KINESIOL 1A03 Lecture Notes - Lecture 10: Voltage-Dependent Calcium Channel, Chemical Synapse, Resting Potential

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29 Oct 2018

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Sarcomere organization: always an overlap (at rest) of myosin and actin allows for extension beyond normal length, and this allows for contractions to still occur (as long as there is still overlap) I-band: (cid:862)light bands(cid:863) the area where there is only actin myofilaments (z disc is in the middle). Contains the m line and only myosin tails: zone of overlap: the rest of the h zone where the actin and myosin are overlapping. Physiology of skeletal muscle: sliding filament theory, relaxed muscle, partially contracted muscle: Sarcomere shortens as z disks move towards eachother (h zone and i band narrows, a band does not narrow: maximally contracted muscle: Muscle action potential propagated along sarcolemma and into t-tubules. Ca+ channels in the sr open and calcium is released into the sarcoplasm. Ca+ binds to troponin movement of tropomyosin off of myosin binding site. Heads of myosin can bind active sites on actin cross bridge forms.

Related Questions

1)Describe the directions in which the two motor proteins, kinesin and dynein, travel along a microtubule. Which of the two proteins moves materials towards the Golgi and which moves materials away from the Golgi? Lastly, what is the speed of kinesin dependent on?

2)What are microfilaments crucial for? How do they self-assemble? Which end do they prefer to elongate from?

3)Describe what types of filaments are in each of the bands of the sarcomere. As a muscle fiber is shortened, describe what happens to each of the bands in the sarcomere as the Z lines move inwards.

4)Describe the role of calcium ions in muscle contraction.

5)List the various types of actin-binding proteins

6) A. What are 3 functions of the cytoskeleton?

B.What are the three filaments that compose the cytoskeleton, and what are they composed?

7)How do they see the internal structures of cells in the microscope? What do proteins get labeled with?

8)Myosin II action (Figure 9.61) differs from that of kinesin (Figure 9.15) in that one of the kinesin heads is always in contact with a microtubule, whereas both myosin heads become completely detached from the actin filament. How are these differences correlated with the two types of motor activities in which these proteins engage?

9)If a myofibril were pulled so that the sarcomeres increased in length by approximately 50 percent, what effect would you expect this to have on the contractile ability of the myofibril? Why? What effects would this have on the H, A, and I bands?

10)Because cytoplasmic vesicles are seen to move in both directions within an axon, can you conclude that some microtubules are oriented with their plus end facing the axon terminus and others oriented with the opposite polarity? Why or why not?

KINESIOL 1A03 Lecture Notes - Lecture 10: Voltage-Dependent Calcium Channel, Chemical Synapse, Resting Potential

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