self repair biomolecules
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Answer:
Many organisms and tissues display the ability to heal and regenerate as needed for normal physiology and with pathogenesis. However, these repair activities can also be observed at the single cell level. The physical and molecular mechanisms by which a cell can heal membrane ruptures and rebuild damaged or missing cellular structures remain poorly understood. This review presents current understanding in wound healing and regeneration as two distinct aspects of cellular self-repair by examining a few model organisms that have displayed robust repair capacity, including Xenopus oocytes, Chlamydomonas, and Stentor coeruleus. While many open questions remain, understanding how cells repair themselves is important for our mechanistic understanding of cell biology. It also holds the potential for new applications and therapeutic approaches for treating human disease.
Introduction
Cells are generally soft, squishy, and easily damaged. However, many can repair themselves after being punctured, torn, or even ripped in half when damaged due to the normal wear-and-tear of normal physiology or as a result of injury or pathology. A cell is like a spacecraft: when it is punctured, cytoplasm spills out like oxygen escaping from a damaged space module. Like Apollo 13, a damaged cell cannot rely on anyone to fix it. It must repair itself, first by stopping the loss of cytoplasm, and then regenerate by rebuilding structures that were damaged or lost. Understanding how they repair and regenerate themselves could guide treatments for conditions involving cellular damage.
A standard question we ask students is to define what it means to be alive. This is surprisingly hard to do in a precise way, but surely one of the remarkable features of living systems that distinguishes them from human-made machines is their ability to heal and repair themselves. At the multi-cellular level, repair and regeneration are effected by generating new cells to replace the ones that were lost. This type of repair thus ends up being a direct consequence of another basic feature of living systems – the ability of a cell to reproduce itself. No additional processes need to be invoked beyond cell division. At the single-cell level, it is much less obvious how self-repair is accomplished.
In this review, we will distinguish wound healing from regeneration as two aspects of self-repair which serve distinct purposes, and will discuss each aspect separately. Wound healing is the process that stops further loss of material, in much the same way a blood clot stops further loss of blood. Regeneration, on the other hand, is the process by which the cell specifically re-builds and replaces the missing components (organelles, plasma membrane, cytoplasm, etc.) after the wound has been stabilized. Some cells can heal wounds but cannot regenerate. For example, if the the giant unicellular ciliate Bursaria is cut in half, the halves heal their surfaces and live, but they lose all their cortical structures, become spherical, encyst, and then re-develop a new cortical pattern from scratch (1). We contrast such cases from cells which are able to detect missing structures and specifically regenerate the pieces that were missing or damaged.
Examples of self-repairing cells
Many cell types can heal wounds and regenerate missing structures (Figure 1). Neurons are sometimes able to repair and regenerate damaged axons (2, 3), which is important because they do not proliferate. Cardiac myocytes routinely suffer mechanical wounding as the heart beats, and are able to survive and heal membrane ruptures (4, 5).
Explanation:
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Explanation:
Spontaneous self-assemblies of biomolecules can generate geometrical patterns. Our findings provide an insight into the mechanism of self-assembled ring pattern generation by human serum albumin (HSA). The self-assembly is a process guided by kinetic and thermodynamic parameters. The generated protein ring patterns display a behavior which is geometrically related to a n-simplex model and is explained through thermodynamics and chemical kinetics.
Keywords: protein self-assembly; Pascal’s triangle; n-simplex; geometric pattern; thermodynamics; kinetics