Textbook Question
What did the Watson–Crick model suggest about the replication of DNA?
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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 27b
A primitive eukaryote was discovered that displayed a unique nucleic acid as its genetic material. Analysis provided the following information:
A major hyperchromic shift is evident upon heating and monitoring UV absorption at 260 nm.
Verified step by step guidance1
Step 1: Understand the concept of a hyperchromic shift. In nucleic acids, a hyperchromic shift refers to an increase in UV absorbance at 260 nm when the double-stranded structure denatures into single strands upon heating. This is because single-stranded nucleic acids absorb more UV light than double-stranded forms.
Step 2: Recognize that the presence of a major hyperchromic shift upon heating suggests that the genetic material has a double-stranded structure that can denature, similar to DNA or double-stranded RNA.
Step 3: Consider the types of nucleic acids that exhibit hyperchromic shifts. Double-stranded DNA and double-stranded RNA both show this property, while single-stranded nucleic acids show less or no hyperchromic shift upon heating.
Step 4: Use the information about the hyperchromic shift to infer the nature of the nucleic acid. Since the primitive eukaryote's genetic material shows a major hyperchromic shift, it likely contains a double-stranded nucleic acid.
Step 5: To further characterize the nucleic acid, additional experiments such as enzymatic digestion, base composition analysis, or molecular weight determination could be performed to distinguish between DNA and RNA or identify any unique features.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Hyperchromic Shift
A hyperchromic shift refers to an increase in UV absorption at 260 nm when nucleic acids denature, indicating strand separation. This phenomenon is commonly used to study the melting behavior of DNA or RNA, as single strands absorb more UV light than double-stranded forms.
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Nucleic Acid Structure and Types
Nucleic acids, primarily DNA and RNA, differ in structure and function. DNA is typically double-stranded with deoxyribose sugar, while RNA is usually single-stranded with ribose. Understanding these differences helps interpret unusual genetic materials in organisms.
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UV Absorption of Nucleic Acids
Nucleic acids absorb UV light maximally at 260 nm due to their aromatic bases. Monitoring UV absorption changes during heating reveals information about nucleic acid stability and conformation, essential for identifying the nature of genetic material.
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Related Practice
Textbook Question
A genetics student was asked to draw the chemical structure of an adenine- and thymine-containing dinucleotide derived from DNA. The answer is shown here:
The student made more than six major errors. One of them is circled, numbered 1, and explained. Find five others. Circle them, number them 2 through 6, and briefly explain each in the manner of the example given.
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Textbook Question
A primitive eukaryote was discovered that displayed a unique nucleic acid as its genetic material. Analysis provided the following information:
The general X-ray diffraction pattern is similar to that of DNA, but with somewhat different dimensions and more irregularity.
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Textbook Question
A primitive eukaryote was discovered that displayed a unique nucleic acid as its genetic material. Analysis provided the following information:
Base-composition analysis reveals four bases in the following proportions: Adenine = 8%; Guanine = 37%; Xanthine = 37%; Hypoxanthine = 18%
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Textbook Question
A primitive eukaryote was discovered that displayed a unique nucleic acid as its genetic material. Analysis provided the following information:
About 75 percent of the sugars are deoxyribose, while 25 percent are ribose.
Postulate a model for the structure of this molecule that is consistent with the foregoing observations.
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Textbook Question
One of the most common spontaneous lesions that occurs in DNA under physiological conditions is the hydrolysis of the amino group of cytosine, converting the cytosine to uracil. What would be the effect on DNA structure of a uracil group replacing cytosine?
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