Question

8. (There are three main classes of plasmid vector used in S. cerevisiae: YEp, YCp and YIp plasmids. a) Which of these would you use in order to find the true complementing gene of a mutant phenotype and why?

b) Which of these would you use in a genetic (chromosomal) mapping study and why?

Answer 1

a) Yesat cemtromeric vector (ycp) vectors mey be used to find out the true complementing gene of a mutant phenotype, since ycp are the shuttle vector and these are considered low copy vectors and incorporate part of an ARS along with part of a centromere sequence (CEN). These vectors replicate as though they are small independent chromosomes and are thus typically found as a single copy. Unlike the ARS vectors, CEN vectors are stable without integration. So that they mey able to complement the mutant phenotype and rescue the wild type.

b) Yeast integrative plasmid (YIp), yeast vectors that rely on integration into the host chromosome for survival and replication, and are usually used when studying the functionality of a gene or when the gene is toxic.

These plasmids lack an ORI and must be integrated directly into the host chromosome via homologous recombination. So they used better for chromosome mapping studies.