Molecular Genetics

Facts

• Human cells were cultured in the presence of low concentrations of the antibiotic chloramphenicol. After prolonged passage, cell lines resistant to chloramphenicol were obtained.
• Cells from the resistant lines were enucleated. The anuclear cells were fused to cells from the original chloramphenicol sensitive cell line. The fusion products were selected in chloramphenicol containing medium. Cells grew.
• Mitochondria were isolated from cells of the resistant line. Isolated mitochondria were microinjected into chloramphenicol sensistive cells. The microinjected cells grew in chloramphenicol-containing medium .

Interpretations

• Some heritable traits, such as chloramphenicol resistance, are cytoplasmically inherited. Inheritance should not follow Mendel's laws.
• Cytoplasmic inheritance in human cells is due (at least in part) to mitochondria.
• Mitochondria must contain genetic material.

Further information

• Mitochondria and chloroplasts have their own genomes.
• Cytoplasmic inheritance (rev) can be maternal or biparental.
• A variety of mechanisms are responsible for maternal inheritance (rev).
• Organelle genetics is the genetics of populations.
• Replication of organelle genomes differs from that of nuclear genomes.
• Mechanisms for segregation of organelles may exist.
• Defects in organelle genomes are associated with hereditary diseases.
• Organelles arose by endosymbiosis.

This is page 137 of Molecular Genetics by Ulrich Melcher, © 1997, 1998, 2003