Mutations

Mutations Mutations are errors or mistakes made in the DNA sequence. Some mutations are harmful Some have no effect (neutral) Some could be beneficial. Mutations range in size from a single DNA building block (DNA base) to a large segment of a chromosome.

How do Mutations Occur? Gene mutations occur in two ways: Germline- they can be inherited from a parent (called germline mutations, because they are present in the egg and sperm cells, which are also called germ cells).

Mutations Acquired mutations- occur in the DNA of a cell at some point during a person’s life. These changes can be caused by environmental factors such as ultraviolet radiation from the sun, or can occur if a mistake is made as DNA copies itself during cell division. Acquired mutations in somatic cells cannot be passed on to the next generation.

Types of Mutations Substitution: the replacement of one base in a DNA sequence by another base. The fat cat ate the rat The fat hat ate the rat This may change the amino acid and alter the protein

Types of mutations Insertion: The placement of an extra nucleotide or group of nucleotides in a DNA sequence. The fat cat ate the rat The fat hca tat eth era t Inversion: a piece of DNA breaks off and reattaches in the reverse order. The fat tac ate the rat

Deletion: The elimination of a base or group of bases from a DNA sequence. The fat cat ate the rat The fat ate the rat

Types of Mutations Translocations: Translocations are the transfer of a piece of one chromosome to a nonhomologous chromosome. Translocations are often reciprocal; that is, the two nonhomologues swap segments.

Changes in Chromosomes http://highered.mcgraw-hill.com/sites/0035456775/student_view0/chapter10/changes_in_chromosome_structure.html