Transcription and Translation

• What is produced during transcription?

  mRNA copy of a gene
• Where does transcription occur in eukaryotic cells?

  In the nucleus
• Where does transcription occur in prokaryotic cells?

  In the cytoplasm
• What are the steps of transcription?

  1. RNA polymerase attaches to DNA
  2. DNA strands are separated by helicase
  3. RNA polymerase assembles mRNA strand
  4. RNA polymerase reaches stop signal
• What enzyme initiates transcription?

  RNA polymerase
• What happens to the DNA strands during transcription?

  They are separated by DNA helicase
• What is the role of RNA polymerase during transcription?

  It assembles the mRNA strand
• What replaces thymine in RNA?

  Uracil
• What happens when RNA polymerase reaches a stop signal?

  It stops making mRNA and detaches
• What is pre-mRNA?

  mRNA containing introns and exons
• What is the process of splicing in eukaryotes?

  • Introns are removed
  • Exons are joined together
  • Forms mature mRNA
• What is the difference in mRNA production between eukaryotes and prokaryotes?

  Prokaryotes produce mRNA directly
• Where does translation occur in both eukaryotes and prokaryotes?

  At the ribosomes in the cytoplasm
• What is the role of tRNA during translation?

  It carries amino acids to the ribosome
• What provides energy for the bond formation between tRNA and amino acids?

  ATP
• How does a tRNA molecule attach to mRNA?

  By complementary base pairing
• What happens during the formation of a polypeptide chain?

  • tRNA molecules bring amino acids
  • Amino acids are joined by peptide bonds
  • Process continues until a stop signal is reached
• What happens to the first tRNA molecule after its amino acid is added?

  It moves away from the ribosome
• What indicates the end of translation?

  A stop signal on the mRNA
• What is produced at the end of translation?

  A polypeptide chain
• What is the overall process of protein synthesis?

  1. Transcription: DNA to mRNA
  2. Splicing: Pre-mRNA to mRNA (in eukaryotes)
  3. Translation: mRNA to polypeptide chain