Understanding DNA to Protein Translation

Oct 11, 2024

Lecture Notes: From DNA to Protein Translation

Introduction

  • Understanding how DNA information is converted into proteins.
  • Key focus on components and process of translation.

Components of Translation

Types of RNA

  • Messenger RNA (mRNA):
    • Synthesized from DNA by RNA polymerase.
    • Carries genetic code from DNA to ribosome.
  • Ribosomal RNA (rRNA):
    • Structural and functional component of ribosomes.
  • Transfer RNA (tRNA):
    • Brings amino acids to the ribosome.

Structure of mRNA

  • Broken into codons, groups of three nucleotide bases.
  • Each codon specifies a specific amino acid.
    • Example: AUG starts the protein synthesis with methionine.

Genetic Code and Codons

  • Codons are sequences of three mRNA bases.
    • AUG: Start codon, encodes methionine.
    • UUU & UUC: Encode phenylalanine.
    • AAA: Binds to anticodon UUU on tRNA, brings lysine.
  • Anticodons:
    • Complementary sequences on tRNA.
    • Bind to mRNA codons, ensuring correct amino acid addition.

Historical Context

  • Decoding the genetic code was pivotal in biology.
  • Initial theories and experiments:
    • One base for each amino acid was insufficient (only 4 combinations).
    • Two bases per amino acid allowed 16 combinations (still insufficient).
    • Three bases led to 64 combinations, explaining encoding for 20 amino acids.

Reading the Genetic Code

  • Codon table allows identification of amino acids from mRNA sequences.
  • Example: CAC codes for Histidine.
  • Start Codon: AUG.
  • Stop Codons: UAA, UAG, UGA (do not encode amino acids).

tRNA Structure

  • tRNA can base pair with itself, forming a cloverleaf shape.
  • Anticodon: Base pairs with mRNA codon.
  • Amino Acid Attachment Site: Opposite the anticodon.
  • Aminoacyl tRNA Synthetase:
    • Enzyme that charges tRNA by adding amino acids.
    • Requires energy (ATP) for each amino acid attachment.

Energy in Translation

  • Charging tRNA with amino acids consumes ATP.
  • Illustration of cellular energy usage in protein synthesis.

Upcoming

  • Animated overview of translation process.
  • Detailed explanation of translation steps.