Gated channels allow specific ions to pass across the membrane. Carriers facilitate the passage of molecules across the membrane and often use energy. Receptor-mediated endocytosis allows cells to internalize specific small molecules. Protozoa and phagocytes internalize bacteria and debris by phagocytosis. Exocytosis is used to expel material. Secreted proteins are translocated across the membrane of the endoplasmic reticulum as they are being made.
■ How does a cell bring in ligands?
■ How is the formation of an endocytic vesicle different from that of a phagosome?
■ How might a bacterium resist the killing effects of a phagolysosome?
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Our internal organs, the colon, liver and intestines, help our bodies eliminate toxic and harmful matter from our bloodstreams and tissues. Often, our systems become overloaded with waste. The very air we breathe, and all of its pollutants, build up in our bodies. Today’s over processed foods and environmental pollutants can easily overwhelm our delicate systems and cause toxic matter to build up in our bodies.