(Unit 1.6) Mutations

• How is a mutation defined in the context of biology?

  A mutation is a change in an organism's DNA.
• What are the two main outcomes of mutations in terms of protein synthesis?

  Mutations can result in a new protein being synthesized or an altered protein being synthesized.
• What is a key characteristic of mutations mentioned in the study material?

  Mutations are spontaneous and random.
• What are mutagenic agents and give two examples?

  Mutagenic agents increase the rate of mutation; examples include UV light and smoking mustard gas.
• What is the general effect of mutations on individuals?

  Mutations normally have a negative or adverse effect on an individual.
• How can advantageous mutations affect variation and evolution?

  Advantageous mutations can increase variation and act as a driving factor of evolution.
• What are the two forms of mutations discussed in the study material?

  • Single gene mutations
  • Chromosomal mutations
• What are the three types of single gene mutations?

  1. Substitution
  2. Insertion
  3. Deletion
• What happens during a substitution mutation?


  A single nucleotide is replaced with a different nucleotide.
• What occurs during an insertion mutation?

  A single nucleotide is added into a DNA sequence.
• What is a deletion mutation?

  A single nucleotide is removed from a DNA sequence.
• What is the impact of a substitution mutation on the DNA nucleotide sequence?

  It may result in a different amino acid being produced during protein synthesis.
• What is a missense mutation?

  A missense mutation is when a single nucleotide substitution results in a different amino acid.
• What is a nonsense mutation?

  A nonsense mutation occurs when a substitution results in an early stop codon, leading to a shorter protein.
• What is a frameshift mutation?

  A frameshift mutation occurs when insertion or deletion of nucleotides shifts the reading frame of the DNA sequence.
• What are the four types of effects of mutations discussed?

  1. Missense mutation
  2. Nonsense mutation
  3. Frameshift mutation
  4. Splice site mutation
• What is a splice site mutation?

  A splice site mutation occurs at a splice site and can affect the retention of exons or the removal of introns.
• What are the four types of chromosomal mutations?

  1. Duplication
  2. Deletion
  3. Inversion
  4. Translocation
• What happens during a duplication mutation?

  Genes from one chromosome become attached to its homologous partner, leading to repeated genes.
• What occurs during a deletion mutation in chromosomes?

  A chromosome breaks in two places, and the middle segment is detached and lost.
• What is an inversion mutation?

  An inversion mutation occurs when a segment of a chromosome breaks, turns around, and reattaches in reverse order.
• What is a translocation mutation?

  A translocation mutation occurs when a section of a chromosome breaks off and attaches to a non-homologous chromosome.
• How do mutations contribute to evolution?

  Mutations, particularly gene duplication, are essential for evolution as they create genetic variation.
• What is the significance of duplicated genes in evolution?

  Duplication allows genes to undergo mutations without affecting the original gene, potentially leading to new advantageous traits.
• What is the relationship between mutations and selective advantage?

  • Mutations can lead to new alleles.
  • New alleles can provide a selective advantage.
  • This advantage can enhance survival and reproduction.
• What is the role of mutations in the process of speciation?

  Mutations contribute to genetic diversity, which is crucial for speciation and the evolution of new species.