
C
DNA
Verified step by step guidance1
Understand the historical context: In the early 20th century, scientists were trying to determine the molecule responsible for heredity. At that time, proteins were considered the most likely candidates due to their complexity and diversity.
Consider the properties of proteins: Proteins are made up of 20 different amino acids, allowing for a vast array of structures and functions. This complexity led scientists to believe that proteins could carry genetic information.
Examine the role of DNA and RNA: DNA and RNA are nucleic acids, which were known to be present in cells, but their role in heredity was not yet understood. DNA was thought to be too simple, with only four nucleotides, to carry complex genetic information.
Review key experiments: The Avery-MacLeod-McCarty experiment in 1944 and the Hershey-Chase experiment in 1952 provided evidence that DNA, not protein, was the genetic material. These experiments shifted the scientific consensus towards DNA.
Understand the role of RNA: Although DNA is the primary genetic material, RNA plays crucial roles in gene expression and regulation. The discovery of ribozymes and the RNA world hypothesis suggest that RNA may have been the original genetic material in early life forms.
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