Sometimes replication, transcription and translation don’t go as planned! Replication, Transcription, and Translation errors result in mutations. A mutation is any change in the DNA of an organism.

Truths about mutations! MOST mutations are minor. Many mutations are harmful. Some mutations are lethal. Very few mutations are helpful.

Mutations can occur as… Germ Mutations mutations in gametes Somatic Mutations mutations in body cells

Two Types of Mutations Chromosome Mutations 2. Gene Mutations

Types of Mutations within chromosomes Deletion Inversion Translocation Nondisjunction

Deletion a piece of a chromosome breaks off and is lost

Inversion a piece of a chromosome breaks off and reattaches itself in reverse order

Translocation a broken piece attaches to a nonhomologous chromosome

Nondisjunction a pair of chromosomes fail to separate during Anaphase I of meiotic cell division results in trisomy or monosomy Trisomy = three of one kind in a diploid cell Monosomy = one of one kind in a diploid cell

Types of Gene Mutations Point Frame-shift

Point a change in a single nitrogen base in DNA Often referred to as a “nonsense” mutation

Frameshift the addition or deletion of a nitrogen base, causing a shift in the sequence of codons the amino acid sequence is nonsense, coding for all the wrong amino acids

What causes a mutation? Anything that causes a mutation is called a mutagen Environmental mutagens include: Ultraviolet radiation Tars from tobacco Asbestos