Textbook Question
How was it determined that the structure of DNA is a double helix with the two strands held together by hydrogen bonds formed between complementary nitrogenous bases?
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Ch. 9 - DNA Structure and Analysis
Klug10th EditionEssentials of GeneticsISBN: 9780135588789
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Table of contents
- Ch. 1 - Introduction to Genetics16
- Ch. 2 - Mitosis and Meiosis28
- Ch. 3 - Mendelian Genetics37
- Ch. 4 - Modification of Mendelian Ratios53
- Ch. 5 - Sex Determination and Sex Chromosomes32
- Ch. 6 - Chromosome Mutations: Variation in Number and Arrangement37
- Ch. 7 - Linkage and Chromosome Mapping in Eukaryotes36
- Ch. 8 - Genetic Analysis and Mapping in Bacteria and Bacteriophages24
- Ch. 9 - DNA Structure and Analysis38
- Ch. 10 - DNA Replication29
- Ch. 11 - Chromosome Structure and DNA Sequence Organization22
- Ch. 12 - The Genetic Code and Transcription36
- Ch. 13 - Translation and Proteins27
- Ch. 14 - Gene Mutation, DNA Repair, and Transposition34
- Ch. 15 - Regulation of Gene Expression in Bacteria22
- Ch. 16 - Regulation of Gene Expression in Eukaryotes37
- Ch. 17 - Recombinant DNA Technology27
- Ch. 18 - Genomics, Bioinformatics, and Proteomics30
- Ch. 19 - The Genetics of Cancer21
- Ch. 20 - Quantitative Genetics and Multifactorial Traits37
- Ch. 21 - Population and Evolutionary Genetics45
Chapter 9, Problem 1a
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
Understand the historical context: Scientists initially considered proteins as the genetic material because of their complexity and diversity, while DNA was thought to be too simple.
Examine the key experiment by Avery, MacLeod, and McCarty, who used purified components from heat-killed bacteria to transform non-virulent bacteria into virulent forms, showing that DNA was responsible for transformation.
Analyze the Hershey-Chase experiment, where bacteriophages were labeled with radioactive isotopes—phosphorus-32 to label DNA and sulfur-35 to label proteins—to track which molecule entered bacterial cells during infection.
Interpret the results of the Hershey-Chase experiment: the radioactive phosphorus (DNA) was found inside the bacteria, while the radioactive sulfur (protein) remained outside, indicating DNA carries genetic information.
Conclude that these experiments collectively demonstrated that DNA, not protein or other molecules, serves as the genetic material in bacteria and bacteriophages.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Hershey-Chase Experiment
This pivotal experiment used bacteriophages labeled with radioactive isotopes to distinguish DNA from protein. By tracking which molecule entered bacterial cells during infection, scientists demonstrated that DNA, not protein, carried genetic information.
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Mendel's Experiments
Role of Bacteriophages in Genetic Studies
Bacteriophages are viruses that infect bacteria, making them ideal for studying genetic material transfer. Their simple structure, composed mainly of DNA and protein, allowed researchers to isolate and test the function of each component in heredity.
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Chemical Composition and Function of DNA
DNA is composed of nucleotides forming a stable, information-rich molecule capable of replication and encoding genetic instructions. Its unique properties, unlike proteins, made it a strong candidate for the genetic material before experimental confirmation.
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Related Practice
Textbook Question
How do we know that G pairs with C and that A pairs with T as complementary base pairs are formed?
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Textbook Question
Most center around DNA and RNA and their role of serving as the genetic material. Write a short essay that contrasts these molecules, including a comparison of advantages conferred by their structure that each of them has over the other in serving in this role.
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