While completing this practice set, mimic the testing environment as much as possible. Check your
answers with the key on the last pages only after completing the entire set. Refer to the exam prep
videos for more info
...
While completing this practice set, mimic the testing environment as much as possible. Check your
answers with the key on the last pages only after completing the entire set. Refer to the exam prep
videos for more information on how to make the most of the practice sets.
Parathyroid hormone is manufactured and secreted by chief cells of the parathyroid gland.
Parathyroid hormone binds to the G coupled receptor parathyroid hormone 1 receptor (PTH1R)
on osteoclast cells. Osteoclast cells are generated in the bone marrow and migrate to the skeleton
to break down bone when activated to do so. The binding of parathyroid hormone to PTH1R
ultimately activates proteins within the osteoclast which facilitate its migration to the skeleton.
The osteoclasts coat the bone (composed of other cells called osteocytes) and they produce
various materials and enzymes which work both inside the osteoclast cell and outside the
osteoclast cell to break down the bone. Bone breakdown releases calcium for the body to use.
The disease osteoporosis is caused by too much bone being broken down by osteoclasts. It is
often caused by mutations in the PTH1R receptor.
1. What would be the result if, during the manufacture of parathyroid hormone there was a
mutation such that the SRP binds to the ER signal but cannot release itself from the ER
signal?
a) None of the primary structure will be completed.
b) Part of the primary structure will be completed.
c) The primary structure will be completed but not the secondary and tertiary
structures.
2. Parathyroid hormone’s 3D shape is like a coiled snake. However, it requires a second unit
of the “coiled snake” to function, making it a dimer. It’s dimerized, functional shape is
which individual level of structure?
a) Primary
b) Secondary
c) Tertiary
d) Quaternary
3. Acid phosphatase is an enzyme that works in the lysosome of osteoclasts and aids in the
breakdown of bone. Which signal sequences does acid phosphatase receive during its
manufacture?
a) ER signal
b) Chemical label
c) ER signal and chemical label
d) Peroxisome signal
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