Mutations

Types of Mutations

  • Mutations refer to changes that occur in our DNA sequence.
  • There are two main types of mutations, germline mutations and somatic mutations. Germline mutations occur in germ cells, which are the reproductive cells that give rise to sperm or eggs, while somatic mutations occur in the body cells and are not passed onto the offspring.
  • They can also be categorized as single gene mutations or chromosome mutations. Single gene mutations involve changes in a small segment of DNA, affecting a single gene. Chromosome mutations involve changes in a large segment of DNA and can affect many genes.

Cause of Mutations & Effects

  • Mutations can be spontaneous, appearing without any specific cause, or they can be induced by various factors including radiation and certain chemicals.
  • Mutations can have a range of effects on the organism, depending on where they occur and how they alter gene activity. Some mutations can be harmful, some can be beneficial, while many are neutral having little to no effect on the organism.
  • Mutations in protein coding genes can change the function of the protein leading to abnormal traits or diseases.
  • Beneficial mutations could lead to adaptation, survival, and evolution over time, as they may offer an advantage to organisms in certain environments.

DNA Repair and Mutation Prevention

  • Cells have numerous mechanisms for DNA repair to prevent or correct mutations. DNA polymerase, for example, has proofreading capabilities that can identify and correct mistakes during DNA replication.
  • Other repair systems, like DNA mismatch repair, are more general and can correct different types of errors in the DNA sequence.
  • However, if the mistakes are not repaired or are repaired incorrectly, they can become permanent mutations.

Role of Mutations in Evolution

  • Despite potential negatives, mutations play a crucial role in evolution as they provide the genetic variation necessary for natural selection to occur.
  • Natural selection favors organisms with beneficial mutations that provide survival or reproductive advantages, allowing them to pass these beneficial traits to their offspring.
  • Over time, those beneficial mutations become a standard part of the population’s gene pool, leading to evolution of the species.

Genetic Disorders

  • Genetic disorders can result from mutations that disturb an organism’s genome in a way that causes physical or mental abnormalities.
  • Some genetic disorders are inherited, such as cystic fibrosis which is due to a mutation in the CFTR gene, or Huntington’s disease caused by a mutation in the HTT gene.
  • However, many genetic disorders, such as certain forms of cancer, are the result of mutations that occur during an organism’s lifetime.