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Students compare the effect of several different types of mutations in DNA, including nucleotide substitution, nucleotide insertion, and nucleotide deletion.
Students will be able to:
In this activity students can edit a DNA nucleotide sequence and observe how it will affect the sequence of amino acids in the protein and the shape of the resulting protein. With this notion, they can generate different mutations. For example, by inserting or deleting a nucleotide, they create a frameshifting mutation, and compare the effect with less dramatic substitution mutations. Students reinforce the idea that frameshift mutations typically lead to multiple changes in the amino acid sequence and the appearance of a non-functional protein. If the protein were essential for the living cell, such a mutation would be lethal.
A mathematical codon exercise can help students figure out the redundancy concept of the codons. Ask your students to figure out how many three-letter "words," such as AAA or ATA etc. can be made from four letters A, T, C, and G. To start, you might help them discover for themselves that there are 16 possible "words" beginning with A. The same must be true for words beginning with G, T, and C, for a total of 16+16+16+16 or 64 different words.
Mutations in DNA can result in changes in the sequence of amino acids of a protein (its primary structure). Mutations may lead to changes in protein structure, in the way a protein functions, and can become the molecular cause of illness. Due to the redundancy of the genetic code, many changes have no effect.
Additional Related Concepts
An activity that looks specifically at the molecular basis for Sickle Cell Anemia can be found at