Cellular infrastructure and metabolic organization.

Publisher Summary This chapter focuses on the suborganelle cytoplasm of animal cells. Cytoplasmic organization is much more extensive than the usual paradigm of cell structure and function. More or less spatially independent organelles are conventionally believed to be embedded in a viscous, highly concentrated, homogeneous solution commonly referred to as the cytosol which has also been considered to contain many of the enzymes of intermediary metabolism, the soluble enzymes. Cytosol was coined essentially as the 105,000 g supernatant obtained from centrifugation of homogenates. However, it soon was used to describe the volume among cytoplasmic structures in intact cells, and the majority of contemporary biologists often equate the in vitro and in vivo cytosols. Cytologists of the early 20th century recognized and usually emphasized the gel nature of cytoplasm. Much was made of sol-gel transformations in certain cellular (cytoplasmic) properties, but little connection was made during that period between the structure of cytoplasm and the metabolism that took place.