Compare lysosomes and peroxisomes.

Lysosomes have been well known since they were described by Christian de Duve in the early 1950s. They are small, usually oval organelles that contain powerful digestive enzymes in an acidic environment. The membrane surrounding the organelle is single and functions to maintain a high degree of internal acidity. The potentially destructive enzymes of the lysosome are probably synthesized by ribosomes, which then pass the enzymes through the endoplasmic reticulum to the Golgi apparatus. The lysosomes appear to bud off the Golgi apparatus in some cells. Lysosomes play a role in cellular digestion. They may fuse with other bodies within the cell to effect the digestion of a variety of materials. In phagocytosing white cells, such as the mammalian neutrophil, lysosomes bring about the breakdown of bacteria and other foreign material engulfed by the cell. Lysosomes are also involved in the destruction of cells that have been injured or are no longer viable. During the development of the frog, the long tail, which is a feature of the tadpole, is resorbed through the action of lysosomes and its molecules used for newly emergent structures. In the thyroid gland, the lysosomes act on thyroglobulin to produce the actual active hormone thyroxin. As might be expected, the degradative enzymes of lysosomes work best at low (acid) pH.
Peroxisomes, originally called microbodies, are small organelles bounded by a single membrane and usually contain a fine granular matrix. In plants, they play a significant role in photorespiration. Those peroxisomes that participate in the metabolic cycle involving the formation of glyoxylate have been termed glyoxysomes. All of the peroxisomes thus far studied contain enzymes for oxidizing materials, in contrast to the hydrolytic (digestive) enzymes of the lysosomes. Generally, hydrogen peroxide (H2O2) is produced during these oxidations, but the enzyme catalase quickly decomposes the H2O2 to prevent a harmful buildup of peroxides. The precise steps by which peroxisomes are assembled are not completely clear, but they appear to be closely associated with the endoplasmic reticulum.

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