Figure 2-1. The eucaryotic
(8) Lysosomes. Contains digestive enzymes that break down large
molecules into smaller nutrients that can be oxidized by the mitochondria.
(9) Endoplasmic reticulum. Contains many ribosome's that synthesize
enzymes and other proteins
(10) Golgi apparatus. Accumulates proteins and enzymes and conveys
some of them to the cell membrane for secretion. Some of the other enzymes are
encased in lysosomes.
c. Prokaryotic Cell Components. Although structurally different and less
complex than the eucaryotic cells, procaryotes (figure 2-2) still perform most of the
same functions. The nuclear genetic material (DNA) consists of a single, circular,
threadlike chromosome. It is not enclosed within a nuclear membrane, but is distributed
in masses throughout the cytoplasm. Another striking difference between the
eucaryotic and prokaryotic cells is that the cytoplasm of procaryotes does not contain
membrane-enclosed bodies such as mitochondria, endoplasmic reticulum, or golgi
apparatus. Some procaryotes possess mesosomes that are somewhat similar to
mitochondria in their function. Ribosomes (sites of protein synthesis) are distributed
throughout the cytoplasm. With few exceptions, the prokaryotic cell is surrounded by a
cell wall. These cell walls are not made of cellulose or polysaccharides; but contain
peptidoglycan, which is found only in procaryotes. Cell division is by binary fission
rather than mitosis or meiosis.