Question

• Slides 31-37: Know how tropomyosin and the troponin complex are bound to actin when muscle fibers are at rest and when they are contracted; know where calcium ions are bound as part of muscle fiber contraction; also know the organelle in the muscle fiber where the calcium is released when muscle contraction is initiated

• Know the difference between oxidative and glycolytic muscle fibers

• Know the difference between slow twitch and fast twitch skeletal muscles

• Know the other two types of vertebrate muscles, where they are located, and how they contract

Answer 1

When calcium binds to troponin, the troponin changes shape, removing tropomyosin from the binding sites. The sarcoplasmic reticulum stores calcium ions, which it releases when a muscle cell is stimulated; the calcium ions then enable the cross-bridge muscle contraction cycle.

Slow oxidative (SO) fibers contract relatively slowly and use aerobic respiration (oxygen and glucose) to produce ATP. ... Glycolytic fibers primarily create ATP through anaerobic glycolysis, which produces less ATP per cycle. As a result, glycolytic fibers fatigue at a quicker rate.

The two types of skeletal muscle fibers are slow-twitch (type I) and fast-twitch (type II). Slow-twitch muscle fibers support long distance endurance activities like marathon running, while fast-twitch muscle fibers support quick, powerful movements such as sprinting or weightlifting