Pathogen - A biological agent that causes disease.⏎
Protein - Large molecules composed of one or more chains of amino acids in a specific order determined by the base sequence of nucleotides in the DNA coding.⏎
Replication - The process of producing a copy of a strand of DNA.⏎
Pandemic - An increase in the occurrence of a particular disease over a very large region, such as a continent or the entire globe, that is greater than what is expected over a given period of time.⏎