Podcast
Questions and Answers
Which of the following best describes the arrangement of DNA strands in a double helix?
Which of the following best describes the arrangement of DNA strands in a double helix?
- Antiparallel, with one strand running 5' to 3' and the other 3' to 5' (correct)
- Antiparallel, with both strands running 5' to 3'
- Parallel, with both strands running in the 5' to 3' direction
- Parallel, with both strands running in the 3' to 5' direction
Nucleotides containing uracil (U) are found in DNA, while nucleotides containing thymine (T) are found in RNA.
Nucleotides containing uracil (U) are found in DNA, while nucleotides containing thymine (T) are found in RNA.
False (B)
What type of bond connects nucleotides in a nucleic acid polymer?
What type of bond connects nucleotides in a nucleic acid polymer?
phosphodiester bond
Adenine (A) and guanine (G) are classified as ______, which are derivatives with two aromatic rings.
Adenine (A) and guanine (G) are classified as ______, which are derivatives with two aromatic rings.
Match each nitrogenous base with its complementary base in DNA:
Match each nitrogenous base with its complementary base in DNA:
Which of the following is a key structural difference between DNA and RNA?
Which of the following is a key structural difference between DNA and RNA?
The sequence of nucleic acids is typically written in the 3'-to-5' direction.
The sequence of nucleic acids is typically written in the 3'-to-5' direction.
What is the name of the rules that describe the base pairing in DNA?
What is the name of the rules that describe the base pairing in DNA?
Eukaryotic DNA is complexed to protein cores known as ______ complexes.
Eukaryotic DNA is complexed to protein cores known as ______ complexes.
Match the following bases with their classification as either purine or pyrimidine:
Match the following bases with their classification as either purine or pyrimidine:
What contributes to the stability of the double helix structure of DNA?
What contributes to the stability of the double helix structure of DNA?
RNA molecules commonly exist as double helices, similar to DNA.
RNA molecules commonly exist as double helices, similar to DNA.
What is the distance (in Ångströms) between the backbones of a DNA double strand, according to Watson and Crick's model?
What is the distance (in Ångströms) between the backbones of a DNA double strand, according to Watson and Crick's model?
The base pairs ______ have three hydrogen bonds between them, making them more stable than A-T base pairs.
The base pairs ______ have three hydrogen bonds between them, making them more stable than A-T base pairs.
Match the form of DNA with its description
Match the form of DNA with its description
Which end of a nucleic acid polymer has a free 5'-OH group?
Which end of a nucleic acid polymer has a free 5'-OH group?
Deoxyribonucleotides (dNTPs) contain ribose sugars.
Deoxyribonucleotides (dNTPs) contain ribose sugars.
What is the significance of the major groove in B-form DNA?
What is the significance of the major groove in B-form DNA?
Cytosine, thymine, and uracil are ______ derivatives, each with one aromatic ring.
Cytosine, thymine, and uracil are ______ derivatives, each with one aromatic ring.
Match the following terms regarding the building blocks of nucleic acids
Match the following terms regarding the building blocks of nucleic acids
Flashcards
Nucleic acids
Nucleic acids
Polymers of nucleotides connected by phosphodiester bonds.
Nucleotide building blocks
Nucleotide building blocks
Aromatic bases and ribose sugar.
Deoxyribonucleotides (dNTP)
Deoxyribonucleotides (dNTP)
Building blocks containing deoxyribose.
Nucleotides (NTP)
Nucleotides (NTP)
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Purines
Purines
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Pyrimidines
Pyrimidines
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Deoxyribonucleic acid (DNA)
Deoxyribonucleic acid (DNA)
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Ribonucleic acid (RNA)
Ribonucleic acid (RNA)
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Directionality in nucleic acids
Directionality in nucleic acids
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5′-to-3′ Direction
5′-to-3′ Direction
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Complementary strand
Complementary strand
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Antiparallel fashion
Antiparallel fashion
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Base pair
Base pair
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Watson-Crick base pairing rules
Watson-Crick base pairing rules
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B-form DNA
B-form DNA
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Histone
Histone
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RNAs
RNAs
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Study Notes
- Nucleic acids are polymers of nucleotides linked by phosphodiester bonds
Nucleotide Triphosphates
- Nucleotide triphosphates, the building blocks of nucleic acids, are distinguished by their aromatic bases and ribose
- Deoxyribonucleotides (dNTP) contain deoxyribose (2'-H)
- Nucleotides (NTP) contain ribose
- Five aromatic bases in dNTP & NTP: Adenine (A), Guanine (G), Cytosine (C), Thymine (T), and Uracil (U)
- Adenine (A) and Guanine (G) are purine derivatives (two aromatic rings)
- Cytosine (C), Thymine (T), and Uracil (U) are pyrimidine derivatives (one aromatic ring)
Types of Nucleic Acids
- Deoxyribonucleic acid (DNA) is made of polymers of deoxyribonucleotides
- Ribonucleic acid (RNA) is made of polymers of ribose-containing nucleotides
- Base T is only found in DNA
- Base U is only found in RNA
Directionality
- Nucleic acid polymers have directionality due to phosphodiester bonds linking the 3'-OH of one nucleotide with the 5'-OH of another
- One end has a free 5'-OH (5' end)
- The other end has a free 3'-OH (3' end)
- Sequences are written in the 5'-to-3' direction
- Ribose and phosphate parts form the backbone
DNA Strands
- DNA strands form a duplex with a complementary strand, not existing as monomers
- Backbones are right-handed helices arranged antiparallel, with the 5' end of one strand close to the 3' end of its complement
- Base planes are perpendicular to the helical axis, forming base pairs
DNA Double Helix
- DNA forms a double helix if sequences are complementary: G pairs with C, and A pairs with T (Watson-Crick base pairing)
- The backbone of the double strand is 20 Å apart, allowing reproduction of the sequence from one strand
- H-bonds between base pairs stabilize the double helix, along with Van der Waals interactions (base stacking)
- GC base pairs are more stable than AT pairs due to three H-bonds versus two, respectively
DNA Conformations
- DNA can adopt A-form, B-form, and Z-form conformations
- B-form is the most common and stable, with minor and major grooves
- The major groove allows interactions between DNA-binding proteins and bases
- Eukaryotic DNA is complexed to histone complexes for compact storage in the nucleus
RNA
- RNAs do not usually form a double helix and have diverse conformations, enabling various biochemical roles, including acting as enzymes
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