What are lysosomes and their functions?
A digestive structure found within virtually all types of animal cells. Lysosome sizes, microscopic appearances, and other properties vary among different cell types and circumstances owing, in part, to differences in their functions and states. Typical lysosomes are roughly spherical or elongate bodies with largest dimensions of 0.1–1 micrometer or greater; tens to hundreds are present in a single cell. Each lysosome is bounded by a membrane and contains several dozen different species of digestive enzymes, each of which can sever particular chemical bonds found in natural materials. Most lysosomal enzymes function best in an acid environment. This acidification is accomplished by a proton pump, built into the membrane surrounding the lysosome, which effects the transport of hydrogen ions into the lysosomes. Lysosomes digest materials taken into the cell from the outside (a process known as heterophagy) as well as other materials that originate in the cell’s own cytoplasm (autophagy).
