membranbundne

Membranbundne is a term used in cell biology to describe cellular structures or compartments that are enclosed by a lipid bilayer, separating their interior from the surrounding cytosol. This membrane boundary allows the formation of distinct chemical environments and regulates the passage of substances.

In eukaryotic cells, most organelles are membranbundne. Common examples include the nucleus, mitochondria and chloroplasts (both typically enclosed by two membranes), as well as single-membrane organelles such as the endoplasmic reticulum, Golgi apparatus, lysosomes, peroxisomes, and various vesicles and vacuoles. By contrast, many large protein complexes and ribosomes are not membranbundne and reside in the cytosol.

The presence of membranes enables compartmentalization, enabling specialized metabolism, ion gradients, and controlled trafficking of molecules. Membrane-bound organelles can maintain distinct pH levels, enzymatic conditions, and lipid compositions, supporting complex cellular processes such as energy production, protein synthesis, and waste processing. Transport between compartments is managed by vesicles, membrane proteins, and fusion events, allowing selective exchange and communication.

Biogenesis and dynamics of membranbundne structures involve lipid synthesis, membrane remodeling, and vesicular trafficking. They grow and divide through processes like membrane budding, fission, and fusion, and can be degraded or recycled via autophagy or turnover pathways.

Defects in membrane integrity or trafficking can contribute to diseases, including mitochondrial disorders, lysosomal storage diseases, and neurodegenerative conditions. Evolutionarily, several membranbundne organelles (notably mitochondria and chloroplasts) are thought to arise from ancient endosymbiotic events.