A. Cells have characteristic structures and functions that make them distinctive.
B. Processes in a cell can be classified broadly as growth, maintenance, reproduction, and homeostasis.
C. Life can be organized in a functional and structural hierarchy ranging from cells to the biosphere.
D. Most multicellular organisms are composed of organ systems whose structures reflect their particular function.
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This Khan Academy video describes the structure of muscle cells. The tutorial details the muscle cell from the macro skeletal muscle to the individual cell of the muscle, called the myofiber. The functions of actin and myosin and how they cause muscles to contract are also explained.
Type: Tutorial
This tutorial will help students understand the process of muscle contraction. A muscle contains many muscle fibers and each fiber contains a bundle of 4-20 myofibrils. Each fibril is striated and these striations are produced by the arrangement of thick and thin filaments, called actin and myosin. The contraction and relaxation of these actin and myosin filaments help muscles move.
Type: Tutorial