What the difference is between movement and locomotion, and how a cell or an animal moves with cilia, flagella or muscles. The three kinds of muscle, how a skeletal muscle is built from bundles, fibres and myofibrils, and what the sarcomere and its two proteins, actin and myosin, look like. It covers the unit of the Indian syllabus (NCERT, NEET) and the matching topic of A-Level, IB and AP.
3 lessons, about 1 h 20 min3 simulations11 problems3 practice questionsPython in every lesson
A child runs after a ball, and the hairs in her windpipe sweep dust upward. Both are movements, but only running carries her from one place to another. This lesson separates movement from locomotion, and describes the ways in which a cell or an animal moves: with cilia, with a flagellum, or with muscles.
Muscle is a tissue that can contract. The body has three kinds: skeletal muscle with stripes under voluntary control, smooth muscle in the walls of hollow organs, and cardiac muscle in the heart. A skeletal muscle is built from bundles of fibres, and each fibre is a single cell with many nuclei that holds thread-like myofibrils.
A myofibril is striped because thin actin filaments and thick myosin filaments are arranged in a regular pattern. The part between two Z lines is the sarcomere, the unit of contraction. Actin carries tropomyosin and troponin, and the head of a myosin molecule is an enzyme that splits ATP.
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