Mutations Mutations are random rare changes in genetic

Mutations

�Mutations are random, rare changes in genetic material that can occur during DNA replication ◦ If a mutation occurs in part of DNA that codes for a gene, there could be a change in the characteristics of that organism ◦ Mutations can also occur in whole Chromosomes Mutations

�Mutations that occur in somatic cells are NOT passed to offspring �Mutations that occur in gametes (sperm and eggs) ARE passed to offspring �Spiderman experienced what type of mutation?

� 5 Types of Chromosome Mutations ◦ Deletion ◦ Inversion ◦ Translocation ◦ Nondisjunction ◦ Duplication Chromosome Mutations

�Due to breakage �A piece of a chromosome is lost Deletion

�Chromosome segment breaks off �Segment flips around backwards �Segment reattaches Inversion

�Occurs when a gene sequence is repeated Duplication

�Involves two chromosomes that are NOT homologous �Part of one chromosome is transferred to another chromosome Translocation

�Failure of chromosomes to separate during Meiosis �Causes gamete to have too many or too few chromosomes Nondisjunction

Chromosome Mutation Animation

�Change in the nucleotide sequence of a gene �May only involve a single nucleotide ◦ Point mutation �May be due to replication errors, chemicals, viruses, radioactive spiders, etc. Gene Mutations

�Change of a single nucleotide �Includes the deletion, insertion, or substitution of ONE nucleotide in a gene Sickle Cell Disease is the result of one nucleotide Substitution that changed one amino acid �Occurs in the Hemoglobin gene Point Mutations

�Substitution- one base pair is exchanged for another ◦ Can cause a change in a codon, which DOES NOT result in a change in the amino acid coded for by that codon ◦ This type of mutation is called a Silent Mutation because there is no change in the type of protein that is produced Types of Gene Mutations

�Inserting or Deleting one or more nucleotides �Changes the “reading frame” of the gene �Proteins built incorrectly ◦ Original: ◦ The fat cat ate the wee rat. ◦ Frame Shift (“a” added): ◦ The fat caa tet hew eer at. Frameshift Mutation

�Insertion- an extra base pair is inserted into a new place in the DNA Types of Gene Mutations

�Deletion- a base pair or section of DNA is lost or deleted 3 Types of Mutations

Amino Acid Sequence Changed

Gene Mutation Animation

�A Mutagenic Factor- anything that can cause a change in DNA ◦ X-Rays and UV rays (high energy radiation) can cause breaks in DNA that are not easily repaired ◦ Chemicals can cause substitutions and changes in DNA that affect the order of amino acids in a polypeptide �Substances that cause changes in DNA leading to cancer are called carcinogens Mutagenic Factors