Question

how do bacteria protect themselves?

Answer 1

Some bacteria have capsulated glycocalyx to escape from host's immunity. To protect themselves from bacteriophages bacteria have a defense mechanism known as RNAi(RNA interference) which you'll know in higher classes.

Answer 2

Ummm.. Heyy -_-
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Bacteria made from @) Cell wall 
                                  @) Plasma Membrane
                                  @) Glycocalyx  
The Glycocalyx Help em' to survive em in extreme conditions like extreme hot or cold weather.