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Biology Flashcards: Describe Dna Structure And Components
Study Describe Dna Structure And Components in Biology with focused flashcards that help you recognize the idea, recall the key rule, and apply it in practice-style prompts.
Biology
Describe Dna Structure And Components
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What does the abbreviation DNA stand for in biology?
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ANSWER
Deoxyribonucleic acid. The full name of the molecule that stores genetic information.
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Flashcard 1: What does the abbreviation DNA stand for in biology?
Answer: Deoxyribonucleic acid. The full name of the molecule that stores genetic information.
Flashcard 2: What pentose sugar is found in DNA nucleotides?
Answer: Deoxyribose. The five-carbon sugar component of DNA nucleotides.
Flashcard 3: Identify the correct base pairing for the DNA sequence C-G-G-A on the complementary strand.
Answer: G-C-C-T. Apply base-pairing rules: C pairs with G, A pairs with T.
Flashcard 4: If a DNA molecule has 40% guanine, what percentage is cytosine?
Answer: 40%. Base-pairing rules mean C = G, so both are 40%.
Flashcard 5: What type of bond forms between complementary bases across the two DNA strands?
Answer: Hydrogen bonds. Weak bonds that hold complementary base pairs together.
Flashcard 6: What is the basic repeating subunit (monomer) of DNA?
Answer: Nucleotide. The building block that polymerizes to form the DNA chain.
Flashcard 7: What is the relationship between the number of C bases and G bases in double-stranded DNA?
Answer: The amount of C equals the amount of G. Chargaff's rule: C always equals G in double-stranded DNA.
Flashcard 8: Identify the correct base pairing for the DNA sequence C-G-G-A on the complementary strand.
Answer: G-C-C-T. Apply base-pairing rules: C pairs with G, A pairs with T.
Flashcard 9: Which base pair has two hydrogen bonds: A–T or C–G?
Answer: A–T. A-T forms two hydrogen bonds for weaker pairing.
Flashcard 10: What is the overall 3D shape of a DNA molecule called?
Answer: Double helix. Two antiparallel strands twisted into this characteristic spiral structure.
Flashcard 11: What pentose sugar is found in DNA nucleotides?
Answer: Deoxyribose. The five-carbon sugar component of DNA nucleotides.
Flashcard 12: What is a DNA polynucleotide?
Answer: A chain of nucleotides linked by phosphodiester bonds. Multiple nucleotides joined together form a DNA strand.
Flashcard 13: What are the two ends of a DNA strand called based on carbon numbering?
Answer: 5′ end and 3′ end. Named for the carbon atoms in the deoxyribose sugar ring.
Flashcard 14: Which pairing keeps the DNA helix a consistent diameter: purine-purine, pyrimidine-pyrimidine, or purine-pyrimidine?
Answer: Purine-pyrimidine. This pairing maintains uniform helix diameter and stability.
Flashcard 15: What type of bond links the sugar and phosphate to form the DNA backbone?
Answer: Phosphodiester bond. Covalent bond connecting nucleotides to form the DNA backbone.
Flashcard 16: If a DNA molecule has 30% adenine, what percentage is thymine?
Answer: 30%. Base-pairing rules mean A = T, so both are 30%.
Flashcard 17: What base-pairing rule states which DNA bases pair together?
Answer: A pairs with T; C pairs with G. Watson-Crick base pairing ensures complementary strand formation.
Flashcard 18: Which DNA bases are classified as pyrimidines?
Answer: Cytosine and thymine. Single-ring structures that are smaller than purines.
Flashcard 19: What is the relationship between the number of A bases and T bases in double-stranded DNA?
Answer: The amount of A equals the amount of T. Chargaff's rule: A always equals T in double-stranded DNA.
Flashcard 20: Which nitrogenous base is present in DNA but not in RNA?
Answer: Thymine. DNA contains thymine while RNA contains uracil instead.
Flashcard 21: What three components make up one DNA nucleotide?
Answer: Phosphate group, deoxyribose sugar, nitrogenous base. Three essential parts that together form each DNA building block.
Flashcard 22: What is a DNA polynucleotide?
Answer: A chain of nucleotides linked by phosphodiester bonds. Multiple nucleotides joined together form a DNA strand.
Flashcard 23: What structural feature of DNA helps explain why A pairs with T and C pairs with G?
Answer: Purine-pyrimidine pairing maintains uniform helix width. Large purine paired with small pyrimidine maintains constant width.
Flashcard 24: How many hydrogen bonds typically form between C and G in DNA?
Answer: 3 hydrogen bonds. G-C pairs have more hydrogen bonds than A-T pairs.
Flashcard 25: Where are the nitrogenous bases positioned in the DNA double helix?
Answer: On the interior, paired across the two strands. Bases stack in the center and pair across the double helix.
Flashcard 26: Identify the correct statement about strand direction: Are the two strands 5′→3′ in the same direction or opposite directions?
Answer: Opposite directions (antiparallel). Antiparallel orientation is essential for proper base pairing.
Flashcard 27: What is the relationship between the number of A bases and T bases in double-stranded DNA?
Answer: The amount of A equals the amount of T. Chargaff's rule: A always equals T in double-stranded DNA.
Flashcard 28: What term describes the specific order of bases along a DNA strand?
Answer: Base sequence (nucleotide sequence). The linear arrangement of bases that encodes genetic information.
Flashcard 29: What is the overall 3D shape of a DNA molecule called?
Answer: Double helix. Two antiparallel strands twisted into this characteristic spiral structure.
Flashcard 30: If a DNA molecule has 18% cytosine, what percentage is guanine?
Answer: 18%. Base-pairing rules mean C = G, so both are 18%.
Flashcard 31: What is the key difference between deoxyribose and ribose at the 2′ carbon?
Answer: Deoxyribose has H; ribose has OH at the 2′ carbon. DNA's sugar lacks the hydroxyl group that RNA's sugar has.
Flashcard 32: What term describes the weak interactions that allow DNA strands to separate during replication?
Answer: Hydrogen bonding between bases. Weak bonds allow strand separation during DNA processes.
Flashcard 33: What term describes the covalent linkage that makes the DNA backbone strong and stable?
Answer: Phosphodiester linkage. Strong covalent bonds provide structural stability to DNA.
Flashcard 34: How many hydrogen bonds typically form between C and G in DNA?
Answer: 3 hydrogen bonds. G-C pairs have more hydrogen bonds than A-T pairs.
Flashcard 35: What type of bond attaches a nitrogenous base to the deoxyribose sugar?
Answer: Glycosidic bond. Links the base to the 1′ carbon of the sugar.
Flashcard 36: Which base pair has three hydrogen bonds: A–T or C–G?
Answer: C–G. C-G forms three hydrogen bonds for stronger pairing.
Flashcard 37: Which base is complementary to thymine (T) in DNA?
Answer: Adenine (A). T forms two hydrogen bonds with A in Watson-Crick pairing.
Flashcard 38: Which base is complementary to adenine (A) in DNA?
Answer: Thymine (T). A purine pairs with a pyrimidine following base-pairing rules.
Flashcard 39: Which base is complementary to guanine (G) in DNA?
Answer: Cytosine (C). C forms three hydrogen bonds with G in Watson-Crick pairing.
Flashcard 40: What term describes the two DNA strands running in opposite directions?
Answer: Antiparallel. Strands run in opposite directions for proper base pairing.
Flashcard 41: Which end of a DNA strand has a free hydroxyl group on the sugar?
Answer: The 3′ end. This end has an unattached OH group on the sugar.
Flashcard 42: If a DNA molecule has 12% thymine, what percentage is cytosine?
Answer: 38%. T = A = 12%, so C = G = (100%−24%)/2=38%.
Flashcard 43: Which DNA bases are classified as purines?
Answer: Adenine and guanine. Double-ring structures that are larger than pyrimidines.
Flashcard 44: What is the relationship between the number of C bases and G bases in double-stranded DNA?
Answer: The amount of C equals the amount of G. Chargaff's rule: C always equals G in double-stranded DNA.
Flashcard 45: Which DNA component varies and encodes genetic information: the backbone or the base sequence?
Answer: The base sequence. Variable base sequence carries genetic information, not backbone.
Flashcard 46: Which end of a DNA strand has a free phosphate group?
Answer: The 5′ end. This end has an unattached phosphate group on the sugar.
Flashcard 47: Which DNA component varies and encodes genetic information: the backbone or the base sequence?
Answer: The base sequence. Variable base sequence carries genetic information, not backbone.
Flashcard 48: What is the name of the sugar-phosphate portion of DNA that forms the outside of the helix?
Answer: Sugar-phosphate backbone. Forms the structural framework on the outside of the helix.
Flashcard 49: Which four nitrogenous bases are found in DNA?
Answer: Adenine, thymine, cytosine, guanine. The four nitrogen-containing bases that encode genetic information.
Flashcard 50: What is meant by the statement that DNA strands are complementary?
Answer: Each base sequence determines the other by pairing rules. Base-pairing rules ensure one strand determines the other's sequence.
Flashcard 51: What base-pairing rule states which DNA bases pair together?
Answer: A pairs with T; C pairs with G. Watson-Crick base pairing ensures complementary strand formation.
Flashcard 52: If a DNA molecule has 18% cytosine, what percentage is guanine?
Answer: 18%. Base-pairing rules mean C = G, so both are 18%.
Flashcard 53: What is the name for a DNA nucleotide without its phosphate group?
Answer: Nucleoside. Base attached to sugar without the phosphate group.
Flashcard 54: What term describes the specific order of bases along a DNA strand?
Answer: Base sequence (nucleotide sequence). The linear arrangement of bases that encodes genetic information.
Flashcard 55: What three components make up one DNA nucleotide?
Answer: Phosphate group, deoxyribose sugar, nitrogenous base. Three essential parts that together form each DNA building block.
Flashcard 56: Which DNA bases are classified as purines?
Answer: Adenine and guanine. Double-ring structures that are larger than pyrimidines.
Flashcard 57: How many hydrogen bonds typically form between A and T in DNA?
Answer: 2 hydrogen bonds. A-T pairs have fewer hydrogen bonds than G-C pairs.
Flashcard 58: Which carbon atoms are connected by a phosphodiester bond in DNA?
Answer: 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.
Flashcard 59: What type of bond attaches a nitrogenous base to the deoxyribose sugar?
Answer: Glycosidic bond. Links the base to the 1′ carbon of the sugar.
Flashcard 60: Which end of a DNA strand has a free phosphate group?
Answer: The 5′ end. This end has an unattached phosphate group on the sugar.
Flashcard 61: Which base is complementary to cytosine (C) in DNA?
Answer: Guanine (G). G forms three hydrogen bonds with C in Watson-Crick pairing.
Flashcard 62: Which nitrogenous base is present in DNA but not in RNA?
Answer: Thymine. DNA contains thymine while RNA contains uracil instead.
Flashcard 63: Which base pair has two hydrogen bonds: A–T or C–G?
Answer: A–T. A-T forms two hydrogen bonds for weaker pairing.
Flashcard 64: Identify the correct base pairing for the DNA triplet A-C-G on the complementary strand.
Answer: T-G-C. Apply base-pairing rules: A pairs with T, C pairs with G.
Flashcard 65: Which base is complementary to thymine (T) in DNA?
Answer: Adenine (A). T forms two hydrogen bonds with A in Watson-Crick pairing.
Flashcard 66: What term describes the two DNA strands running in opposite directions?
Answer: Antiparallel. Strands run in opposite directions for proper base pairing.
Flashcard 67: If a DNA molecule has 40% guanine, what percentage is cytosine?
Answer: 40%. Base-pairing rules mean C = G, so both are 40%.
Flashcard 68: How many hydrogen bonds typically form between A and T in DNA?
Answer: 2 hydrogen bonds. A-T pairs have fewer hydrogen bonds than G-C pairs.
Flashcard 69: If a DNA molecule has 30% adenine, what percentage is thymine?
Answer: 30%. Base-pairing rules mean A = T, so both are 30%.
Flashcard 70: What is the name for a DNA nucleotide without its phosphate group?
Answer: Nucleoside. Base attached to sugar without the phosphate group.
Flashcard 71: Identify the correct base pairing for the DNA sequence T-T-A-C on the complementary strand.
Answer: A-A-T-G. Apply base-pairing rules: T pairs with A, C pairs with G.
Flashcard 72: Identify the correct statement about strand direction: Are the two strands 5′→3′ in the same direction or opposite directions?
Answer: Opposite directions (antiparallel). Antiparallel orientation is essential for proper base pairing.
Flashcard 73: If a DNA molecule has 12% thymine, what percentage is cytosine?
Answer: 38%. T = A = 12%, so C = G = (100%−24%)/2=38%.
Flashcard 74: What is meant by the statement that DNA strands are antiparallel?
Answer: One strand runs 5′→3′ and the other runs 3′→5′. Strands have opposite orientations for proper base pairing geometry.
Flashcard 75: Where are the nitrogenous bases positioned in the DNA double helix?
Answer: On the interior, paired across the two strands. Bases stack in the center and pair across the double helix.
Flashcard 76: Identify the correct base pairing for the DNA triplet A-C-G on the complementary strand.
Answer: T-G-C. Apply base-pairing rules: A pairs with T, C pairs with G.
Flashcard 77: What is meant by the statement that DNA strands are antiparallel?
Answer: One strand runs 5′→3′ and the other runs 3′→5′. Strands have opposite orientations for proper base pairing geometry.
Flashcard 78: Which carbon atoms are connected by a phosphodiester bond in DNA?
Answer: 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.
Flashcard 79: Identify the correct base pairing for the DNA sequence T-T-A-C on the complementary strand.
Answer: A-A-T-G. Apply base-pairing rules: T pairs with A, C pairs with G.
Flashcard 80: What does the abbreviation DNA stand for in biology?
Answer: Deoxyribonucleic acid. The full name of the molecule that stores genetic information.
Flashcard 81: Which base is complementary to adenine (A) in DNA?
Answer: Thymine (T). A purine pairs with a pyrimidine following base-pairing rules.
Flashcard 82: Which end of a DNA strand has a free hydroxyl group on the sugar?
Answer: The 3′ end. This end has an unattached OH group on the sugar.
Flashcard 83: What are the two ends of a DNA strand called based on carbon numbering?
Answer: 5′ end and 3′ end. Named for the carbon atoms in the deoxyribose sugar ring.
Flashcard 84: What is the key difference between deoxyribose and ribose at the 2′ carbon?
Answer: Deoxyribose has H; ribose has OH at the 2′ carbon. DNA's sugar lacks the hydroxyl group that RNA's sugar has.
Flashcard 85: Which DNA bases are classified as pyrimidines?
Answer: Cytosine and thymine. Single-ring structures that are smaller than purines.
Flashcard 86: What structural feature of DNA helps explain why A pairs with T and C pairs with G?
Answer: Purine-pyrimidine pairing maintains uniform helix width. Large purine paired with small pyrimidine maintains constant width.
Flashcard 87: Which four nitrogenous bases are found in DNA?
Answer: Adenine, thymine, cytosine, guanine. The four nitrogen-containing bases that encode genetic information.
Flashcard 88: Which base is complementary to cytosine (C) in DNA?
Answer: Guanine (G). G forms three hydrogen bonds with C in Watson-Crick pairing.
Flashcard 89: If a DNA molecule has 20% adenine, what percentage is guanine?
Answer: 30%. A = T = 20%, so C = G = (100%−40%)/2=30%.
Flashcard 90: What type of bond forms between complementary bases across the two DNA strands?
Answer: Hydrogen bonds. Weak bonds that hold complementary base pairs together.
Flashcard 91: Which base is complementary to guanine (G) in DNA?
Answer: Cytosine (C). C forms three hydrogen bonds with G in Watson-Crick pairing.
Flashcard 92: What is meant by the statement that DNA strands are complementary?
Answer: Each base sequence determines the other by pairing rules. Base-pairing rules ensure one strand determines the other's sequence.
Flashcard 93: Which pairing keeps the DNA helix a consistent diameter: purine-purine, pyrimidine-pyrimidine, or purine-pyrimidine?
Answer: Purine-pyrimidine. This pairing maintains uniform helix diameter and stability.
Flashcard 94: Which base pair has three hydrogen bonds: A–T or C–G?
Answer: C–G. C-G forms three hydrogen bonds for stronger pairing.
Flashcard 95: What term describes the weak interactions that allow DNA strands to separate during replication?
Answer: Hydrogen bonding between bases. Weak bonds allow strand separation during DNA processes.
Flashcard 96: What type of bond links the sugar and phosphate to form the DNA backbone?
Answer: Phosphodiester bond. Covalent bond connecting nucleotides to form the DNA backbone.
Flashcard 97: What is the basic repeating subunit (monomer) of DNA?
Answer: Nucleotide. The building block that polymerizes to form the DNA chain.
Flashcard 98: What is the name of the sugar-phosphate portion of DNA that forms the outside of the helix?
Answer: Sugar-phosphate backbone. Forms the structural framework on the outside of the helix.
Flashcard 99: What term describes the covalent linkage that makes the DNA backbone strong and stable?
Answer: Phosphodiester linkage. Strong covalent bonds provide structural stability to DNA.
Flashcard 100: If a DNA molecule has 20% adenine, what percentage is guanine?
Answer: 30%. A = T = 20%, so C = G = (100%−40%)/2=30%.