Transversion

Diagram showing all possible transitions and transversions in DNA.

A transversion is a type of point mutation in DNA where a purine is substituted for a pyrimidine, or vice versa. This contrasts with a transition, where a purine is replaced with another purine, or a pyrimidine is replaced with another pyrimidine.

Types of Transversions

Transversions can be categorized based on the specific bases involved:

• Purine to Pyrimidine:

 * Adenine (A) to Cytosine (C) or Thymine (T)
 * Guanine (G) to Cytosine (C) or Thymine (T)

• Pyrimidine to Purine:

 * Cytosine (C) to Adenine (A) or Guanine (G)
 * Thymine (T) to Adenine (A) or Guanine (G)

Biological Significance

Transversions are less common than transitions but can have significant effects on the genetic code. Because they involve a change in the chemical structure of the base, transversions can lead to more drastic changes in the amino acid sequence of proteins, potentially altering protein function.

Mutational Effects

Transversions can result in:

• Missense mutations, where the change in base leads to the incorporation of a different amino acid in the protein.
• Nonsense mutations, where the change creates a premature stop codon, leading to truncated proteins.
• Silent mutations, where the change does not affect the amino acid sequence due to the redundancy of the genetic code.

Detection and Analysis

Transversions can be detected through various molecular biology techniques, such as DNA sequencing and polymerase chain reaction (PCR). Understanding the frequency and distribution of transversions in a genome can provide insights into the mechanisms of mutagenesis and the evolutionary pressures acting on an organism.

Related Pages

• Transition (genetics)
• Point mutation
• DNA replication
• Genetic code