Podcast
Questions and Answers
What is the primary structure of DNA?
What is the primary structure of DNA?
- The higher-order folding
- The double-stranded helix
- The phosphate backbone
- The nucleotide sequence (correct)
Which of the following components is NOT part of a DNA nucleotide?
Which of the following components is NOT part of a DNA nucleotide?
- Nitrogenous base
- Deoxyribose sugar
- Phosphate group
- Amino acid (correct)
What does the secondary structure of DNA refer to?
What does the secondary structure of DNA refer to?
- The formation of the double-stranded helix (correct)
- The packing of DNA into chromosomes
- The linear arrangement of nucleotides
- The single-stranded form of DNA
Which statement correctly describes the tertiary structure of DNA?
Which statement correctly describes the tertiary structure of DNA?
How are the carbons in the sugar component of DNA numbered?
How are the carbons in the sugar component of DNA numbered?
What are the names of the two purine bases found in nucleic acids?
What are the names of the two purine bases found in nucleic acids?
Which of the following is NOT a pyrimidine base?
Which of the following is NOT a pyrimidine base?
What type of bond links the sugar and phosphate groups in a nucleotide?
What type of bond links the sugar and phosphate groups in a nucleotide?
How are the two strands of DNA structured with respect to their direction?
How are the two strands of DNA structured with respect to their direction?
Which component is found in RNA but not DNA?
Which component is found in RNA but not DNA?
What stabilizes the double helix structure of DNA?
What stabilizes the double helix structure of DNA?
In the notation 5’ C-A-G 3’, what does the 5’ signify?
In the notation 5’ C-A-G 3’, what does the 5’ signify?
What is the 'legs of the ladder' in the DNA double helix structure made of?
What is the 'legs of the ladder' in the DNA double helix structure made of?
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Study Notes
Central Dogma of Molecular Biology
- Information flows in the order: DNA → RNA → Protein.
What is DNA?
- Deoxyribonucleic acid (DNA) contains essential information for building and maintaining organisms.
- Functions as the primary unit of heredity across all forms of life.
Structure of DNA
- Primary Structure: Defined by the nucleotide sequence.
- Secondary Structure: Formed as a double-stranded helix.
- Tertiary Structure: Represents higher-order folding necessary for DNA packaging.
Nucleotide Composition
- Composed of three parts: Phosphate group, deoxyribose sugar, and nitrogenous base.
- Carbons in the sugar are numbered from 1’ to 5’.
Nitrogenous Bases
- Purines: Adenine (A) and Guanine (G).
- Pyrimidines (in DNA): Cytosine (C) and Thymine (T).
- Pyrimidines (in RNA): Uracil (U) replaces Thymine.
Double Helix Structure
- Formed by two strands twisted together, known as a double helix.
- Backbone: Made of deoxyribose sugar and phosphate groups linked by phosphodiester bonds.
- Nitrogen bases pair in the center held together by hydrogen bonds.
Phosphodiester Bonds
- Link nucleotides through the bond between the 5’ phosphate group of one nucleotide and the 3’ hydroxyl group of another.
Antiparallel Orientation
- DNA strands are complementary and run in opposite directions (5’ to 3’).
Stability of DNA
- Stability is contributed by:
- Hydrogen bonding between base pairs (A pairs with T, G pairs with C).
- Hydrophobic interactions among stacked bases in the helix.
DNA Structure Analogy
- Double helix resembles a ladder:
- "Ladder rungs": Comprised of nitrogenous bases (A, T, G, C).
- "Ladder legs": Formed by the sugar-phosphate backbone.
Discovery
- James Watson and Francis Crick developed the three-dimensional model of DNA structure.
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