DNA crossword puzzle

123456
Across
  1. 4. the central and most important part of an object
  2. 5. properties or features of an organism
  3. 6. a self-replicating material
Down
  1. 1. changing of the structure of a gene
  2. 2. a class of nitrogenous organic compounds
  3. 3. any of the class of soluble,sweet-tasting carbohydrates