Questions and Answers
Classify the description as pertaining to nucleosides, nucleotides, or both nucleosides and nucleotides.
What is the DNA sequence complementary to AGTC?
TCAG
Classify the statements as describing deoxyribonucleic acid (DNA) or ribonucleic acid (RNA).
What intermolecular force is responsible for holding the two strands of a DNA double helix together?
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What is a phosphodiester bond?
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Which DNA molecule has a lower percentage of G-C base pairs that stabilize DNA duplexes?
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How does the structure of DNA encode genetic information?
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What are the stabilizing factors that hold the two strands of DNA together in a double helix?
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In Watson-Crick base pairing in DNA, guanine pairs with?
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The phosphate groups are on the outside of the DNA double helix because they are charged and interact with the aqueous environment surrounding the DNA.
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What contribution did James Watson and Francis Crick make to our understanding of DNA?
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Choose the statement that explains why organisms use DNA as the central repository for genetic information.
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Match the structure names to the descriptions given.
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What is small nuclear RNA?
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What is ribosomal RNA?
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What is transfer RNA?
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What is small interfering RNA?
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What is messenger RNA?
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What is micro RNA?
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In bacteria, which two bases undergo methylation more often?
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What are the functions of nucleic acids?
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What are the functions of nucleotides?
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What are the components of a nucleotide?
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What are the components of a nucleoside?
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What is a phosphate group?
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What is a nitrogenous base?
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What are minor nucleosides in DNA?
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What is inosine?
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What is pseudouridine?
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What are prototropic tautomers?
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Where is keto-enol tautomerism common?
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Where does lactam-lactim tautomerism occur?
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What are polynucleotides?
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How are covalent bonds formed?
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Is the DNA backbone stable?
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Is the RNA backbone unstable?
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What is meant by linear polymers?
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What is hydrolysis of RNA?
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What are hydrogen bonding interactions?
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What is replication of genetic code?
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What is a beta-N-glycosidic bond?
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What is conformation around N-Glycosidic Bond?
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What is DNA denaturation?
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What are factors affecting DNA denaturation?
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What are applications of near-complementary hybrid in DNA and RNA?
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What is deamination?
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What is depurination?
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What is oxidative damage?
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What is chemical alkylation?
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What are molecular mechanisms of radiation-induced mutagenesis?
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Study Notes
Nucleic Acids: Structure and Function
- Nucleosides consist of a base and a pentose sugar, while nucleotides contain a phosphate group in addition to the base and sugar.
- DNA sequences can be complementary, with A pairing with T and C pairing with G.
- DNA is typically double-stranded and stable, while RNA is mostly single-stranded and more susceptible to hydrolysis.
Intermolecular Forces and Bonding
- Hydrogen bonds stabilize the DNA double helix structure.
- Phosphodiester bonds form the sugar-phosphate backbone, linking nucleotides covalently.
- Base stacking and hydrophobic interactions further stabilize DNA double helices.
DNA Structural Variations
- Sequence-dependent variations, such as hairpin, G-quadruplex, cruciform, and triplex structures, can influence DNA's function.
- Methylation of adenine and cytosine bases commonly occurs in bacteria, serving as an epigenetic marker.
Nucleic Acid Types and Functions
- Nucleic acids have various functional roles: DNA stores genetic information, mRNA transmits information, tRNA and rRNA are involved in protein synthesis.
- Minor nucleosides like inosine and pseudouridine play crucial roles in genetic code diversity and RNA stability.
Tautomerism and Stability
- Prototropic tautomers are structural isomers with differing proton locations; common in nucleotide bases.
- Keto-enol and lactam-lactim tautomerism can affect nucleotide stability and interactions.
Generating and Modifying Nucleic Acids
- Covalent bonds through phosphodiester linkages form polynucleotide chains, critical for genetic information replication.
- DNA denaturation involves breaking hydrogen bonds, leading to increased UV absorbance, which can be reversible under certain conditions.
Mutagenesis and Genetic Integrity
- Deamination and depurination represent common forms of DNA damage, with significant consequences for genetic stability.
- Chemical alkylation and oxidative damage can modify DNA bases, influencing mutation rates linked to aging and diseases such as cancer.
Applications and Techniques
- Near-complementary hybrids in DNA and RNA are used in detecting specific sequences and amplifying DNA via techniques like PCR.
- Antisense therapy and fluorescent DNA chips utilize hybridization methods for therapeutic and research applications.
Key Terminology
- Nucleoside: Base + Pentose Sugar.
- Nucleotide: Nucleoside + Phosphate.
- TM (Melting Temperature): Higher with more G-C pairs or longer DNA sequences.
- Hydrogen Bonding: Pairs bases in DNA; crucial for duplex stability.
- RNA Hydrolysis: Mostly unstable due to its structure, leading to rapid degradation.
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Description
Test your knowledge on nucleosides and nucleotides with this chapter 8 quiz. Classify the definitions provided and see how well you understand these essential components of nucleic acids. Perfect for students focusing on biochemistry topics.