|a calculus or concretion found in the stomach or intestines of certain animals, esp. ruminants, formerly reputed to be an effective remedy for poison.|
|a screen or mat covered with a dark material for shielding a camera lens from excess light or glare.|
cistron cis·tron (sĭs'trŏn')
The smallest functional unit of heredity; a length of chromosomal DNA associated with a single biochemical function and essentially equivalent to a gene.
|cistron (sĭs'trŏn') Pronunciation Key
A section of DNA that contains the genetic code for a single polypeptide and functions as a hereditary unit.