Gene Mutations

1. Gene Mutations A change in the DNA of a gene is called a mutation. Mutations in gametes can be passed on to the offspring of the affected individual, but mutations in body cells affect only the individual in which they occur in.

2. Types of Gene Mutations: 1. point/substitution – a single nucleotide changes; or the wrong amino acid is placed during protein synthesis 2. insertion – a sizable length of DNA is inserted into a gene 3. deletion – segments of a gene are lost

3. Insertions and deletions are called frameshift mutations because they shift the “reading frame” of the genetic content. For example: The fat cat ate the hat. Insertion: The afatca tat eth eha t. The fat cat ate the hat. Deletion: The fat atatetheh at.

4. Effects of Mutations Most mutations have little or no effect, for example, a substitution may affect only a single amino acid and usually has no effect at all. Insertions and deletions which are frameshift mutations can change every amino acid that follows the point of mutation and therefore can have dramatic effects on the organism.

5. Some mutations produce beneficial variations that allow an organism to better adapt to its environment. Genetic material can be altered by: 1. natural or artificial events 2. environmental conditions 3. errors in replication 4. mutagens – chemical or physical agents in the environment that cause mutations, ex: ultraviolet light

6. Are mutations always harmful? • No! Some can be beneficial, or have no effect at all. • Mutations that are harmful result in the production of different proteins. • Mutations in gamete cells are passed on to offspring, therefore, they are more significant than a mutation that occurs in a body cell.