lecture 15 - mutations

• What is the direction of RNA synthesis during transcription?

  5’→3’ direction
• What does RNA Polymerase do?

  It synthesizes a new mRNA strand from the template strand of DNA.

  
• How is the coding strand related to the mRNA strand?

  The coding strand is identical to the mRNA strand.
• What is a point mutation?

  A change in the DNA sequence that affects a single base.
• What is a silent mutation?

  A silent mutation occurs when there is no change in the amino acid sequence.
• What is a missense mutation?

  A missense mutation occurs when a sequence change results in a different amino acid.

  
• What is a nonsense mutation?

  A nonsense mutation occurs when a sequence change results in a stop codon.

  
• What is a frameshift mutation?

  A frameshift mutation is an insertion or deletion of a base that changes all the following codons.
• What is the effect of a Gain-of-Function (GOF) mutation?

  It results in a more active protein.
• What is the effect of a Loss-of-Function (LOF) mutation?

  It results in an inactive or less active protein.
• What are the symptoms of Cystic Fibrosis?

  • Wheezing
  • Chronic lung infections
  • Recurrent sinusitis
  • Pulmonary hypertension
  • Foul-smelling, greasy stools
  • Intestinal blockages
  • Chronic or severe constipation
• What are the symptoms of Sickle Cell Anemia?

  • Anemia (fatigue, shortness of breath, dizziness, or irregular heartbeat)
  • Fever
  • Acute Chest Syndrome: Chest pain, coughing, fever
  • Painful swelling of the hands and feet
• What does Ube3A encode for?

  Ube3A encodes for an enzyme, ubiquitin ligase.
• What is the function of Ube3A?

  Ube3A targets proteins for degradation by tagging proteins with ubiquitin.

  
• What types of disorders are associated with mutations in Ube3A?

  Mutations in Ube3A have been associated with various neurodevelopmental disorders.
• How can you determine whether a mutation in Ube3A is Loss of Function, Gain of Function, or normal?

  By measuring the mean ligase activity.

  
• What conclusions can be drawn from the Ube3A ligase activity data?

  • Q588E shows Gain-of-Function with 389% activity.
  • Q588P shows Loss-of-Function with 2% activity.
  • Q588S, Q588T show normal activity.
• What are the different types of mutations that can occur in genes?

  • Point mutations: silent, missense, nonsense
  • Frameshift mutations: insertions or deletions
  • Gain-of-Function (GOF) mutations
  • Loss-of-Function (LOF) mutations

  
• How can mutations in genes change proteins and traits?

  • Alter amino acid sequences
  • Change protein function (active/inactive)
  • Result in various phenotypic traits