Multiple Choice
The Avery, Macleod, and McCarty experiment in 1944 figured out what?
856
views
4
rank
7. DNA and Chromosome Structure
DNA as the Genetic Material
1:14 minutesProblem 1a
Textbook Question
How were scientists able to determine that DNA, and not some other molecule, serves as the genetic material in bacteria and bacteriophages?
Verified step by step guidance1
Scientists conducted experiments to determine the molecule responsible for genetic inheritance. One key experiment was Griffith's transformation experiment, which demonstrated that a 'transforming principle' could transfer genetic information between bacterial strains.
Avery, MacLeod, and McCarty expanded on Griffith's work by isolating the 'transforming principle' and showing that it was DNA. They treated bacterial extracts with enzymes that degrade proteins, RNA, and DNA, and found that only DNA degradation prevented transformation.
Hershey and Chase provided further evidence using bacteriophages (viruses that infect bacteria). They labeled DNA with radioactive phosphorus (32P) and proteins with radioactive sulfur (35S) to track which molecule entered bacterial cells during infection. Only the radioactive DNA was found inside the bacteria, confirming DNA as the genetic material.
The structure of DNA, as proposed by Watson and Crick, provided a molecular explanation for its role in heredity. The double-helix model showed how DNA could store genetic information and replicate accurately.
Techniques such as X-ray diffraction (used by Rosalind Franklin and Maurice Wilkins) and biochemical analysis were critical in determining the structure and function of DNA, further solidifying its role as the genetic material.
Verified video answer for a similar problem:This video solution was recommended by our tutors as helpful for the problem above
Video duration:
1mWas this helpful?
Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Experiments Demonstrating DNA as Genetic Material
Key experiments, such as those by Avery, MacLeod, and McCarty, demonstrated that DNA is the substance responsible for heredity. They showed that when DNA was extracted from pathogenic bacteria and introduced to non-pathogenic strains, the latter transformed into pathogenic forms, indicating that DNA carries genetic information.
Recommended video:
Guided course
09:32
History and Experiments
Structure of DNA
The double helix structure of DNA, proposed by Watson and Crick, is crucial for understanding how genetic information is stored and replicated. The arrangement of nucleotides in a specific sequence allows for the encoding of genetic instructions, which can be accurately copied during cell division.
Recommended video:
Guided course
06:25DNA Structure
Bacteriophages and the Hershey-Chase Experiment
The Hershey-Chase experiment provided strong evidence that DNA is the genetic material in bacteriophages. By using radioactive labeling, they demonstrated that only the DNA from the virus entered bacterial cells and directed the production of new viruses, while the protein coat remained outside, confirming DNA's role in heredity.
Recommended video:
Guided course
06:04Mapping Bacteriophages
9:32mWatch next
Master History and Experiments with a bite sized video explanation from Kylia
Start learningRelated Videos
Related Practice