PROTEIN SYNTHESIS- transcription + translation

• What is the process that produces proteins from DNA code?

  Protein synthesis
• What are the two stages of protein synthesis?

  Transcription and translation
• Where does transcription take place?

  Nucleus of cells
• Why is transcription necessary?

  DNA cannot pass through nuclear pores
• What is produced during transcription?

  mRNA molecule
• What are the stages of transcription?

  1. DNA unwinds and hydrogen bonds break.
  2. RNA mononucleotides align with DNA template.
  3. RNA nucleotides bond via RNA polymerase.
  4. mRNA molecule is formed and exits nucleus.
• What enzyme catalyzes the bonding of RNA nucleotides?

  RNA polymerase
• What happens to the hydrogen bonds after mRNA is complete?

  They break, reforming the DNA double helix
• What is the function of mRNA after transcription?

  It leaves the nucleus
• What are exons and introns?

  Exons code for proteins; introns do not
• What is pre-mRNA?

  It contains both exons and introns
• What happens during mRNA splicing?

  Introns are removed, leaving only exons
• Where does mRNA splicing take place?

  In eukaryotes only
• Why does pre-mRNA need to be spliced?

  To remove non-coding introns
• What happens to miRNA after splicing?

  It is processed for function
• What is the role of tRNA in translation?

  It brings amino acids to the ribosome
• What shape does tRNA have?

  "Clover leaf" shape
• What is the start codon for translation?

  AUG
• What is the process of translation?

  1. mRNA attaches to ribosome.
  2. tRNA binds to start codon.
  3. Second tRNA binds to next codon.
  4. Peptide bond forms between amino acids.
  5. Ribosome moves along mRNA, releasing tRNA.
  6. Translation continues until stop codon is reached.
• What is a codon?

  A triplet of bases on mRNA
• Where does tRNA bind at the ribosome?

  At the codon on mRNA
• What does tRNA carry to the ribosome?

  Amino acids
• What determines the order of amino acids during translation?

  The sequence of codons on mRNA
• What is the role of mRNA in translation?

  It provides the template for amino acids
• How do the anticodon and codon bind together?

  Through complementary base pairing
• Describe the role of start and stop codons.

  Start codon initiates translation; stop codon terminates it
• How do amino acids join together during translation?

  By forming peptide bonds
• What happens to tRNA after it releases its amino acid?

  It is released from the ribosome
• Compare the structure of mRNA and tRNA.

  • mRNA: single-stranded, long, carries genetic code
  • tRNA: single-stranded, clover leaf shape, carries amino acids
• What is the role of the ribosome in translation?

  It facilitates the binding of tRNA and mRNA