The role of ABA signaling during water stress in the guard cells in presence and absence of ABA;

a) Anion effl¬ux leads to depolarization of the plasma membrane, which drives K+ effl¬ux. The eff¬lux of ions (A– and K+) reduces the turgor pressure of guard cells, resulting in stomatal closure.

b) Both OST1 and CPKs phosphorylate and thereby activate plasma membrane anion channels, leading to ef¬flux of anions (A–). But  this process can be inhibited directly by PP2Cs 

c) Inhibition of PP2C activity releases the positive regulator kinase OST1 from inhibition, resulting in both phosphorylation and activation of NADPH oxidases (RBOHs)

d) RBOHs catalyze the formation of apoplastic reactive oxygen species (ROS),  which triggers opening of plasma membrane Ca2+-permeable ion channels 

e) The resulting elevation of cytosolic Ca2+ leads to activation of calcium-dependent protein kinases (CPKs), which can also activates the RBOH proteins further promoting Ca2+ infl¬ux into the cytosol.

Which statements belongs to the presence and absence of ABA during signalling;

I. In presence of  ABA

II. In absence of ABA

Which of the following combination from the given above statements is correct?

#Question id: 4513

#Unit 3. Fundamental Processes

Different snRNPs recognize the same (or overlapping) sequences in the pre-mRNA at different stages of the splicing reaction, which two snRNPs recognizing the 5’ splice site

#Question id: 4514

#Unit 3. Fundamental Processes

What is true about coactivators,

A. The coactivators act directly by binding to the DNA

B. The coactivators act indirectly—not by binding to the DNA

C. Are required for essential communication between the activators and the complex composed of Pol II.

D. Are required for essential communication between the and the basal (or general) transcription factors.

#Question id: 4515

#Unit 3. Fundamental Processes

Transcription Activators are,

A. Known to facilitate transcription at hundreds of promoters,

B. Specific for a few promoters,

C. Sensitive to the binding of signal molecules,

D. Providing the capacity to activate or deactivate transcription in response to a changing cellular environment.

#Question id: 4516

#Unit 3. Fundamental Processes

High mobility group (HMG) proteins

A. are a common type of architectural regulator

B. facilitating the looping of the DNA

C. the binding is relatively very specific

D. are abundant in chromatin and bind to DNA with limited specificity.

#Question id: 4517

#Unit 3. Fundamental Processes

Statement: When phosphorylated, CREB binds to CREs near certain genes and acts as a transcription factor, turning on the expression of these genes.

Explanation: I-Regulation can result from phosphorylation of Nuclear transcription factor

II- Activation of a protein kinase in the nucleus that phosphorylates specific DNA-binding proteins and thereby alters their ability to act as transcription factors.

#Question id: 4518

#Unit 3. Fundamental Processes

The sequence of transcriptional activation events at a typical Pol II promote

I- Mediator facilitates the binding of TBP (or TFIID) and TFIIB, and the other basal transcription factors and Pol II then bind.

II- Activators bind the DNA.

III-The activators recruit the histone modification/nucleosome remodeling complexes and a coactivator such as Media.

IV- Phosphorylation of the carboxyl-terminal domain (CTD) of Pol II leads to transcription initiation.