You Are Interested in Examining the Psf Gene $\quad$ $\quad$

question 67

Multiple Choice

You are interested in examining the Psf gene.It is known that Psf is normally produced when cells are exposed to high levels of both calcium (Ca²⁺) and magnesium (Mg²⁺) .MetA, MetB, and MetC are important for binding to the promoter of the Psf gene and are involved in regulating its transcription.MetA binds to the "A" site in the promoter region, MetB to the "B" site, and MetC to the "C" site.You create binding-site mutations in the A, B, and C sites and observe what happens to transcription of the Psf gene.Your results are summarized in Table 8-12. $\quad$$\quad$$\quad$$\quad$$\quad$$\quad$$\quad$$\quad$$\quad$$\quad$$\quad$$\underline{\text { Transcription in the presence of } \mathrm{Ca}^{2+} \text { and/or } \mathrm{Mg}^{2+}}$
$\begin{array}{lcccc}\text { Binding sites present } & \begin{array}{l}\text { No } \mathrm{Ca}^{2+} \\\text { or } \mathrm{Mg}^{2+}\end{array} & \begin{array}{l}\text { With } \\\mathrm{Ca}^{2+}\end{array} & \begin{array}{l}\text { With } \\\mathrm{Mg}^{2+}\end{array} & \begin{array}{l}\text { With } \mathrm{Ca}^{2+} \\\text { and } \mathrm{Mg}^{2 *}\end{array} \\\hline \text { A, B, and C } & - & - & - & ++ \\\hline \text { none } & - & - & - & - \\\hline \text { A only } & - & - & + & + \\\hline \text { B only } & - & - & - & - \\\hline \text { C only } & - & + & - & + \\\hline \text { A and B only } & - & - & - & + \\\hline \text { A and C only } & - & + & + & ++ \\\hline \text { B and C only } & - & - & - & +\end{array}$

$\text {For this table: -= no transcription of Pst,}$
$\text {\( += \) low level of transcription of Psf, and}$
$\text {\( ++= \) high levels of transcription of Pst.}$
Table 8-12
Which of the following proteins are likely to act as gene repressors?

• A)MetA only
• B)MetB only
• C)MetC only
• D)both MetA and MetC

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Definitions:

Efferent Neurons

Nerve cells that carry neural impulses away from the central nervous system toward muscles to cause movement, also known as motor neurons.

Afferent Neurons

Nerve cells that carry sensory information from the body's tissues and organs to the brain or spinal cord.

Spinal Cord

The central nerve column that runs down the back and transmits messages between the brain and the rest of the body.

Gate-control Theory

A theory that suggests pain is not merely a direct result of activation of pain receptor nerves but is also subject to modulation by psychological factors at the spinal cord level.