Chemotaxis is
A the ability to move using a flagellum
B the ability to move nutrients across the cell membrane
C the ability to move toward or away from a chemical signal
D the ability to exclude chemicals from the cell
The correct answer and explanation is:
The correct answer is C: the ability to move toward or away from a chemical signal.
Chemotaxis is a biological phenomenon where an organism or cell moves in response to a chemical stimulus. This can involve moving toward a substance, which is called positive chemotaxis, or moving away from it, known as negative chemotaxis. This process is vital for many organisms, from bacteria to human immune cells, as it helps them locate food, navigate toward signaling molecules, or avoid harmful substances.
In bacteria, for instance, chemotaxis is facilitated by flagella, which are tail-like structures that rotate and propel the bacterium toward or away from specific chemicals. This movement is guided by receptors on the cell surface that detect concentrations of particular chemicals. When the concentration of a favorable chemical (like a nutrient) increases, the bacterium will move toward it. Conversely, if a harmful substance is detected, the bacterium will move away.
In humans, chemotaxis plays a crucial role in immune responses. White blood cells, like neutrophils, exhibit chemotaxis to locate and fight infections. They are attracted to areas where there are signals from pathogens, such as cytokines or other chemical cues. These cells will then move toward the infection site to neutralize foreign invaders.
Chemotaxis is essential for the survival and functionality of many organisms. It allows cells to adapt to their environments, find resources, and respond to external threats. This process is regulated by complex signaling pathways that include receptors, secondary messengers, and motor proteins like flagella or pseudopodia.