bio topic 4: protein synthesis

• What are the two stages of protein synthesis?

  Transcription and translation
• What is transcription?

  Copying a gene into mRNA
• Where does transcription occur?

  Inside the nucleus
• What is the role of mRNA in transcription?

  It is a copy of the gene
• Why can't DNA leave the nucleus?

  It is too big to leave
• What enzyme is used to unwind the DNA during transcription?

  DNA helicase
• What is the result of transcription?

  A copy of mRNA is created
• What is pre-mRNA?

  It is the initial mRNA before modification
• What is splicing in mRNA processing?

  Removing introns from pre-mRNA
• What are introns?

  Sequences that do not code for amino acids
• What is the role of a spliceosome?

  To remove introns from pre-mRNA
• What is the final step of protein synthesis?

  Translation
• Where does translation occur?

  In the cytoplasm
• What is the role of tRNA in translation?

  Brings specific amino acids to ribosome
• What does the ribosome do during translation?

  Holds mRNA and tRNA in place
• What is required to create a peptide bond?

  An enzyme and ATP
• What happens when the ribosome reaches a stop codon?

  Translation ends and ribosome detaches
• Where does the polypeptide chain go after translation?

  To the Golgi body for modifications
• What are the key steps in transcription?

  1. DNA unwinds to expose strands
  2. RNA nucleotides align with complementary bases
  3. RNA polymerase joins nucleotides to form mRNA
  4. Pre-mRNA undergoes splicing to remove introns
  5. Finished mRNA consists only of exons
• What are the key steps in translation?

  1. mRNA attaches to ribosome at start codon
  2. tRNA brings specific amino acids
  3. Ribosome holds mRNA and tRNA in place
  4. Peptide bonds form between amino acids
  5. Process continues until stop codon is reached