Questions and Answers
Nucleic acids are polymers made up of which of the following monomers? (Select all that apply)
What is the difference between a ribonucleotide and a deoxyribonucleotide?
Ribonucleotides have a hydroxyl group on the 2 carbon of their sugar subunit.
What is/are the variable structure(s) of a nucleotide?
Which of the following includes all of the pyrimidines found in RNA and DNA?
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When nucleotides polymerize to form a nucleic acid, what occurs?
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If you wanted to radioactively label the nucleic acids separately from the protein, you would use radioactive?
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What feature of single nucleotides provides the energy needed for polymerization when nucleic acids are formed?
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Which of the following descriptions best fits the class of molecules known as nucleotides?
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Which of the following are pyrimidine nitrogenous bases?
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Which of the following are purine nitrogenous bases?
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The difference between the sugar in DNA and the sugar in RNA is that the sugar in DNA?
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If cells are grown in a medium containing radioactive 32P-labeled phosphate, which of these molecules will be labeled?
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What is the difference (if any) between the structure of ATP and the structure of the precursor of the A nucleotide in RNA?
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Nucleic acids have a definite polarity, or directionality. How are these ends described?
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If a double-stranded DNA sample were composed of 10 percent thymine, what would be the percentage of guanine?
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DNA double helices are soluble in water but insoluble in alcohol. How do these physical properties reflect the chemical structure of the DNA molecule?
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You have a polymer of DNA with 10 adenine bases followed by 10 cytosine bases. If that strand bonded to a strand of 20 thymine bases, how would the double helix shape vary from a typical DNA double helix?
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Which of the following best describes DNA's secondary structure?
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Which of the following did Watson and Crick already know when they were trying to determine the structure of DNA? The number of?
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Franklin and Wilkins analyzed DNA by bombarding DNA crystals with X-rays. Their analysis yielded two numbers that sparked interest, 3.4 nm and 0.34 nm. What is the significance of these numbers?
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A double-stranded DNA molecule contains a total of 120 purines and 120 pyrimidines. This DNA molecule could be composed of?
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What is the structural feature that allows DNA to replicate?
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Enzymes that break down DNA catalyze the hydrolysis of the covalent bonds that join nucleotides together. What would happen to DNA molecules treated with these enzymes?
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Which of the following pairs of base sequences could form a short stretch of a normal double helix of DNA?
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Compare proteins to nucleic acids. Which of the following is TRUE?
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Which of the following statements best summarizes the differences between DNA and RNA?
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Why is it that RNA can catalyze reactions but DNA cannot?
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Both DNA and RNA?
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RNA and proteins combine in cells to form structures called ribosomes. Based on their chemical structures, do you think protein or RNA molecules actually form the active site within the ribosome?
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Which of the following statements about the 5' end of a polynucleotide strand of RNA is correct?
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One of the primary functions of RNA molecules is to?
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If 14C-labeled uracil is added to the growth medium of cells, what macromolecules will be labeled?
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In the context of chemical evolution, DNA's structure is interesting because it suggests a possible copying mechanism. What about DNA's structure facilitates copying?
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DNA is the main hereditary material of all life. However, DNA lacks one important characteristic for the first forms of life. Why have researchers rejected the idea that DNA was found in the first life-form?
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Why do researchers think the first self-replicating molecule was RNA?
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Recall the Bartel lab group experiment to create a ribozyme from scratch. If they had created exact copies of each ribozyme (rather than creating copies with a few differences), the ribozymes would have?
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Bartel's research group showed that an RNA replicase ribozyme could be created by?
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The work of Bartel's group on the ribozyme RNA replicase supports which conclusion?
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Study Notes
Nucleic Acids and Nucleotide Structure
- Nucleic acids are polymers composed of nucleotides, consisting of a nitrogenous base, sugar, and phosphate group.
- Ribonucleotides differ from deoxyribonucleotides by the presence of a hydroxyl group on the 2' carbon of their sugar subunit.
- The variable structures of nucleotides are found in the sugar and base components.
- Pyrimidines in RNA and DNA include cytosine, uracil, and thymine.
- Nucleotides polymerize via covalent bonds between the sugar of one nucleotide and the phosphate of another.
Molecular Labels and Energy Sources
- Radioactive phosphorus is used to label nucleic acids due to the presence of phosphate groups.
- The energy required for nucleotide polymerization comes from phosphate groups.
DNA and RNA Characteristics
- DNA is structured as double antiparallel helical strands with a defined 5' and 3' polarity.
- The sugar in RNA contains one more oxygen atom than the sugar in DNA.
- The complementary pairing of nitrogenous bases enables DNA replication.
- The structural feature that allows DNA to replicate is its complementary base pairing.
Structural Features and Base Pairing
- The nucleotide composition of DNA maintains equal numbers of purines (adenine and guanine) and pyrimidines (cytosine and thymine).
- In DNA, a double-stranded arrangement results in consistent base pairing, leading to a helical structure.
- For a given DNA sample with known thymine content, guanine levels can be deduced based on base pairing rules (A=T and G≡C).
Experimental Findings and Molecular Functions
- Ribosomes, composed of RNA and proteins, serve as sites for protein synthesis, with both molecules potentially facilitating catalytic activity.
- RNA molecules can serve multiple functions, including the synthesis of proteins and self-replication capabilities in the context of early life forms.
Evolutionary Perspectives
- The hypothesis that RNA was the first self-replicating molecule stems from its ability to carry genetic information and catalyze reactions.
- Bartel's experiments suggest an RNA world capable of producing self-replicating molecules through random selection and optimization of ribozymes.
Key Distinctions
- Enzymatic breakdown of DNA involves hydrolysis of phosphodiester linkages, leading to the separation of strands.
- Unlike DNA, which does not catalyze reactions, RNA can function enzymatically due to its more reactive sugar and diverse roles in cellular processes.
Conclusion
- DNA encodes genetic information; however, it lacks the catalytic function seen in RNA, suggesting early life forms may have relied on RNA for self-replication and functioning.
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Description
Test your knowledge on nucleic acids and their building blocks with this quiz. Focus on the differences between ribonucleotides and deoxyribonucleotides, and reinforce your understanding of nucleotides. Ideal for biology students!