GENERAL BIO DOUBTS

Just use this space here for general doubts about the subject.

MUSCLES ANIMATIONS !!

Pay attention to each of the animations, listen and read them carefully.
Work with the questions close to some of them.

http://www.blackwellpublishing.com/matthews/myosin.html

http://www.brookscole.com/chemistry_d/templates/student_resources/shared_resources/animations/muscles/muscles.html

http://bio-alive.com/animations/anatomy.htm

http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter10/animation__sarcomere_contraction.html

http://www.lrc.centennialcollege.ca/tutorserv/Physiology-SlidingFilamentTheory.htm

MUSCLES AND ATP

1)

• Muscle contracts:

– Occurs because of sliding of thin filaments over and between thick filaments towards center.

- Shortening the distance from Z disc to Z disc.

• A bands:

– Contain actin.

– Move closer together but do not shorten.

• I bands:

– Distance between A bands of successive sarcomeres.

– Decrease in length.

• H bands:

– Contain only myosin.

– Shorten during contraction..

2)

• Myosin binding site splits ATP to ADP and Pi.

• ADP and Pi remain bound to myosin until myosin heads attach to actin.

• Pi is released, causing the power stroke to occur.

• Power stroke pulls actin toward the center of the A band..

3)

• ADP is released, when myosin binds to a fresh ATP at the end of the power stroke.

• Release of ADP upon binding to another ATP, causes the cross bridge bond to break.

• Cross bridges detach, ready to bind again.

• Synchronous action:

– Only 50% of the cross bridges are attached at any given time..

4)

These cross bridges formation are regulated by tropomyosin/troponin and calcium level.