Mutations Add to Table of Contents – p. 14

What Are Mutations? Changes in the nucleotide sequence of DNA Results in a change in the amino acid sequence of a protein Mutagen: something that causes a mutation X-rays, Chemicals, & UV radiation are examples of mutagens

Are Mutations Helpful or Harmful? Mutations happen regularly Almost all mutations are neutral Many mutations are repaired by enzymes

Are Mutations Helpful or Harmful? Some types of skin cancers and leukemia result from mutations Some mutations may improve an organism’s survival (beneficial)

Types of Mutations

Gene Mutations Change in the nucleotide sequence of a gene May only involve a single nucleotide May be due to copying errors, chemicals, viruses, etc.

Gene Mutations Include: Point Insertion Deletion

Point Mutation One nucleotide is substituted for another Also known as substitution

Point Mutation Sickle Cell disease is the result of one nucleotide substitution Occurs in the hemoglobin gene

Frameshift Involves insertion or deletion of a nucleotide Affects end polypeptide much more than a simple substitution

Insertion A nucleotide is added into the DNA sequence THE CAT ATE THE RAT  THE CAT TAT ETH ERA T

Deletion A nucleotide is deleted THE CAT ATE THE RAT  THE CAT TET HER AT

Chromosome Mutations May Involve: Changing the structure of a chromosome The loss or gain of part of a chromosome Include: Inversion Duplication Translocation

Inversion Chromosome segment breaks off, flips around backwards, and reattaches

Duplication Occurs when a gene sequence is repeated

Translocation Involves two chromosomes that aren’t homologous (do not match together) Part of one chromosome is transferred to another chromosome

Nondisjunction Failure of chromosomes to separate during meiosis Can cause a person to have too many or too few chromosomes

Chromosome Mutation Animation

Amino Acid Sequence Changed

Gene Mutation Animation

Identify the type of mutation given the original DNA sequence: Identify the type of mutation given the original DNA sequence: ACGTACGCA 1.  ACGTCCGCA - point 2.  ACGTAGCA - deletion 3.  ACGTACAGCA - insertion 4.  ACGCATGCA - inversion 5.  ACGACGTACGCA - duplication 6.  TCGTACGCA – point 7.  ACATGCGCA - inversion