Microbodies

Besides the large, familiar organelles, the cytoplasm of both plant and animal cells contains many extremely tiny, membrane-bound sacs called microbodies. Each one is a minute vesicle bounded by a single membrane, and packed inside it are a variety of enzymes. Because they are so small, microbodies are easily overlooked under an ordinary microscope, yet they are a normal and regular feature of eukaryotic cells.

Their defining features are straightforward:

• They are membrane-bound, so the enzyme-driven reactions they carry out are kept enclosed and separated from the rest of the cytoplasm.
• They are minute in size — much smaller than organelles such as mitochondria or plastids.
• They contain various enzymes, the exact set differing from one microbody to another.
• They are found in both plant cells and animal cells. …