APPENDIX A 
30. HEPA FILTER: (High Efficiency Particulate Air Filter) A 
disposable, extended-medium, dry-t}^e filter with a particle 
removal efficiency of no loss than 99. 97% for 0. Sum particles. 
31. HOST: An organism that harbors and provides nourishment for a 
parasite. In recombinant DNA research, a cell into which foreign 
DNA has been incorporated. 
32. INFECTIOUS: Capable of invading a susceptible host, replicating, 
and causing an altered host reaction commonly referred to as a 
disease. 
33. LAMINAR AIR FLOW: Air flow in which the entire body of air 
within a designated space moves with uniform velocity in one 
direction along parallel flow lines. 
34. LABORATORY -ACQUIRED INFECTION: Any infection resulting 
from exposure to biohazardous materials in a laboratory environ- 
ment. Exposure may be the result of a specific accident or 
inadequate biohazard control procedure or equipment. 
35. MESSENGER RIBONUCLEIC ACID (mRNA): A complex molecule 
that transmits the information from the gene to a template on which 
a protein is formed. 
36. MITOCHONDRION: A DNA -containing structure present in all 
aerobic eukaryotic cells. The mitochrondria produce energy for 
the cell and divide by fission after cell division has occurred. 
37. MUTATION: Any heritable alteration of the genes or chromosomes 
of an organism. 
38. NUCLEOTIDE: A basic unit of the polymeric structure of DNA. 
Each unit contains a sugar (deoxyribose), phosphoric acid, and 
one of the following organic substances: adenine, guanine, thjmiine, 
or cytosine. 
39. ONCOGENESIS: The process of tumor formation. 
40. ORGANELLE: An independent structural body existing within cells, 
generally related to a particular cellular function, and containing 
a special group of genes within an extrachromosomal DNA molecule 
(e.g., mitochrondria and chloroplasts). 
41. PATHOGENIC: Producing or capable of producing disease. 
42. PHENOTYPE: The visible traits of an organism as determined 
by the genome or genotype. 
43. PHYLOGENETIC: Pertaining to the evolutionary development of 
any species of plant or animal. 
Appendix A — 4 
