Laboratory Notes for BIO 1003

© 30 August 1999, John H. Wahlert & Mary Jean Holland


Gene Problems in Transcription and Translation

  1. For the segment of a strand of DNA whose nucleotide sequence is shown below write the appropriate nucleotide sequence in the mRNA (transcription).

    T A C C G A G G G C T T A A A A T G A T T

     

    Genetic Code Table: mRNA Codon:Amino Acid
    First
    Letter
    Second
    Letter
    Third
    Letter
      U C A G  
    U phenylalanine serine tyrosine cysteine U
    phenylalanine serine tyrosine cysteine C
    leucine serine stop stop A
    leucine serine stop tryptophan G
    C leucine proline histidine arginine U
    leucine proline histidine arginine C
    leucine proline glutamine arginine A
    leucine proline glutamine arginine G
    A isoleucine threonine asparagine serine U
    isoleucine threonine asparagine serine C
    isoleucine threonine lysine arginine A
    (start)

    methionine
    threonine lysine arginine G
    G valine alanine aspartate glycine U
    valine alanine aspartate glycine C
    valine alanine glutamate glycine A
    valine alanine glutamate glycine G

     

  2. Write the six different mRNA codons for serine.

     

  3. How many codons are there for valine? for asparagine? for tryptophan?

     

  4. Why must every mRNA begin with the codon AUG?

     

  5. Write the three different mRNA termination (STOP) codons.

     

  6. These six possible codons for arginine might appear in a molecule of mRNA. For each one write the anticodon on the tRNA molecule (the "taxi") that will carry arginine to the ribosome when that particular codon is read.

    CodonsAnticodons
    C G U 
    C G C 
    C G A 
    C G G 
    A G A 
    A G G 

     

  7. For the sequence of nucleotides in the mRNA molecule shown below, write the appropriate amino acid sequence in the protein synthesized when this message is read by the ribosome (translation).

    A U G G G A U U U C U C G G A A A A U U C A G G U A A

     

  8. The nucleotide sequence of a gene (segment of a strand of DNA) coding for a protein six amino acids long is given below:

    T A C G T A C T G C G C A A G A A T A T C

    1. Write the appropriate sequence of nucleotides in the mRNA.

       

    2. Write the appropriate amino acid sequence in the protein encoded by this gene.

       

    3. Write the anticodons for the tRNAs bringing amino acids to the ribosome for the synthesis of this protein.

       

    4. Compare the anticodons with the original DNA sequence. Do you notice any similarity?

       

    For questions 914. Five transformations of an original sequence of nucleotides in one half of an original DNA molecule are given (a-e). The original DNA reads:

    T A C C G C A A T G C T T G A G G C

    1. A T G G C G T T A C G A A C T C C G

    2. A U G G C G U U A C G A A C U C C G

    3. A U G U U A C C G

    4. T A C C G C A A A G C T T G A G G C

    5. T A C G C A A T G C T T G A G G C

     

  9. Which of the above is replication by base pairing with the original DNA?

     

  10. Which of the above is a mutation by base substitution in the original DNA?

     

  11. Which of the above is a mutation by nucleotide deletion from the original DNA that will cause a frame shift?

     

  12. Which of the above is a primary transcript of mRNA from the original DNA?

     

  13. Which of the above is mRNA, transcribed from the original DNA, that has had the introns removed?

     

  14. Which mutation will have the greatest phenotypic effect? Explain your answer.

     

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    Last updated 6 May 1999 (JHW)