Describe DNA Structure and Components - Biology
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What is the name for a DNA nucleotide without its phosphate group?
What is the name for a DNA nucleotide without its phosphate group?
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Nucleoside. Base attached to sugar without the phosphate group.
Nucleoside. Base attached to sugar without the phosphate group.
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What type of bond attaches a nitrogenous base to the deoxyribose sugar?
What type of bond attaches a nitrogenous base to the deoxyribose sugar?
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Glycosidic bond. Links the base to the $1'$ carbon of the sugar.
Glycosidic bond. Links the base to the $1'$ carbon of the sugar.
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If a DNA molecule has $18%$ cytosine, what percentage is guanine?
If a DNA molecule has $18%$ cytosine, what percentage is guanine?
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$18%$. Base-pairing rules mean C = G, so both are $18%$.
$18%$. Base-pairing rules mean C = G, so both are $18%$.
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Which end of a DNA strand has a free hydroxyl group on the sugar?
Which end of a DNA strand has a free hydroxyl group on the sugar?
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The $3'$ end. This end has an unattached OH group on the sugar.
The $3'$ end. This end has an unattached OH group on the sugar.
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What are the two ends of a DNA strand called based on carbon numbering?
What are the two ends of a DNA strand called based on carbon numbering?
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$5'$ end and $3'$ end. Named for the carbon atoms in the deoxyribose sugar ring.
$5'$ end and $3'$ end. Named for the carbon atoms in the deoxyribose sugar ring.
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What term describes the two DNA strands running in opposite directions?
What term describes the two DNA strands running in opposite directions?
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Antiparallel. Strands run in opposite directions for proper base pairing.
Antiparallel. Strands run in opposite directions for proper base pairing.
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How many hydrogen bonds typically form between C and G in DNA?
How many hydrogen bonds typically form between C and G in DNA?
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3 hydrogen bonds. G-C pairs have more hydrogen bonds than A-T pairs.
3 hydrogen bonds. G-C pairs have more hydrogen bonds than A-T pairs.
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How many hydrogen bonds typically form between A and T in DNA?
How many hydrogen bonds typically form between A and T in DNA?
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2 hydrogen bonds. A-T pairs have fewer hydrogen bonds than G-C pairs.
2 hydrogen bonds. A-T pairs have fewer hydrogen bonds than G-C pairs.
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Which base is complementary to guanine (G) in DNA?
Which base is complementary to guanine (G) in DNA?
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Cytosine (C). C forms three hydrogen bonds with G in Watson-Crick pairing.
Cytosine (C). C forms three hydrogen bonds with G in Watson-Crick pairing.
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Which base is complementary to cytosine (C) in DNA?
Which base is complementary to cytosine (C) in DNA?
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Guanine (G). G forms three hydrogen bonds with C in Watson-Crick pairing.
Guanine (G). G forms three hydrogen bonds with C in Watson-Crick pairing.
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Which base is complementary to thymine (T) in DNA?
Which base is complementary to thymine (T) in DNA?
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Adenine (A). T forms two hydrogen bonds with A in Watson-Crick pairing.
Adenine (A). T forms two hydrogen bonds with A in Watson-Crick pairing.
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Which base is complementary to adenine (A) in DNA?
Which base is complementary to adenine (A) in DNA?
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Thymine (T). A purine pairs with a pyrimidine following base-pairing rules.
Thymine (T). A purine pairs with a pyrimidine following base-pairing rules.
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What base-pairing rule states which DNA bases pair together?
What base-pairing rule states which DNA bases pair together?
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A pairs with T; C pairs with G. Watson-Crick base pairing ensures complementary strand formation.
A pairs with T; C pairs with G. Watson-Crick base pairing ensures complementary strand formation.
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What type of bond forms between complementary bases across the two DNA strands?
What type of bond forms between complementary bases across the two DNA strands?
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Hydrogen bonds. Weak bonds that hold complementary base pairs together.
Hydrogen bonds. Weak bonds that hold complementary base pairs together.
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What type of bond links the sugar and phosphate to form the DNA backbone?
What type of bond links the sugar and phosphate to form the DNA backbone?
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Phosphodiester bond. Covalent bond connecting nucleotides to form the DNA backbone.
Phosphodiester bond. Covalent bond connecting nucleotides to form the DNA backbone.
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Which DNA bases are classified as pyrimidines?
Which DNA bases are classified as pyrimidines?
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Cytosine and thymine. Single-ring structures that are smaller than purines.
Cytosine and thymine. Single-ring structures that are smaller than purines.
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Which DNA component varies and encodes genetic information: the backbone or the base sequence?
Which DNA component varies and encodes genetic information: the backbone or the base sequence?
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The base sequence. Variable base sequence carries genetic information, not backbone.
The base sequence. Variable base sequence carries genetic information, not backbone.
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What does the abbreviation DNA stand for in biology?
What does the abbreviation DNA stand for in biology?
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Deoxyribonucleic acid. The full name of the molecule that stores genetic information.
Deoxyribonucleic acid. The full name of the molecule that stores genetic information.
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Identify the correct base pairing for the DNA sequence $\text{T-T-A-C}$ on the complementary strand.
Identify the correct base pairing for the DNA sequence $\text{T-T-A-C}$ on the complementary strand.
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$\text{A-A-T-G}$. Apply base-pairing rules: T pairs with A, C pairs with G.
$\text{A-A-T-G}$. Apply base-pairing rules: T pairs with A, C pairs with G.
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Identify the correct base pairing for the DNA triplet $\text{A-C-G}$ on the complementary strand.
Identify the correct base pairing for the DNA triplet $\text{A-C-G}$ on the complementary strand.
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$\text{T-G-C}$. Apply base-pairing rules: A pairs with T, C pairs with G.
$\text{T-G-C}$. Apply base-pairing rules: A pairs with T, C pairs with G.
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Which pairing keeps the DNA helix a consistent diameter: purine-purine, pyrimidine-pyrimidine, or purine-pyrimidine?
Which pairing keeps the DNA helix a consistent diameter: purine-purine, pyrimidine-pyrimidine, or purine-pyrimidine?
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Purine-pyrimidine. This pairing maintains uniform helix diameter and stability.
Purine-pyrimidine. This pairing maintains uniform helix diameter and stability.
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What is the name for a DNA nucleotide without its phosphate group?
What is the name for a DNA nucleotide without its phosphate group?
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Nucleoside. Base attached to sugar without the phosphate group.
Nucleoside. Base attached to sugar without the phosphate group.
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What structural feature of DNA helps explain why A pairs with T and C pairs with G?
What structural feature of DNA helps explain why A pairs with T and C pairs with G?
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Purine-pyrimidine pairing maintains uniform helix width. Large purine paired with small pyrimidine maintains constant width.
Purine-pyrimidine pairing maintains uniform helix width. Large purine paired with small pyrimidine maintains constant width.
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What term describes the specific order of bases along a DNA strand?
What term describes the specific order of bases along a DNA strand?
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Base sequence (nucleotide sequence). The linear arrangement of bases that encodes genetic information.
Base sequence (nucleotide sequence). The linear arrangement of bases that encodes genetic information.
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What is a DNA polynucleotide?
What is a DNA polynucleotide?
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A chain of nucleotides linked by phosphodiester bonds. Multiple nucleotides joined together form a DNA strand.
A chain of nucleotides linked by phosphodiester bonds. Multiple nucleotides joined together form a DNA strand.
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Which carbon atoms are connected by a phosphodiester bond in DNA?
Which carbon atoms are connected by a phosphodiester bond in DNA?
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Between the $3'$ OH of one sugar and the $5'$ phosphate of the next. Links the $3'$ OH of one sugar to the $5'$ phosphate of another.
Between the $3'$ OH of one sugar and the $5'$ phosphate of the next. Links the $3'$ OH of one sugar to the $5'$ phosphate of another.
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What type of bond attaches a nitrogenous base to the deoxyribose sugar?
What type of bond attaches a nitrogenous base to the deoxyribose sugar?
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Glycosidic bond. Links the base to the $1'$ carbon of the sugar.
Glycosidic bond. Links the base to the $1'$ carbon of the sugar.
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What is meant by the statement that DNA strands are antiparallel?
What is meant by the statement that DNA strands are antiparallel?
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One strand runs $5'\to 3'$ and the other runs $3'\to 5'$. Strands have opposite orientations for proper base pairing geometry.
One strand runs $5'\to 3'$ and the other runs $3'\to 5'$. Strands have opposite orientations for proper base pairing geometry.
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What is meant by the statement that DNA strands are complementary?
What is meant by the statement that DNA strands are complementary?
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Each base sequence determines the other by pairing rules. Base-pairing rules ensure one strand determines the other's sequence.
Each base sequence determines the other by pairing rules. Base-pairing rules ensure one strand determines the other's sequence.
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Where are the nitrogenous bases positioned in the DNA double helix?
Where are the nitrogenous bases positioned in the DNA double helix?
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On the interior, paired across the two strands. Bases stack in the center and pair across the double helix.
On the interior, paired across the two strands. Bases stack in the center and pair across the double helix.
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