A female patient has unexplained severe hypernatremia (plasma Na+ = 167 mmol/L) and complains of frequent urination and large urine volumes. A urine specimen reveals that the Na+ concentration is 15mmol/L (very low) and the osmolarity is 155 mOsm/L (very low). Laboratory tests reveal: plasma renin activity = 3 ng angiotensin I/ml/hr (normal = 1.0), plasma antidiuretic hormone (ADH) = 30 pg/ml (normal = 3 pg/ml), and plasma aldosterone = 20 ng/dL (normal = 6 ng/dL). Which of the following is the most likely reason for her hypernatremia?

#Question id: 4401

#Unit 3. Fundamental Processes

Which of the following occur(s) during Pol II transcription preinitiation complex formation?

a. TFIIA binds to TFIIB.  b. TFIIB unwinds the DNA.

c. TFIIB contacts both TATA box–binding factor and DNA.

d. DNA bends.

#Question id: 4402

#Unit 3. Fundamental Processes

Chromatin-mediated repression of transcription involves

a. modification of lysine residues in histones. 

b. large, multiprotein complexes.

c. acetylation of histone tails.   

d. deacetylation of histone tails.

#Question id: 4403

#Unit 3. Fundamental Processes

 Which of the following does (do) not require a DNA helicase activity?

a. SWI/SNF function  b. Pol II open-complex formation

c. transcription-factor binding to DNA

d. deacetylation of histone tails

#Question id: 4404

#Unit 3. Fundamental Processes

The yeast two-hybrid system can be used to identify

a. proteins that interact with a known or “bait” protein.

b. proteins that interact with a “fish” domain.

c. cDNAs that encode interacting proteins.

d. co-activators and co-repressors.

#Question id: 4405

#Unit 3. Fundamental Processes

Which of the following can occur when steroid hormone binds to its cognate receptor?

a. conformational changes in the receptor

b. translocation of the receptor out of the cell membrane

c. binding of the receptor to DNA response elements

d. stimulation of transcription

#Question id: 4406

#Unit 3. Fundamental Processes

An electrophoretic mobility shift assay (EMSA) was conducted to check for the binding of TFIIB to a segment of a DNA promoter region. Which of the following approaches could be used to confirm that TFIIB is indeed binding?