Yeast Lab Final Report
This report must be word-processed, and completed individually or as a team.
Answer the following questions for the ADE1 gene:
1. Give the full name of the gene in question, and tell the biochemical reaction that it
catalyzes.
2. What treatment of the yeast in week 1 led to the observed difference in the base
sequence to this gene?
3. Is the ADE1 mutant amino acid sequence different from the wild type? If there are
differences then address the following questions: what amino acid number in the chain is
different? Provide the single letter abbreviation for the name of the amino acid that is
present at that position in the gene from the red yeast. The reading that you did for your
RAP categorized mutations as "nonsense"," missense", "silent", or "frameshift". Which
category does this fit into?
4. Now go to the following link to the NCBI Conserved Domains database
http://www.ncbi.nlm.nih.gov/Structure/cdd/cddsrv.cgi?hslf=1&uid=cd01414&#se
qhrch This page shows the yeast ADE1 protein aligned to the homologous proteins of
other species (humans, chickens, bacteria). Near the top of the page, you will see a
window that looks like this:
If you click on ‘Active Site’, the protein alignments below will have a # above amino
acids known to be involved in the enzyme active site. The same will be true for the ATP
binding site and the substrate binding site of the enzyme, all of which are critical to
enzyme function.
Now scroll down to the lower part of the page that shows the yeast sequence alignment.
It should look like this:
The first protein sequence (10BG_A) is the wild type yeast sequence. The rest are
human, chicken, bacteria, etc. Highly conserved amino acids are indicated in red, while
less conserved are indicated in blue. Locate the amino acid residue that was changed in
your ADE1 gene. Is it part of the active site? Is it involved in ATP binding or substrate
binding? Is it in a highly conserved region of the protein? Looking at the table of
structures of the amino acids provided in your textbooks, describe the difference in the
amino acid that is altered—is it similar to, slightly different, or radically different in
structure from the original amino acid? Now look at the amino acids that the species in
this analysis, including yeast, normally have at that site. What do they all have in
common? Using this information, hypothesize how your mutation is likely to impact the
ability of the Ade1 protein to carry out its function. Is the difference in the amino acid
sequence of the Ade1 protein in the red strain compared to the white strain a reflection of
a difference in the DNA sequence between the ADE1 gene of the red strain compared to
the white strain? Explain your answer.
5. Finally, assume that you are a genetic counselor working with a couple who have both
been shown to be heterozygous for the same mutation in their ADE1 genes. Neither
individual shows any symptoms, but both are concerned that a homozygous child of
theirs might. How would you determine if the mutation in question is likely to be
detrimental to their children?