BIOL273 Chapter Notes - Chapter 3: Titin, Sarcomere, Muscle Contraction
11 Sep 2016
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Document Summary
The arrangement of thick and thin filaments creates a pattern: each repeating unit sarcomere. Z-disk: zigzag protein structures that serve as the attachment site of thin filaments- one sarcomere has 2 z disks. I-band: lightest colour bands- where there are only thin filaments- z disk is in the middle of the i band. A-band: darkest part of the sarcomere- where there are thick and thin filaments. H-zone: a little lighter than a-band- there are only thick filaments. M-line: attachment side for thick filaments- the center of the sarcomere. Titin: is a large elastic protein (an accessory protein) that stabilizes the position of the contractile filaments and returns stretched muscles to their resting length with its elasticity. Titin is helped by nebulin: an inelastic protein (also accessory) that lies along the thin filaments and attaches to the z disk. It helps align the thin actin filaments of the sarcomere.
