Final answer:
When CheY becomes phosphorylated, it promotes tumbling in a bacterium.
Step-by-step explanation:
When CheY becomes phosphorylated, it promotes tumbling in a bacterium. CheY is a protein that plays a role in bacterial movement. Phosphorylation occurs when a phosphate group is added to a molecule, in this case, CheY. Phosphorylated CheY then interacts with the flagellar motor and causes a change in direction, resulting in tumbling. When CheY becomes phosphorylated, it induces tumbling behavior in bacteria, which is a rapid and sudden change in the direction of swimming. Phosphorylated CheY interacts with the flagellar motor, causing the flagella to change the rotational direction from counterclockwise (smooth swimming) to clockwise, leading to a tumbling motion. This tumbling allows the bacterium to reorient and eventually swim in a new direction, which is a crucial part of chemotaxis – the movement of an organism in response to a chemical stimulus.