Protein Synthesis

• Process of Transcription:

  • RNA polymerase binds to DNA
  • The enzyme breaks the hydrogen bonds between the bases
  • The double helix is unwound
  • Antisense strand acts as a template for a mRNA strand
  • Free nucleotides form hydrogen bonds with their complementary bases
  • mRNA strand is the same as the sense strand
  • In RNA, thymine is replaced with uracil
  • RNA polymerase forms phosphodiester bonds between sugar phosphate groups together to form sugar phosphate backbone
  • RNA polymerase reaches stop codon and mRNA detaches from DNA
  • DNA rewinds into double helix
• Process of Translation

  • mRNA leaves nucleus and attaches to ribosome in cytoplasm
  • A tRNA molecule brings an amino acid to the corresponding mRNA codon and attaches
  • Another tRNA molecule brings an amino acid for the next mRNA codon
  • The two amino acids are joined by a peptide bond
  • The first tRNA molecule detaches and is free to collect another amino acid
  • Ribosome moves along mRNA and continues process
  • A polypeptide chain is formed
• What is the amino acid binding site on tRNA called?

  An anticodon
• What is a codon?

  A codon is a triplet of bases that codes for a specific amino acid
• How many tRNA molecules can fit on a ribosome at a time?

  Two
• What are ribosomes made from?

  Ribosomal RNA (rRNA)