Trisomy 18 is one of the most common trisomies observed in human populations. You prepare DNA samples from two unrelated infants, both with trisomy 18, and from their parents. You then type the infants and their parents for four SSRs distributed along chromosome 18:

 

                                              

In which parent did nondisjunction occur in Family 2?

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#Question id: 34138

#Unit 7. System Physiology – Animal

Which of the following hormones are nanopeptides with a disulfide ring at one end?

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#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.

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#Question id: 34140

#Unit 7. System Physiology – Animal

Following stimulus stimulates vasopressin-secreting neurons, EXCEPT?

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#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.

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#Question id: 34142

#Unit 7. System Physiology – Animal

Somatostatin inhibits the secretion of following hormones, EXCEPT?

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#Question id: 34143

#Unit 7. System Physiology – Animal

Which of the following best explains how normal plasma oxytocin levels at the onset of labor can still result in powerful uterine contractions?