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Ch. 1 - The Molecular Basis of Heredity, Variation, and Evolution
Sanders - Genetic Analysis: An Integrated Approach 3rd Edition
Sanders3rd EditionGenetic Analysis: An Integrated ApproachISBN: 9780135564172Not the one you use?Change textbook
Chapter 1, Problem 17

Identify two differences in chemical composition that distinguish DNA from RNA.

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1
Identify the sugar component in DNA and RNA: DNA contains deoxyribose, while RNA contains ribose.
Compare the nitrogenous bases present in DNA and RNA: DNA contains thymine, whereas RNA contains uracil.
Note that both DNA and RNA have adenine, cytosine, and guanine as common bases.
Understand that the presence of an -OH group on the 2' carbon of ribose in RNA makes it chemically distinct from the deoxyribose in DNA, which lacks this -OH group.
Recognize that these differences in sugar and base composition contribute to the structural and functional distinctions between DNA and RNA.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Nucleotide Structure

DNA and RNA are both nucleic acids composed of nucleotides, but their structures differ. DNA nucleotides contain deoxyribose sugar, while RNA nucleotides contain ribose sugar. This difference in sugar affects the stability and function of the molecules, with DNA being more stable and suited for long-term genetic storage.
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Nitrogenous Bases

Both DNA and RNA are made up of nitrogenous bases, but they differ in one of these bases. DNA contains adenine (A), thymine (T), cytosine (C), and guanine (G), whereas RNA contains adenine (A), uracil (U), cytosine (C), and guanine (G). The presence of uracil in RNA instead of thymine is crucial for RNA's role in protein synthesis.
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Strand Structure

DNA typically exists as a double-stranded helix, providing a stable structure for genetic information, while RNA is usually single-stranded. This difference in strand structure influences their functions; DNA serves as a long-term repository of genetic information, whereas RNA plays various roles in translating that information into proteins.
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