Cooperation and selfishness both benefit the donor and therefore should be favoured by natural selection.

TLS Online TPP Program

#Id: 8370

#Unit 2. Cellular Organization

In the absence of ATP, the myosin head is firmly attached to the actin filament. 

TLS Online TPP Program

#Id: 8371

#Unit 2. Cellular Organization

In the presence of ATP,  myosin head releases from the actin filament. 

TLS Online TPP Program

#Id: 8372

#Unit 2. Cellular Organization

Thick-filament regulation

Myosin-dependent mechanism regulate contraction in smooth muscle and non-muscle cells.

TLS Online TPP Program

#Id: 8373

#Unit 2. Cellular Organization

In vertebrate smooth muscle, phosphorylation of the myosin regulatory light chain activates contraction in Ca2+ dependent manner.

TLS Online TPP Program

#Id: 8374

#Unit 2. Cellular Organization

When the Ca2+ levels drop:

Myosin LC is dephosphorylated by MLC phosphatase, causing muscle relaxation.

TLS Online TPP Program

#Id: 8375

#Unit 2. Cellular Organization

Ca2+ dependence of vertebrate skeletal muscle contraction, depends on :

action potential

specialized accessory proteins Tropomyosin,

Troponin (T, I, and C)