Lysosomes are organelles within the cell that prevent the accumulation of malfunctioning proteins by continuously breaking them down into their constituent amino acids which are, in turn, used to build new proteins. This process involves enzymes and increases the efficiency of cells in two ways: (1) by eliminating the need for complex waste management systems and (2) by providing the cells with new building blocks that don’t need to be “purchased” externally.
Lysosomes: In the cell, a waste protein (A) is taken up by a lysosome (B). In a process called proteolysis, the waste protein is broken down into the useful building block amino acids (C). Artist: Emily Harrington. Copyright: All rights reserved. See gallery for details.
“The other main degradation system is the lysosome, which contains multiple proteases [enzymes] and accounts for ~20% of protein turnover in cells. Lysosomes mainly degrade organelles and membrane proteins. Cytoplasmic proteins can also be degraded through autophagy, a process in which organelles and bulk cytoplasm are enveloped in double membranes and then delivered to lysosomes.” (Bingol and Sheng 2011: 22)