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Questions and Answers
What are the three parts of a nucleotide?
Who discovered that DNA has a double helix shape?
What did Erwin Chargaff's observations about DNA's nitrogen bases lead to?
What was the significance of Chargaff's rules?
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What did Rosalind Franklin's x-ray of a single DNA molecule reveal?
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What conclusion did Watson & Crick draw from Chargaff's observations?
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Which enzyme is responsible for breaking the bonds between complementary bases in DNA during replication?
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What is the role of DNA polymerase during DNA replication?
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What is the shape of a DNA molecule as described by Watson & Crick?
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What does Chargaff's rule state about the amounts of adenine and thymine in DNA?
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What accounts for the semi-conservative nature of DNA replication?
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What holds together the two polynucleotide chains in a DNA molecule?
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What type of bonding holds adenine to thymine and cytosine to guanine in a DNA molecule?
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What does Chargaff's rule state about the amounts of guanine and cytosine in DNA?
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Study Notes
Nucleotide Structure
- A nucleotide consists of three parts: a sugar molecule, a phosphate group, and a nitrogen base.
Discovery of DNA Structure
- James Watson and Francis Crick discovered that DNA has a double helix shape.
Erwin Chargaff's Observations
- Erwin Chargaff's observations about DNA's nitrogen bases led to the discovery of the base pairing rules.
- Chargaff's rules state that the amount of adenine (A) is equal to the amount of thymine (T), and the amount of guanine (G) is equal to the amount of cytosine (C) in DNA.
- The significance of Chargaff's rules is that they provided a crucial clue for Watson and Crick to determine the double helix structure of DNA.
Rosalind Franklin's Contributions
- Rosalind Franklin's x-ray of a single DNA molecule revealed the helical structure of DNA.
Watson and Crick's Conclusion
- Watson and Crick drew the conclusion that the base pairing of A-T and G-C is responsible for the double helix structure of DNA.
DNA Replication
- The enzyme helicase is responsible for breaking the bonds between complementary bases in DNA during replication.
- DNA polymerase is responsible for adding nucleotides to a template strand during DNA replication.
- The process of DNA replication is semi-conservative, meaning that each new DNA molecule is composed of one old strand and one new strand.
DNA Structure
- The shape of a DNA molecule is a double helix, where two polynucleotide chains are twisted together.
- The two polynucleotide chains are held together by hydrogen bonds between the nitrogen bases.
- Adenine is bonded to thymine and cytosine is bonded to guanine through hydrogen bonds in a DNA molecule.
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Description
Test your knowledge of DNA structure and the scientists behind its discovery with this quiz. Learn about nucleotides, nitrogen bases, and the double helix shape of DNA.
