Using the Definite Article the before Nouns
In a paragraph, once a noun is identified
(that is, it is clear to the reader), then the next time that
the noun is used, you can use the definite article the
to refer to that noun. Take a look at the following examples:
Examples with countable
We cloned a cow. The cow is
genetically identical to its parent.
The high throughput assay generated some hits.
The hits were further analyzed by Johnson.
Examples with non-countable
We discovered some protein in the flask.
The protein was then isolated.
The next step in the assay was purification.
The purification required several hours to complete.