Lecture Notes: From DNA to Protein Synthesis

Introduction to DNA and Traits

• DNA contains genetic information that determines traits, such as eye color.
• Eye color is determined by pigments, which are made via proteins coded by genes (segments of DNA).

Importance of Proteins

• Proteins are crucial for various functions:
  • Transport
  • Structural support
  • Enzymatic activities
  • Protection of the body
• Protein synthesis is essential for life.

Overview of DNA in Cells

• DNA is located in the nucleus of cells.
• Some DNA is non-coding or makes genes not currently activated.
• Active protein-coding genes are the focus for protein synthesis.

Role of RNA

• RNA is a nucleic acid similar to DNA with a key role in protein synthesis.
• RNA vs. DNA: RNA differs slightly in structure and function.

Steps in Protein Synthesis

1. Transcription

• Occurs in the nucleus.
• RNA polymerase helps transcribe DNA to form mRNA (messenger RNA).
• mRNA is a single-stranded RNA that carries the genetic message from DNA.
• mRNA undergoes significant editing before it is functional.
• In eukaryotes, mRNA exits the nucleus and attaches to a ribosome in the cytoplasm.

2. Translation

• Occurs in the cytoplasm.
• Involves ribosomes (made of rRNA - ribosomal RNA) which build proteins.
• tRNA (transfer RNA):
  • Carries amino acids, the building blocks of proteins.
  • Matches with mRNA codons through complementary anticodons.
  • Transfers amino acids to the growing protein chain.
• Codons:
  • Read as triplets (e.g., AUG) on mRNA.
  • Each codon corresponds to a specific amino acid.
  • AUG is a start codon coding for methionine.
  • Codon chart helps determine amino acid coding.

Process Details

• tRNA with anticodon UAC pairs with mRNA codon AUG, transferring methionine.
• Amino acids link via peptide bonds to form a protein chain.
• Process continues until a stop codon is reached, signaling the end of protein synthesis.

Conclusion

• mRNA, rRNA, and tRNA work together to translate DNA’s instructions into proteins.
• Post-translation modifications and transport of proteins occur depending on function.
• Protein synthesis is a complex process, with numerous layers of regulation and modification.

Final Note

• Stay curious and explore further the intricate processes involving DNA and protein synthesis.