L10. Protein synthesis

• What are the two types of sugars found in DNA and RNA?

  DNA contains deoxyribose, RNA contains ribose
• Which base does DNA use that mRNA does not?

  DNA uses thymine, mRNA uses uracil
• How do the structures of DNA and mRNA differ?

  DNA has a double helix, mRNA is single stranded
• Where do DNA and mRNA reside in cells?

  DNA and mRNA always reside in the nucleus
• What is the purpose of mRNA processing?

  To protect it from degradation
• What does mRNA processing help with besides protection?

  It helps mRNA exit the nucleus
• What role do snRNPs play in mRNA processing?

  They help attract mRNA for splicing
• What is the site of translation in cells?

  Ribosomes
• What are the learning objectives of Lecture 14 on proteins?

  • Explain need for defined polypeptides
  • Importance of base-pairing in protein synthesis
  • Discuss machinery and materials for translation
  • Characteristics of the genetic code
  • Processing and targeting proteins correctly
• What is the basic concept of translation?

  The cell builds a polypeptide from a genetic message
• How does mRNA interact with ribosomes during translation?

  mRNA is moved through a ribosome
• What does tRNA do during translation?

  It adds amino acids to the growing polypeptide chain
• What is the start codon in mRNA?

  AUG
• What is the role of the 30 S subunit in translation initiation?

  It binds to the start codon on mRNA
• What amino acid does the initiator tRNA carry?

  Methionine (Met)
• What is required for the initiation complex to form?

  Protein initiation factors and energy (GTP)
• What are the three steps involved in elongation during translation?

  1. Codon recognition (requires energy)
  2. Peptide bond formation (catalyzed by rRNA)
  3. Translocation (requires energy)
• What happens when a STOP codon appears in the A site of the ribosome?

  A release factor protein binds and frees the peptide chain
• How long does it take for a ribosome to make an average-sized polypeptide?

  About one minute
• What is the significance of the genetic code?

  It defines the association of codons with anti-codons
• What is the composition of ribosomes?

  Ribosomes are made from rRNA and protein
• What is the role of signal sequences in proteins?

  They target proteins for export from the cell
• What happens during post-translational modification?

  Proteins are processed and targeted to their locations
• How many novel mutations does each new human have?

  Approximately 64 novel mutations
• What is the general nature of mutations according to H.J. Muller?

  The majority are detrimental to survival
• What is the triplet code's role in translation?

  It is translated to amino acids on ribosomes
• What are the phases of translation?

  1. Initiation
  2. Elongation
  3. Termination
• What is the significance of codon redundancy?

  Most codons are encoded by more than one codon
• How many possible codons exist?

  64 possible codons
• What are the two types of sugars found in DNA and RNA?

  DNA contains deoxyribose, RNA contains ribose
• Which base does DNA use that RNA does not?

  DNA uses thymine, RNA uses uracil
• What is the role of polyribosomes in protein synthesis?

  They allow multiple copies of polypeptides to be made
• What are the characteristics of the genetic code?

  • Defines association of codons with anti-codons
  • Codons show redundancy
  • 64 codons for 20 amino acids
• How do the structures of DNA and RNA differ?

  DNA has a double helix, RNA is single stranded
• Where do DNA and mRNA reside in cells?

  DNA resides in the nucleus, mRNA exits
• What is the role of mRNA processing?

  It protects mRNA from degradation
• What does mRNA processing help with besides protection?

  It helps mRNA exit the nucleus
• What is the site of translation in cells?

  Ribosomes are the site of translation
• What are the learning objectives for Lecture 14 on proteins?

  • Explain need for defined polypeptides
  • Importance of base-pairing in protein synthesis
  • Discuss machinery and materials for translation
  • Explain characteristics of the genetic code
  • Importance of protein processing and targeting
• What is the basic concept of translation?

  The cell builds a polypeptide from mRNA