Overview
This lecture introduces the similarities and differences between DNA and RNA, focusing on their structures, functions, and roles in protein synthesis.
DNA vs. RNA Structure
- DNA has a double helix structure, is generally double-stranded, and runs antiparallel.
- RNA is generally single-stranded and can be found both inside and outside the nucleus.
- DNA’s sugar is deoxyribose; RNA’s sugar is ribose.
- DNA bases: adenine (A), thymine (T), guanine (G), cytosine (C).
- RNA bases: adenine (A), uracil (U), guanine (G), cytosine (C).
Location and Function
- DNA is found in the nucleus of eukaryotic cells, while RNA is present both inside and outside the nucleus.
- Prokaryotic cells lack a nucleus, so DNA and RNA are found in the cytoplasm.
- DNA stores genetic information and codes for traits.
- RNA helps express genetic information and is essential for protein synthesis.
Types of RNA and Their Roles
- mRNA (messenger RNA) carries genetic messages from DNA to ribosomes.
- rRNA (ribosomal RNA) forms a major part of ribosome structure, where proteins are synthesized.
- tRNA (transfer RNA) brings amino acids to the ribosome to match mRNA codons during translation.
Nucleotide Structure
- Both DNA and RNA are nucleic acids made up of nucleotides.
- Each nucleotide consists of a phosphate, a sugar, and a base.
Base Pairing Rules
- DNA base pairs: A pairs with T (Apples in the tree), C pairs with G (Car in the garage).
- RNA base pairs: A pairs with U (Apples under), C pairs with G (Car in the garage).
- In DNA, each base pair involves one base from each strand.
Practice Questions Review
- 8 DNA nucleotides have 8 bases and form 4 base pairs.
- Given DNA strand A, T, T, G, A, C, the complementary DNA strand is T, A, A, C, T, G.
- For RNA complementary to DNA A, T, T, G, A, C, the sequence is U, A, A, C, U, G.
Key Terms & Definitions
- Nucleotide — The building block of nucleic acids; consists of a phosphate, sugar, and base.
- Double helix — The twisted ladder shape of DNA.
- mRNA (messenger RNA) — RNA that carries genetic messages from DNA to ribosomes.
- rRNA (ribosomal RNA) — RNA that makes up part of the ribosome.
- tRNA (transfer RNA) — RNA that brings amino acids to the ribosome matching mRNA codons.
- Base pairing — The specific hydrogen bonding between bases: A-T/U and C-G.
Action Items / Next Steps
- Watch the protein synthesis video for more details on RNA types and roles.
- Review links and further reading suggested in the description for deeper understanding.