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BIOL 1412 Lecture Notes - Lecture 15: Sliding Filament Theory, Myosin Head, Myosin

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School
University of Manitoba
Department
Biological Sciences
Course
BIOL 1412
Professor
Messing

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Document Summary

Adp+pi still on myosin head and energy stored in myosin head activated therefore ready to bind as soon as binding sites are exposed: excitation of the muscle fibre electrical event, sarcolemma is depolarized. If ca2+ in cytosol remains high, it keeps binding to the troponin : activated myosin heads bind to actin, filament, atp attaches to myosin, releases from actin, activates head. This cycle keeps repeating many times to shorten a muscle. The myosin heads are not synchronized, as to keep the shape. In sliding filament mechanism: sacrolemma shorten appendix fig 2 ch 9. A band remains the same length: myofibrils shorten therefore the muscle shortens. Relaxation fig 9. 8: ach broken down by acetylcholinesterase ( ache) on motor end plate. Krebs cycle recycled: sr actively takes up ca2+ Ca2+ - atpase: atp binds to myosin heads released from actin, tropomyosin moves back to cover myosin binding sites on actin.

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Related Questions

Describe the process of skeletal muscle contraction by assembling the following 10 events in the proper order. Your answer must be written in complete sentences- do not just list the letters or the events- write it out. Begin your description with an action potential traveling down a motor neuron and end with the muscle in it's relaxed state.

A) T and T system undergoes a conformational change, exposing the myosin binding sites on actin

B) myosin heads/cross bridges bind to actin and flex, shortening the sacromere

C) the motor neuron triggers an action potential at the neuromuscular junction

D) calcium ions bind to the T and T system

E) actin filaments are pulled toward the center of the sacromere, shortening the muscle fiber

F) muscle fiber is stimulated at the neuromuscular junction

G) myosin head/cross-bridges bind to actin

H) APs travel down the T-tubules to the sarcoplasmic reticulum

I) in response to an AP, calcium ions are released into the cytosol/space around the myofibrils

J) calcium ions actively transported into the sarcoplasmic reticulum

K) myosin head continues to attach, flex, release, extend, and reattach as long as calcium ions are present