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TLS Online TPP Program

#Question id: 3981

The diagram below represents a hypothetical operon in the bacterium E. coli.  The operon consists of two structural genes (A and B), which code for the enzymes A-ase and B-ase, respectively, and also includes P (promoter) and O (operator) regions as shown.

 When a certain compound (X) is added to the growth medium of E. coli, the separate enzymes A-ase and B-ase are both synthesized at a 50-fold higher rate than in the absence of X.  (X has a molecular weight of about 200.)  Which of the following statements is true of the operon decribed above?

#Unit 3. Fundamental Processes

  1. All four genes (A, B, O, and P) will be transcribed into an mRNA that will then be translated into four different proteins.

  2. The 3' end of the mRNA from the operon will correspond to the left end of the operon as drawn.

  3. The 5' end of the messenger from this operon will correspond to the right end of the operon as drawn.

  4. When RNA polymerase makes mRNA from this operon, it begins RNA synthesis just to the left of gene A.

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TLS Online TPP Program

#Question id: 34137

#Unit 7. System Physiology – Animal

Which of the following best explains why glucose uptake into liver cells continues in insulin-resistant states, even when skeletal muscle glucose uptake is impaired?
TLS Online TPP Program

#Question id: 34138

#Unit 7. System Physiology – Animal

Which of the following hormones are nanopeptides with a disulfide ring at one end?
TLS Online TPP Program

#Question id: 34139

#Unit 7. System Physiology – Animal

I. Oxytocin and vasopressin are typical neural hormones , that is, hormones secreted into the circulation by nerve cells.
II. Vasopressin and oxytocin each have a characteristic neurophysin associated with them in the granules in the neurons.
III. The precursor for AVP, prepropressophysin , contains a 19-amino-acid residue leader sequence followed by AVP, neurophysin II, and a glycopeptide. 
IV. Prepro-oxyphysin, the precursor for oxytocin, is a similar but smaller molecule that lacks the glycopeptide.
TLS Online TPP Program

#Question id: 34140

#Unit 7. System Physiology – Animal

Following stimulus stimulates vasopressin-secreting neurons, EXCEPT?
TLS Online TPP Program

#Question id: 34141

#Unit 7. System Physiology – Animal

I. Oxytocin causes contraction of the smooth muscle of the uterus.
II. The suckling of an infant at the breast stimulates the touch receptors, the nuclei are stimulated, oxytocin is released.
III. The sensitivity of the uterine musculature to oxytocin is enhanced by estrogen.
IV. Progesterone directly stimulates myometrial contraction while simultaneously reducing oxytocin clearance.
TLS Online TPP Program

#Question id: 34142

#Unit 7. System Physiology – Animal

Somatostatin inhibits the secretion of following hormones, EXCEPT?