Mini Lab - Left to Right or Right to Left? Copy

This Mini-Lab is designed to enforce previously learned knowledge of DNA sequencing.  Its use in this lesson is to refresh the students on the importance of interpreting DNA in one direction only.

Teacher Goals

  • To interpret DNA sequences

  • To discover the importance of DNA sequencing

Required Resources

  • Textbooks

    There is usually a chart of the amino acids in every Biology text. I had my students use this chart to aid in coding for amino acids.
     

  • Worksheets
    There should be one worksheet for every student. This will list the DNA sequence they will decode.
     

  • Paper & pencils
    The students were required to write down each step they took during the decoding process.

  • Left to Right or Right to Left?

    I assessed my students based on participation, completion, and correctness of answers.
     

Optional Resources

  • Genetic Wheel 

    Some of my students used a genetic wheel with the amino acides listed. This wheel aids in naming the amino acids.
     

  • Online Genetic Wheel

    A printable, online genetic wheel can be found at this site, provided by San Diego State University.
     

Steps

  1. Procedure

    Assume that a gene contains the following sequence of nucleotides: GACAAGTCCACAATC

  2. Procedure

    Reading from the left to the right, transcribe the gene into a molecule of mRNA.
     

  3. Procedure

    Reading the codons from left to right, translate the mRNA into a polypeptide.
     

  4. Procedure

    Repeat step 3 reading the codon from the right to left.

  5. Analyze and Conclude

    Why did steps 3 & 4 produce different polypeptides?
     

  6. Analyze and Conclude

    Do cells decode nucleotides in one direction only or can they decode them in either direction? Formulate a hypothesis to answer this question.
     

Teacher Notes

  • This lesson takes only about 20 minutes, although some students may require up to 30 minutes (with discussion time included).

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