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MUTATIONS Changes in DNA that affect genetic information

What Are Mutations?  Changes in the nucleotide sequence of DNA  May occur in somatic cells (aren’t passed to offspring)  May occur in gametes (eggs & sperm) and be passed to offspring

Are Mutations Helpful or Harmful?  Mutations happen regularly  Almost all mutations are neutral  Chemicals & UV radiation cause mutations  Many mutations are repaired by enzymes

Are Mutations Helpful or Harmful?  Some type of skin cancers and leukemia result from somatic 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.

Types of Gene Mutations  Include:  Point Mutations  Substitutions  Insertions  Deletions  Frameshift

Gene Mutations  Point Mutations – changes in one or a few nucleotides  Substitution  THE FAT CAT ATE THE RAT  THE FAT HAT ATE THE RAT  Insertion  THE FAT CAT ATE THE RAT  THE FAT CAT XLW ATE THE RAT  Deletion  THE FAT CAT ATE THE RAT  THE FAT ATE THE RAT

Gene Mutations  Frameshift Mutations – shifts the reading frame of the genetic message so that the protein may not be able to perform its function.  Insertion  THE FAT CAT ATE THE RAT  THE FAT HCA TAT ETH ERA T  Deletion  THE FAT CAT ATE THE RAT  TEF ATC ATA TET GER AT H H

Amino Acid Sequence Changed

Gene Mutation Animation

Chromosome Mutations  Changes in number and structure of entire chromosomes  Original Chromosome ABC * DEF  DeletionAC * DEF  DuplicationABBC * DEF  InversionAED * CBF  TranslocationABC * JKL GHI * DEF

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

Duplication  Occurs when a gene sequence is repeated

Inversion  Chromosome segment breaks off  Segment flips around backwards  Segment re-attaches

Translocation  Chromosome segment breaks off.  Segment attaches to another segment. segment.

Chromosome Mutation Animation

Significance of Mutations Most are neutralMost are neutral Eye colorEye color Birth marksBirth marks Some are harmfulSome are harmful Sickle Cell AnemiaSickle Cell Anemia Down SyndromeDown Syndrome Some are beneficialSome are beneficial Sickle Cell Anemia to MalariaSickle Cell Anemia to Malaria Immunity to HIVImmunity to HIV

What Causes Mutations?  There are two ways in which DNA can become mutated:  Mutations can be inherited.  Parent to child  Mutations can be acquired.  Environmental damage  Mistakes when DNA is copied