Mutations

ex: Chemicals, high temperatures, UV light, radiation General Information  Mutation: Mistake in the DNA.  Can be random or caused by mutagens. ex: Chemicals, high temperatures, UV light, radiation  Body Cell Mutations-only effect person  Sex Cell Mutations- Passed on to offspring.

How Do we protect the dna from mutations? Cells have “proof reading” proteins that constantly check the DNA and fix errors, so most are corrected. However, some slip through the cracks…

Recall: Triplet Code – codons Ribosome reads in codons, or the triple code.

Examples: Original DNA Code: THE DOG BIT THE CAT

Substitution - Replace just one letter THE DOG BIT THE CAT THE DOG BIT THE CAR

Deletion: Delete just one letter (T from “bit”) THE DOG BIT THE CAT THE DOG BIT HEC AT

Insertion - Add just one letter (E in “dog”) THE DOG BIT THE CAT THE DOE GBI TTH ECA T

Frameshift Mutation: Changes the reading frame of the DNA Frameshift Mutation: Changes the reading frame of the DNA. (shifts the codons) Ex: Insertion, Deletion Ex: Normal vs. Mutation DNA: TAC GAT TAG DNA: TAA CGA TTA C mRNA: AUG CUA AUC RNA: AUU GCU AAU C Protein: Met-Leu-Ile Protein: Ile-Ala-Asn Reading Frame = Triplet Code

Duplication Mutation- Part of the DNA is copied twice or more. Ex: Normal vs. Mutation DNA: TAC GAT TAG DNA: TAC GAT GAT TAG mRNA: AUG CUA AUC RNA: AUG CUA CUA AUC Protein: Met-Leu-Ile Protein: Met-Leu-Leu-Ile

Point Mutation- Change in one nitrogenous base. Sometimes this will not alter the amino acid sequence because of the duplicates in the codons that code for an amino acid. Change No Change DNA: AAA  ATA DNA: TAATAG RNA: UUU  UAU RNA: AUU AUC Protein: Phe  Tyr Protein: IleIle