Final answer:
Bacterial movement is facilitated by a structure called the flagellum, which allows bacteria to propel themselves forward in response to environmental signals like chemical gradients in a process called chemotaxis.
Step-by-step explanation:
For bacteria, the cellular structure that aids in movement and can even propel the organism toward food particles or bacteria is the flagellum. Flagella are tail-like structures that rotate to move the bacteria forward. Eukaryotic cells may also have flagella, but it is a rare occurrence, and the structure and makeup differ from prokaryotic flagella. Bacteria can have different flagellar arrangements such as amphitrichous, lophotrichous, or peritrichous, which influence their directional movement. The most common environmental signal that bacteria move in response to is a chemical gradient, a process known as chemotaxis. During chemotaxis, bacteria increase the length of their runs (forward movement) and decrease the length of their tumbles (reorientation movement) to move toward an attractant, such as a food source.