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Unformatted text preview: he genes. with the GAL genes that encode enzymes active in the
transport and degradation of galactose, the clustered genes
are usually transcribed into mRNA from separate, divergent transcriptional promoters. Gene Arrangement The Proportion of Repeated Sequences
Is Low in Yeast The bulk of the yeast genome is composed of unique, nonreiterated DNA sequences. Approximately 75% of the
genome is transcribed into RNAs; and most of these RNAs
are nonoverlapping. On average, there is one yeast gene for
every 1.5–2.0 kb of DNA. Genes related in function are often coregulated, but they are not usually clustered according to function or organized like bacterial operons. In the
rare instances where functional clustering does occur, as Although the yeast genome does contain some reiterated
DNA sequences, the proportion of the genome devoted to
reiterated DNA is much lower than in multicellular eukaryotes. The 100–200 copies of rDNA rank highest in abundance. Other repeated sequences of note include tRNA
genes, the subtelomeric repeats, which are reiterated one to
four times near the ends of the chromosomes; and a complex family of retrotransposons called Ty elements, of har06584_refA_001-020 11/4/06 10:09 AM Page...
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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