FQ 21-30

    Cards (16)

    • What do the dark bands in skeletal muscle contain?
      Myosin filaments and overlapping actin ends
    • Why are dark bands called I bands?
      They are anisotropic to polarized light
    • How many myofibrils does each muscle fiber contain?
      Several hundred to several thousand
    • How many actin and myosin filaments are in each myofibril?
      About 1500 actin and 3000 myosin filaments
    • What do the light bands in skeletal muscle contain?
      Only actin filaments
    • Why are light bands called I bands?
      They are anisotropic to polarized light
    • What is the diameter range of skeletal muscle fibers?
      10 to 80 micrometers
    • What does the Z disc do in skeletal muscle?
      Attaches myofibrils across the muscle fiber
    • What is the molecular weight of the titin molecule?
      About 3 kDa
    • What role does titin play in skeletal muscle?
      Sustains myosin and actin filaments in place
    • What is the length of the sarcomere when contracted?
      About 2 micrometers
    • What happens to actin filaments during muscle contraction?
      They completely overlap the myosin filaments
    • What is present in the sarcoplasm of muscle fibers?
      Tremendous numbers of mitochondria
    • What is the function of mitochondria in muscle fibers?
      Supply energy in the form of ATP
    • How do mitochondria align in muscle fibers?
      They lie parallel to the myofibrils
    • What energy form do mitochondria supply to contracting myofibrils?
      Adenosine diphosphate (ADP)
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