Date Approved

2012

Degree Type

Open Access Senior Honors Thesis

Department or School

Biology

First Advisor

Anne Casper

Second Advisor

Gary Hannan

Abstract

Many diseases such as autism, epilepsy, mental retardation, Parkinson 's disease, and cancers, can result from a type of genetic variation known as copy number variations (CNV). CNVs are segments of DNA that exist in multiple copies o f the genome, with variation between individuals in the number of copies. They may be formed when mistakes in DNA replication occur while the cell is grown under stressful conditions. We hypothesize that when the yeast cells are under replication stress, such as low levels of DNA polymerase, the cell will develop CNVs in the location of a known chromosomal fragile site. Using yeast, we manipulated its genome to create a marker which enabled us to observe the frequency of

DNA deletions and duplications near the fragile site. In cells with low level s of DNA polymerase, we observed deletion of the marker i n 0.557% of cells, duplication of the marker in 18.2% of cells, and three copies of t he marker in 0.041% of cells. Cells with normal polymerase did not have deletion or triplication of the marker, but had a similar level of duplication. While the data is only preliminary at this stage, the experimental system created serves as a stepping stone in further studies of CNV formation at chromosomal fragile sites.

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