One patient at your audiology clinic has an actin defect, and another patient has a microtubule defect. How might these defects affect the function of their hair cells in hearing?

Question

Hair cells are delicate sensors of sound, movement, and gravity. They are stimulated by movement of the stereocilia -- which are actually microvilli -- and the single kinocilium, which is a true cilium.


A.  Neither actin nor microtubule mutations will disrupt hair cell cilia function.
B.  Only the actin mutation will affect hair cell cilia function.
C.  Only the microtubule mutation will affect hair cell cilia function.
D.  Both can create problems in hair cell cilia function.

Clarify Question
What is the key concept addressed by the question?
What type of thinking is required?

Gather Content
What do you already know about hair cells? What other information is related to the question?

Choose Answer
Given what you now know, what information is most likely to produce the correct answer?

Reflect on Process
Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?

Answer 1

D.  Both can create problems in hair cell cilia function.

Clarify Question
What is the key concept addressed by the question?
        · Would actin or microtubule defects affect hair cells?
What type of thinking is required?
            o This is an analyze question because you have to break down the components of a sensory hair cell and what proteins are involved in order to determine how defects in these proteins would effect hearing.

Gather Content
What do you already know about hair cells? What other information is related to the question?
        · You already know that hair cells are found in the organ of Corti in the inner ear. These hair cells have one long kinocilium that is a true cilium that contains microtubules and many smaller stereocilia which are microvilli containing actin fibers. If there is a defect in either microtubules or actin, this may hinder hair cell and thus hearing function.

Choose Answer
Given what you now know, what information is most likely to produce the correct answer?
        · As hair cells contain both microtubules (in kinocilia) and actin (in stereocilia), and since both are important in the development and function of hair cells, then a defect in either or both of these types of proteins would likely create problems for hair cell function.

Reflect on Process
Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?
        o Answering this question correctly depended upon your knowledge of the localization of actin and microtubules in sensory hair cells and understanding the function of the stereocilia and kinocilium. If you answered incorrectly, which answer did you choose? Did you think that since there is only one kinocilium per hair cell that the hair cell might still function properly without it?