1. The sequence for smooth muscle contraction is... A. increased cystolic calciu
ID: 3476999 • Letter: 1
Question
1. The sequence for smooth muscle contraction is...
A. increased cystolic calcium, which binds to calmodulin in cytosol, which binds with myosin cross bridges, resulting in contraction.
B. increased cystolic calcium, which binds to calmodulin in cytosol, complex binds with myosin light-chain kinase, which uses ATP to phosphorylate myosin cross bridges, which bind to actin filaments, resulting in contraction.
C. increased cystolic calcium, which binds to troponin, which moves tropomyosin from blocking active sites on actin filament, which binds with myosin cross bridges, resulting in contraction.
D. increased cystolic calcium, which binds to which binds to calmodulin in cytosol, which moves tropomyosin from blocking active sites on actin filament, which binds with myosin cross bridges, resulting in contraction.
E. increased cystolic calcium, which binds to troponin, complex binds with myosin light-chain kinase, which uses ATP to phosphorylate myosin cross bridges, which bind to actin filaments, resulting in contraction.
2. The sequence for skeletal muscle contraction is...
A. increased cystolic calcium, which binds to troponin, complex binds with myosin light-chain kinase, which uses ATP to phosphorylate myosin cross bridges, which bind to actin filaments, resulting in contraction.
B. increased cystolic calcium, which binds to calmodulin in cytosol, which binds with myosin cross bridges, resulting in contraction.
C. increased cystolic calcium, which binds to troponin, which moves tropomyosin from blocking active sites on actin filament, which binds with myosin cross bridges, resulting in contraction.
D. increased cystolic calcium, which binds to calmodulin in cytosol, complex binds with myosin light-chain kinase, which uses ATP to phosphorylate myosin cross bridges, which bind to actin filaments, resulting in contraction.
E. increased cystolic calcium, which binds to which binds to calmodulin in cytosol, which moves tropomyosin from blocking active sites on actin filament, which binds with myosin cross bridges, resulting in contraction.
3. Which of the following statements is true concerning calcium ions?
A. in smooth muscle it binds with troponin.
B. in skeletal muscle it binds with calmodulin
C. in skeletal uscle it binds with tropomyosin.
D. in smooth muscle it binds with calmodulin.
E. in smooth muscle it binds with myosin light- chain kinase.
Explanation / Answer
1.
The sequence for smooth muscle contraction is...
B. increased cytosolic calcium, which binds to calmodulin in cytosol, complex binds with myosin light-chain kinase, which uses ATP to phosphorylate myosin cross bridges, which bind to actin filaments, resulting in contraction.
2.
The sequence for skeletal muscle contraction is...
C. increased cytosolic calcium, which binds to troponin, which moves tropomyosin from blocking active sites on actin filament, which binds with myosin cross bridges, resulting in contraction.
3. The answer is: D. in smooth muscle it binds with calmodulin.
In smooth muscle, calcium ions bind with calmodulin, and this complex then bind with myosin light-chain kinase
In skeletal muscle, calcium ions bind to troponin molecule which moves tropomyosin from blocking active site on actin, such that myosin head can now bind to actin.
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