Protein synthesis

• What is the first stage of protein synthesis?

  Transcription
• Where does transcription occur?

  In the nucleus
• What role does DNA helicase play in transcription?

  It breaks hydrogen bonds in DNA
• What is the template strand in transcription?

  The non-coding strand guiding mRNA synthesis
• How does RNA polymerase synthesize mRNA?

  It moves from 3' to 5' direction
• What is the direction of mRNA synthesis?

  5' to 3'
• Which base pairs with Adenine in RNA?

  Uracil (U)
• Which base pairs with Cytosine?

  Guanine (G)
• What happens when RNA polymerase reaches a terminator sequence?

  It detaches from the mRNA strand
• How does the newly synthesized mRNA exit the nucleus?

  Through nuclear pores
• What is the second stage of protein synthesis?

  Translation
• Where does translation occur?

  In the cytoplasm on ribosomes
• What does the mRNA strand bind to during translation?

  A ribosome
• What are codons?

  Sets of three nucleotides in mRNA
• What is the role of tRNA in translation?

  To bring specific amino acids to the ribosome
• How does tRNA ensure accurate base pairing?

  It has an anticodon complementary to mRNA codon
• What does the ribosome do as tRNA delivers amino acids?

  Catalyzes the formation of peptide bonds
• What signals the end of translation?

  Encountering a stop codon
• What are the stop codons in translation?

  UAA, UAG, or UGA
• What happens when a release factor binds to the ribosome?

  The completed polypeptide chain is released
• Structure of tRNA?


  Single helix with a clover leaf shape, anticodon at one end which binds with the codon of mRNA
• DNA polymerase function?


  Catalyses condensation reactions to form phosphodister bonds between nucleotides during the synthesis of a new DNA strand