Mutations

• What is a gene mutation?

  A change in DNA base pair sequence
• How can a gene mutation affect a polypeptide?

  It can result in an altered polypeptide
• When do mutations occur?

  Continuously and randomly during DNA replication
• Why do most mutations not alter the polypeptide significantly?

  Because the genetic code is degenerate
• What are the potential effects of mutations?

  They can be advantageous or disadvantageous
• How do mutations affect the triplet code?

  They can change the sequence of amino acids
• What is the impact of altered amino acid sequences on proteins?

  It affects the final 3D shape of the protein
• What is substitution in the context of mutations?

  Swapping one base for another in DNA
• Does substitution cause a frameshift mutation?

  No, it does not cause a frameshift
• What is a potential effect of substitution on amino acids?

  It can alter a single amino acid
• What condition can result from a substitution mutation?

  Sickle cell anaemia
• What is an insertion mutation?

  A base is randomly inserted into DNA
• What type of mutation does insertion cause?

  It causes a frameshift mutation
• How does an insertion mutation affect downstream triplets?

  It changes every downstream triplet
• What is a deletion mutation?

  A base is randomly deleted from DNA
• How do deletion mutations compare to insertion mutations?

  They have similar effects on triplets
• What are the types of mutations discussed?

  • Substitution
  • Insertion
  • Deletion
• What are the consequences of mutations on proteins?

  • Can lead to altered polypeptides
  • May cause advantageous variations
  • Can result in diseases
• What is cystic fibrosis?

  A genetic disease of cell membranes
• What causes cystic fibrosis?

  A recessive allele of the CFTR gene
• Where is the CFTR gene located?

  On chromosome 7
• What does the CFTR gene code for?

  Chloride ion channels
• What is the function of chloride ion channels?

  Required for secretion of sweat, mucus, and digestive juices
• What happens when there is a mutation in the CFTR gene?

  Production of non-functional chloride channels
• How many mutations in the CFTR gene can lead to cystic fibrosis?

  Many mutations
• Why do chloride ions need a channel for transport?

  They are charged and cannot pass through the membrane
• What is the role of mucus in the lungs?

  Traps dust and pathogens
• How are the lungs adapted for rapid gas exchange?

  They have a large surface area and thin walls
• What are the key features of cystic fibrosis and its genetic basis?

  • Genetic disorder caused by CFTR gene mutation
  • Located on chromosome 7
  • Recessive allele leads to non-functional chloride channels
  • Affects secretion of sweat, mucus, and digestive juices