Final answer:
A thick protective coating that protects the bacteria's genetic material and cytoplasm is called a capsule.
Step-by-step explanation:
A capsule is a thick protective layer surrounding the genetic material and cytoplasm of bacteria. Composed of polysaccharides or proteins, the capsule serves as a defense mechanism against the host's immune system. It helps bacteria evade phagocytosis, the engulfing of microorganisms by immune cells.
The capsule provides a physical barrier and inhibits the recognition of bacterial surfaces by immune cells. This protective feature enhances the bacteria's survival in harsh environments and facilitates the establishment of infections. Capsules are a significant virulence factor in pathogenic bacteria, contributing to their ability to cause diseases by promoting bacterial evasion of host defenses.