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Ch.4 - Nucleic Acids and the RNA World
Freeman - Biological Science 8th Edition
Freeman8th EditionBiological ScienceISBN: 9780138276263Not the one you use?Change textbook
All textbooksFreeman 8th EditionCh.4 - Nucleic Acids and the RNA WorldProblem 2
Chapter 4, Problem 2

What determines the primary structure of a DNA molecule?
a. Stem-and-loop configuration
b. Complementary base pairing
c. Deoxyribonucleotide sequence
d. Hydrophobic interactions and hydrogen bonding

Verified step by step guidance
1
Understand that the primary structure of a DNA molecule refers to the linear sequence of nucleotides.
Recognize that nucleotides in DNA are composed of a sugar (deoxyribose), a phosphate group, and a nitrogenous base.
Identify that the sequence of deoxyribonucleotides, which includes adenine (A), thymine (T), cytosine (C), and guanine (G), determines the primary structure of DNA.
Note that complementary base pairing (b) and hydrogen bonding (d) are involved in the secondary structure, not the primary structure.
Conclude that the correct answer is the deoxyribonucleotide sequence (c), as it directly specifies the order of bases in the DNA strand.

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Key Concepts

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

Deoxyribonucleotide Sequence

The primary structure of a DNA molecule is determined by its deoxyribonucleotide sequence. This sequence is the specific order of nucleotides, which are the building blocks of DNA, consisting of a sugar, a phosphate group, and a nitrogenous base. The sequence of these bases (adenine, thymine, cytosine, and guanine) encodes genetic information.
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Components of Dideoxy Sequencing

Complementary Base Pairing

Complementary base pairing is a fundamental principle of DNA structure where adenine pairs with thymine and cytosine pairs with guanine. This pairing is crucial for the double helix structure of DNA and ensures accurate replication and transcription processes. However, it is not the primary determinant of the DNA's primary structure, which is the linear sequence of nucleotides.
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Bases

Hydrogen Bonding

Hydrogen bonding occurs between complementary bases in the DNA double helix, stabilizing its structure. While these interactions are essential for maintaining the double-stranded form of DNA, they do not determine the primary structure. The primary structure is solely defined by the linear sequence of nucleotides, not by the interactions between them.
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Related Practice
Textbook Question

What are the four nitrogenous bases found in RNA?

a. Cytosine, guanine, thymine, uracil (C, G, T, U)

b. Adenine, cytosine, guanine, thymine (A, C, G, T)

c. Adenine, cytosine, guanine, uracil (A, C, G, U)

d. Alanine, cysteine, glycine, threonine (A, C, G, T)

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Textbook Question

Evaluate the following statements related to the synthesis of nucleic acids. Select True or False for each statement.

T/F Ribonucleotides are added to the 3′ end of a DNA strand.

T/F Polymerization of nucleic acids occurs by the formation of phosphodiester bonds.

T/F Complementary pairing between sugars is required for copying nucleic acids.

T/F Strands in a double helix are synthesized in an antiparallel orientation.

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Textbook Question

Single strands of nucleic acids are directional, meaning that there are two different ends. What functional groups define the two different ends of a strand?

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Textbook Question

What is responsible for the increased stability of DNA compared to RNA?

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