Answer:
Design
Explanation:
The noun <em>makeup </em>refers to the composition, constitution or arrangement of something. Similarly, <em>design </em>is also related to the configuration, layout, pattern and construction of something.
In the sentence given, <em>makeup </em>involves the structure, assembly and formation of the different components of bacteria, whose understanding of combination and function may help scientists further investigate which bacteria is beneficial for human bodies.