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What is one of the functional units of a myofibril?
sarcomere
What do sarcomere contain?
Sarcomeres are composed of actin (thin filaments) and myosin (thick filaments).
Interactions between actin and myosin filaments of the sarcomere are responsible for what?
muscle relaxation
Myofibrils are constructed of overlapping strands of protein polymers?
Actin and Myosin. A conglomeration of actin fibrils and myosin filaments form a myofibril body called a sarcomere.
Why does band stay the same length when the sarcomere shortens?
the A band stays the same length because it is the length of the myosin filaments, and all the myosin does it sit there while actin slides past it.
What is the zone of overlap?
The zone of overlap is the point where actin myofilaments overlay the myosin myofilaments as it (actin) gets pulled towards the m-line (mid-point of sarcomere). The zone of overlap increases during muscle contraction, resulting in the shortening of the muscle.
What is one of the functional units of a myofibril?
sarcomere
What happens to a sarcomere when muscle length changes?
1. Arrangement of thick and thin filaments: In each sarcomere two sets of actin filaments extend partway toward the center. The myosin filaments are arranged such that they partially overlap the actin filaments. Myosin heads on each side point away from the center of the sarcomere.2. During contraction, the interaction of myosin heads with the actin filaments pulls the thin filaments toward the center of the sarcomere. The actin and myosin filaments slide past each other.3. Cross-bridges = attachement betwn myosin heads and binding sites on actin filaments.4. When a muscle cell is stimulated, myosin heads are energized by ATP. They attach to adjacent actin filaments, and tilt in a short "power stroke" toward the center of the sarcomere. Each power sroke requires an ATP. With many power strokes in rapid succession, the actin filaments are made to slide past the myosin filaments.
What is a actin or myosin containing strucutre?
The basic unit of muscular contraction; the sarcomere.
What do sarcomere contain?
Sarcomeres are composed of actin (thin filaments) and myosin (thick filaments).
Interactions between actin and myosin filaments of the sarcomere are responsible for what?
muscle relaxation
What are the 3 sections along the length of sarcomere?
The three sections along the length of a sarcomere are the A band, the I band, and the H zone. The A band is the dark region in the center of the sarcomere that contains both thick and thin filaments, while the I band is the light region at the ends of the sarcomere that contains thin filaments only. The H zone is the region in the center of the sarcomere where only thick filaments are present.
What is the dark staining area of a sarcomere?
It is a section of the Sarcomere that stretches from one end of the Myosin filament to the other, and also includes parts of the Actin filaments that overlaps it.
What is the crossbridge cycle?
The crossbridge cycle is the cyclical formation of links between actin and myosin. This results in the sliding of thin filaments towards the M line of a sarcomere. The myosin head undergoes conformation changes which allows it to swivel back and forth. In its low energy form, myosin has a low affinity for actin. The ATP prepares myosin for binding with actin by moving it to its high energy form position. When myosin contracts, it has a high affinity for actin.
What are the proteins are involved in muscle contraction?
Actin and myosin
Myofibrils are constructed of overlapping strands of protein polymers?
Actin and Myosin. A conglomeration of actin fibrils and myosin filaments form a myofibril body called a sarcomere.
Why does band stay the same length when the sarcomere shortens?
the A band stays the same length because it is the length of the myosin filaments, and all the myosin does it sit there while actin slides past it.
