Muscle Contraction - Actin and Myosin

This video shows that muscle contraction is dependent on ATP (the energy carrier in cells). The preparation of muscle is made from rabbit muscle. Most of the cellular content is removed and all that is left is the contractile machinery -- actin and myosin. The glycerinated muscle preparation is available from Carolina Biological Supply Company (item #203525 ATP Muscle Set; or # 203520 Glycerinated Skeletal Muscle; www.carolina.com).

Category:

Education

Tags:

• muscle
• cell
• biology
• actin
• myosin

[Svonavje]

the rabbit was probably dead anyhow. lol geez :D

[VPolecat]

actuallly ATP causes relaxation and not contraction of muscle fibers...ATP binds the myosin head so this later unbinds from the actin sites exposed by the tropomyosin uncovering caused by the calcium binding to troponin...of course much before and after this happens, ATP is always necessary for any action in the cells, including calcium release and uptake from the SR

[VPolecat]

@VPolecat I see there are some people confused, so I'll try to clear it up a little bit.

The dephosphorylation of ATP into ADP+P causes contraction. The binding of ATP to myosin causes relaxation.

I hope this way there is less confusion to some heads.

[WalkItOutClock]

@VPolecat What? You are just blatantly incorrect...

[shocktrauma13]

@VPolecat pretty good 

[busybuzzbuzz]

And how does this relate to redox+

[puppetmaster5889]

how did the ATP alone cause the muscle to contract? What about the whole process about sodium and potassium? and the calcium allowing the myosin head to bind with actin and perform the power stroke?

What about all of that?

[bebeecakes]

that's so cool! good job!

[BEANMANOR]

Yes, pretty much anything with an -in or an -ase ending is protein. More specifically, the -ase ending indicates that it is an enzyme.

[BEANMANOR]

Well, actually... While ATP does bind and cause the myosin head to detach from the actin filament, this is the start of a new contraction! ATP is cleaved and the chemical energy that is stored in ATP is converted into the mechanical energy that cocks the mysosin head. (It is now like a compressed spring.) Should Ca+2 come along and bind troponin and pull tropomyosin aside, the head binds and its stored energy is released in the form of a power stoke causing a contraction of the sarcomere.