An Environmental Activist is a broad term for someone who is actively engaged in fighting for the environment. It could even be said that both environmental lawyers and environmental journalists are environmental activists in their own rights. However, someone could still be an activist without being a journalist or a lawyer, and this activist may be involved in fundraising, petitioning, and actively protesting. Environmental journalism is quite self explanatory; to report though written and/or verbal media to spread information on issues pertaining to the environment. An environmental lawyer fights legal battles to ensure dangerous actions are prevented or held accountable, and may also impact future legislation regarding environmental management.
It will all make more sense if you start from the beginning of the sequence with the structure of DNA. You will remember that messenger RNA contains a sequence of bases which, read three at a time, code for the amino acids used to make protein chains. Each of the sets of three bases is known as a codon.
