A gene variant is a permanent change in the DNA sequence that makes up a gene. This type of genetic change used to be known as a gene mutation, but because changes in DNA do not always cause disease, it is thought that gene variant is a more accurate term.
2. How does it affect a human being?
When a variant alters a protein that plays a critical role in the body, it can disrupt normal development or cause a health condition. A condition caused by variants in one or more genes is called a genetic disorder. In some cases, gene variants are so severe that they prevent an embryo from surviving until birth.
3. Which type of gene mutation has the least effect in an organism?Why?
A point mutation
The change of a single nitrogen base in a DNA sequence—is usually the least harmful type of DNA mutation. Codons are a sequence of three nitrogen bases in a row that are "read" by messenger RNA during transcription.
5. What might be the causes of gene mutation?
Mutations arise spontaneously at low frequency owing to the chemical instability of purine and pyrimidine bases and to errors during DNA replication. Natural exposure of an organism to certain environmental factors, such as ultraviolet light and chemical carcinogens (e.g., aflatoxin B1), also can cause mutations
