TLS Online TPP Program

#Question id: 34168


Angiotensin II stimulates aldosterone production in the zona glomerulosa by binding to AT1 receptors. Which of the following best describes the intracellular signaling pathway and its role in aldosterone biosynthesis?

#Unit 7. System Physiology – Animal
  1. AT1 activates cAMP via Gs protein, enhancing 11β-hydroxylase activity for cortisol synthesis
  2. AT1 activates adenylyl cyclase, increasing cAMP and PKA, which upregulates LDL receptor expression
  3. AT1 signals through Gq, activating phospholipase C, which increases PKC activity and promotes aldosterone synthase function
  4. AT1 signals via Gi protein to inhibit cAMP and reduce cortisol feedback, indirectly promoting aldosterone release
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TLS Online TPP Program

#Question id: 4484

#Unit 3. Fundamental Processes

Match General Transcription Factors with their functions;

    i. TAFs

 A. Appears to regulate the binding of TBP to DNA. It does this using an inhibitory flap that binds to the DNA-binding surface of TBP, another example of molecular mimicry. This flap must be displaced for TBP to bind TATA.

  ii. TFIIB

B. Insert into the RNA-exit channel and active center cleft of Pol II in a manner analogous to the sigma region 3/4 linker in the bacterial case.

  iii. TFIIH

 C.  As an ATP-driven translocator of double-stranded DNA.

   iv. TFIIF

D. This two-subunit (in humans) factor associates with Pol II and is recruited to the promoter together with that enzyme.

TLS Online TPP Program

#Question id: 4485

#Unit 3. Fundamental Processes

In multicellular organisms, regulatory sequences can spread thousands of nucleotides from the promoter—both upstream and downstream—and can be made up of tens of regulator binding sites. Often, these binding sites are grouped in units called_?

TLS Online TPP Program

#Question id: 4486

#Unit 3. Fundamental Processes

Activators can recruit factors needed for polymerase to initiate or elongate transcription. In all of these functions, the activator is merely recruiting proteins to the promoter. In bacteria, RNA polymerase is the only protein that needs to be recruited; this is not the case in eukaryotes. Indeed, in eukaryotes, a given activator might work in all three ways:

 1.    Recruitment of nucleosome modifiers and remodelers

i.     “open” the promoter

 2.    Recruitment of general transcription factors and mediators

ii.      That stimulate Pol II initiation and elongation

 3.       Recruitment of protein complexes

iii.     To recruit PTEFb/SEC

TLS Online TPP Program

#Question id: 4487

#Unit 3. Fundamental Processes

Choose correct statements about nucleosome modifiers

TLS Online TPP Program

#Question id: 4488

#Unit 3. Fundamental Processes

One component of thecomplex bears bromodomains and thus binds to acetylated nucleosomes better than to unacetylated nucleosomes. Thus, a gene bearing acetylated nucleosomes at its promoter will likely have a higher affinity for the transcriptional machinery than one with unacetylated nucleosomes.

TLS Online TPP Program

#Question id: 4489

#Unit 3. Fundamental Processes

HSP70 gene from Drosophila. This gene, activated by heat shock, is controlled by two activators GAGA binding factor and HSF,In response to heat shock, HSF binds to specific sites at the promoter and recruits a kinase, P-TEFb (positive transcription elongation factor). What is the proper mechanism of pausing and release of Pol II ?