Question

You have created a new transgenic mouse in which the troponin complex is now independent of calcium regulation.

-- What would happen in the skeletal muscles of these mice if troponin was:
A) never activated
B) always activated

Answer 1

If troponin in transgenic mice's skeletal muscles is never activated, the muscles cannot contract, leading to paralysis or muscle weakness. If troponin is always activated, muscles would be in a constant state of contraction, potentially causing cramps.

Step-by-step explanation:

In the skeletal muscles of mice, the troponin complex plays a crucial role in muscle contraction by being sensitive to calcium (Ca2+) ions. When Ca2+ ions bind to troponin, it induces a conformational change that moves tropomyosin away from the myosin-binding sites on actin filaments, allowing muscle contraction to occur.

If troponin is never activated (meaning it does not respond to calcium ions), the tropomyosin would remain in place, continuously blocking the myosin-binding sites on actin, preventing muscle contraction and resulting in paralysis or severe muscle weakness. In contrast, if troponin is always activated (as if it is permanently bound to calcium), tropomyosin would be permanently moved aside, leaving the myosin-binding sites on actin exposed. This would lead to a continuous state of muscle contraction or cramps because the muscles would not be able to relax.