The sequence of bases in DNA are like the letters of a coded message. What would happen if those letters changed accidently, altering the message? Would the cell still understand its meaning? For example, let’s say you needed to call someone about a job and the phone number was 678-3245, but you were given a message to call 768-3254. Since you did not receive the correct message you wouldn't not be able to reach the person you intended.
Now and then cells make mistakes in copying their own DNA. They may insert the wrong base or even skip a base as a strand is put together. These variations are called mutations.
Many mutations are produced by errors in genetic processes like DNA replication. Some mutations arise from mutagens—chemicals or physical agents in the environment that cause a mutation.
Directions: Watch the video Gene Mutations to learn more about mutations and what causes them.