The Structure of Vasopressin Is Very Similar to That of Oxytocin

question 18

Multiple Choice

The structure of vasopressin is very similar to that of oxytocin (primary sequence of vasopressin: cysteine - tyrosine - phenylalanine - glutamine - asparagine - cysteine - proline - arginine - glycine) , which is also a nonapeptide with a disulfide bridge. One of the most important roles of vasopressin is to regulate the body's retention of water; it is released when the body is dehydrated and causes the kidneys to conserve water, thus concentrating the urine, and reducing urine volume. In addition, it has a variety of neurological effects on the brain. What are the differences in the structures of vasopressin and oxytocin?
I. residue #3: isoleucine (oxytocin) vs. phenylalanine (vasopressin)
II. residue #7: isoleucine (oxytocin) vs. phenylalanine (vasopressin)
III. residue #8: leucine (oxytocin) vs. arginine (vasopressin)
IV. residue #4: asparagine (oxytocin) vs. cysteine (vasopressin)

• A) I and II are correct
• B) II and III are correct
• C) I and III are correct
• D) II and IV are correct

---

Definitions:

Receptor Cells

Specialized cells that respond to specific types of energy (e.g., light, sound) and convert it into neural activity.

Taste Buds

Sensory organs located on the tongue and are responsible for the perception of taste.

Psychophysical Study

The branch of psychology that deals with the relationships between physical stimuli and their subjective perception or psychological effects.

Absolute Threshold

The minimum stimulus intensity that an organism can detect at least 50% of the time, a concept used in sensory psychology.