Lecture Notes: DNA vs RNA
Introduction
- DNA often gets credit for its role in genetics due to its iconic double helix structure.
- RNA is equally important for translating genetic information into proteins.
- The RNA World Hypothesis suggests RNA might have predated DNA.
Presence in Organisms
- DNA and RNA are found in all living organisms.
- Eukaryotic cells: DNA in nucleus; RNA in and out of nucleus.
- Prokaryotic cells: No nucleus.
Nucleic Acids
- Both DNA and RNA are nucleic acids, a type of biomolecule.
- Monomer: Nucleotide, consisting of phosphate, sugar, and a base.
Structural Differences
- DNA
- Generally double-stranded with antiparallel strands.
- Sugar: Deoxyribose.
- Bases: Adenine (A), Thymine (T), Guanine (G), Cytosine (C).
- Mnemonics: A-T ("apples in the tree"), C-G ("car in the garage").
- RNA
- Generally single-stranded.
- Sugar: Ribose.
- Bases: Adenine (A), Uracil (U), Guanine (G), Cytosine (C).
- Mnemonics: A-U ("apples under"), C-G ("car in the garage").
Role in Protein Synthesis
- RNA aids in protein synthesis, working with DNA.
- Types of RNA:
- mRNA (Messenger RNA): Carries DNA message to ribosome.
- rRNA (Ribosomal RNA): Major component of ribosomes.
- tRNA (Transfer RNA): Transfers amino acids to match mRNA codons.
- Codons in mRNA determine which amino acids are transferred to form polypeptide chains, leading to protein formation.
Quiz Questions
- Question: If I have 8 DNA nucleotides, how many DNA bases do I have? How many base pairs?
- Answer: 8 bases, 4 base pairs.
- Question: What are the complementary DNA bases for A, T, T, G, A, C?
- Answer: T, A, A, C, T, G.
- Question: What are the complementary RNA bases for the DNA strand A, T, T, G, A, C?
- Answer: U, A, A, C, U, G (using uracil instead of thymine).
Final Notes
- Models of DNA/RNA can’t capture 3D shape, bases per turn, chirality.
- Further exploration and reading recommended to understand these complexities.
Conclusion: Stay curious and explore more about DNA and RNA beyond introductory material.