1.2 Proteins Synthesis

• Gene


  A segment of DNA that codes for a single protein
• Unique sequence of nucleotides


  To code for each specific protein
• Proteins


  They are made of amino acids
• Structure and function of a protein

  Depends on the order of amino acids
• Protein Synthesis - Transcription

  1. Genetic information in a gene is copied to messenger RNA (mRNA)

  2. DNA unwinds and separates, RNA nucleotides attracted to complementary pairs, RNA polymerase creates mRNA strand, mRNA detaches for processing, original DNA strand comes back together
• Splicing


  Introns are removed, exons are rejoined in the final mRNA molecule
• Protein Synthesis

  DNA - transcription - RNA - translation - Protein
• Genes are made up of

  • Introns (non-coding regions of DNA)
  • Exons (coding regions)
• Protein synthesis

  Involves rewriting DNA as RNA (transcription) and then translating the RNA into a protein
• Translation (mRNA-protein)

  mRNA attaches to ribosome, tRNA matches anticodon to codon, amino acids joined together until stop codon, amino acid chain moves to rough ER
• Types of RNA

  Messenger RNA (mRNA), Transfer RNA (tRNA), Ribosomal RNA (rRNA)
• Protein Structure

  Amino acids join to form a polypeptide chain during translation, chain folds to form a protein, final 3D structure determines function
• Levels of protein structure

  • Primary Structure
  • Secondary Structure
  • Tertiary Structure
  • Quaternary Structure
• Primary Structure

  Sequence of amino acids joined together in a chain
• Secondary Structure


  Peptide chain folds into shapes held together by hydrogen bonds
• Tertiary Structure


  Proteins fold further into complex 3D shapes held by interactions between amino acids
• Quaternary Structure

  Joining of 2 or more folded peptide chains to form a complete protein