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Unformatted text preview: . While the order of genes is the same, some distances determined
by these two measurements differ. har06584_refA_001-020 4 11/4/06 10:09 AM Page 4 Reference A Saccharomyces cerevisiae: Genetic Portrait of a Yeast Determining the Number of Genes in Yeast
16,000 14,000 12,000 Number of ORFs 10,000 8000 6000 4000
10 0 Number of annotated ORFs The Human Genome Project, completed in 2001, has
taught researchers that estimating the number of proteincoding genes in an organism is surprisingly difﬁcult.
Before completion of the project, human geneticists
estimated the existence of 100,000 human genes, about
16 times as many as were predicted for yeast. After the sequence became available, the estimate dropped to about
20,000–30,000 human genes or 3–5 times as many as in
yeast. The estimate of the number of human genes will undoubtedly undergo repeated revisions in the coming years.
In yeast, there is still debate over the number of proteincoding genes. To predict the number of genes that code for
proteins from the number of open reading frames (ORFs)
identiﬁed in the yeast genomic DNA sequence, an arbitrary
cutoff of 100 amino acids was established as the minimum
length of a functional open reading frame. The...
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This note was uploaded on 10/03/2013 for the course BI 206 taught by Professor Celenza during the Spring '08 term at BU.
- Spring '08