Chloroplasts have no innate method of movement, but they are connected to fibers called actin which respond to light and move the chloroplasts around a cell according to the intensity of light exposure. This allows plants to take advantage of key brightness indexes while avoiding harmful overexposure.
The amount of actin in a given cell determines how far the chloroplasts in that cell can move. Limited actin threads mean less responsive chloroplasts and thus leaves that appear less vibrantly green and that process the energy from light less effectively. Strong, lengthy actin threads haul chloroplasts around the inside of the cell so that they are always in the optimal position for shelter or for absorption.
Actin growth is encouraged by certain proteins that occur naturally inside the cells of certain plants. These fibers then promote the plant's health and ensure its survival in unpredictable conditions by enabling its chloroplasts to do their jobs. Without chloroplasts, plants would be desiccated by the sunlight they feed off of.
Chloroplasts are responsible for the tendency in plants to appear bright green. This is because the chloroplasts, when the light is right, rise close to the cell surface and denude the skin of the plant with their particular spectrum of visible reflected light, which is bright green.