BIOLOGY: CH14 GENES IN ACTION DNA MUTATIONS NAME ______________________ Mutations are changes in the genetic sequence. Some can have major effects and some may have none. Some mutations are simple changes to the DNA sequence and some are major changes to entire pieces of chromosomes. Lets look at simple changes to the gene sequence and their effects Using the DNA sequence that follows please list the complimentary mRNA strand, and the amino acid sequence or protein that will be produced. Please Use the 3 letter abbreviations for the amino acids DNA sequence TAC GGG ACA GAG CGT TGT GAC CCC AAA TTT TTA TTA TCT mRNA sequence ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ AMINO ACID Sequence ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ Assume this is the normal sequence of a functional gene and its functional protein. A point mutation is a single change to a DNA sequence and it may be identified as a: silent mutation, missense mutation, Frameshift mutation, Nonsense Mutation or Amino Acid Substitution or deletion Silent Mutation DNA sequence TAC GGG ACA GAG CGT TGG GAC CCC AAA TTT TTA TTA TCT mRNA sequence ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ AMINO ACID Sequence ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ 1. Identify the nucleotide which has changed and how it affected the proteins amino acid sequence. 2. Define a Silent Mutation Missense Mutation DNA sequence TAC GGG ACA GGG CGT TGT GAC CCC AAA TTT TTA TTA TCT mRNA sequence ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ AMINO ACID Sequence ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ 3. Identify the nucleotide which has changed and how it affected the proteins amino acid sequence. 4. Define a Missense Mutation 5. Does it matter which letter (first second or third) is changed? Why? Frameshift Mutation: Insertion DNA sequence TAC GGG ACA GAG CGT TGT GGA CCC CAA ATT TTT ATT ATC T mRNA sequence AMINO ACID Sequenc ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ 6. Identify the nucleotide which has changed and how it affected the proteins amino acid sequence. 7. Define a Frameshift Mutation with nucleotide insertion Frameshift Mutation: Deletion DNA sequence TAC GGG ACA GAG CGT TGT ACC CCA AAT TTT TAT TAT CT? mRNA sequence AMINO ACID Sequenc ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ 8. Identify the nucleotide which has changed and how it affected the proteins amino acid sequence. 9. Define a Frameshift Mutation with nucleotide deletion Nonsense Mutation DNA sequence TAC GGG ACA GAG CGT TCT GAC CCC AAA TTT TTA TTA TCT mRNA sequence AMINO ACID Sequence ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ ____ 10. Identify the nucleotide which has changed and how it affected the proteins amino acid sequence. 11. Define a Nonsense Mutation 12. What happens when a stop codon occurs? AMINO ACID SUBSTITUTION/DELETION 11. What would happen to a protein if an extra amino acid was added or deleted? Would the Protein still be functional? Explain
