MITOCHONDRIAL PHENOTYPES AND GENOTYPES IN YEAST

摘要

Three projects were continued during the year and definitive data were collected in each case, (l) Mitochondrial polysomes in isolated organelle prep¬arations were identified as sites of protein synthesis. The individual ribosomes of the polysomal aggregates are held together by a strand of messenger RNA, which guides the translation into particular proteins. These proteins were of comparable molecular weight to those described by others for yeast adapting to oxygen, while our system involved respiratory adaptation during glucose derepression. (2) The DNA molecules of yeast mitochondria replicate according to a Cairns-type mode and not according to a "rolling circle" model. The replicating molecules were of var¬ied contour length, thus substantiating their reality and casting further doubt on the claim by Borst that all yeast mitochondrial DNA is 25-26 urn long. (3) During our investigation of mitochondrial biogenesis we discovered that all the separate profiles of a yeast cell actually constitute sections through a single giant mito¬chondrion.