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Do the heads of myosin molecules contact the actin filaments when a muscle is relaxed?
No, the heads of myosin molecules do not contact the actin filaments when a muscle is relaxed. In a relaxed state, the binding sites on actin are blocked by tropomyosin, preventing myosin heads from attaching. When calcium ions are released during muscle contraction, they bind to troponin, causing a conformational change that moves tropomyosin and exposes the binding sites for myosin, allowing contraction to occur.
What else can I help you with?
Does Tropomyosin molecules move and expose specific sites on myosin filaments?
Yes, tropomyosin molecules block specific binding sites on actin filaments in relaxed muscle. When calcium ions bind to troponin, it causes a conformational change in tropomyosin, exposing the binding sites on actin, which allows myosin heads to bind and initiate muscle contraction.
What is point of attachment for thin filaments?
Thin filaments in muscle cells attach to the Z-discs, which are structures that anchor the filaments and help in muscle contraction. The Z-discs are located at the ends of the sarcomere, which is the basic contractile unit in muscle fibers. The attachment of thin filaments to the Z-discs allows for the sliding mechanism that is essential for muscle contraction.
Which of the following become connected by myosin cross-bridges during muscle contraction A) thin filaments and thick filaments B) thin filaments and t-tubules C) thick filaments and titin filame?
Interactions between actin and myosin filaments of the sarcomere are responsible for muscle contractions. The I bands contain only thin (actin) filaments, whereas the A bands contain thick (myosin) filaments.
What are two myofilaments that slide past one another to allow muscle cells to contract?
The two myofilaments that slide past one another to enable muscle contraction are actin and myosin. Actin makes up thin filaments while myosin forms thick filaments. During muscle contraction, myosin heads attach to actin filaments and pull them towards the center of the sarcomere, causing the muscle to shorten.
Where are the myosin filaments found?
Myosin filaments are found in muscle cells, specifically in the thick filaments that make up the myofibrils within the muscle fibers. They are a key component of the sarcomeres, the functional unit of the muscle that is responsible for muscle contraction.
When a muscle is relaxed are there only thin filaments in the center of the sarcomere?
Yep, you got it.
Does Tropomyosin molecules move and expose specific sites on myosin filaments?
Yes, tropomyosin molecules block specific binding sites on actin filaments in relaxed muscle. When calcium ions bind to troponin, it causes a conformational change in tropomyosin, exposing the binding sites on actin, which allows myosin heads to bind and initiate muscle contraction.
What is composed of myosin?
Myosin is a protein found in muscle cells that plays a key role in muscle contraction. It consists of long molecules called myosin filaments, which interact with actin filaments to generate the force needed for muscle movement.
Are there more thick filaments than thin filaments in smooth muscle?
There more thin filaments than thick filaments in smooth muscle. The ratio is of the thin to thick filaments in the smooth muscle is approximately 15:1.
What are the events that influence the width of each sarcomere when a muscle being contracted and relaxed?
During muscle contraction, the sarcomere width decreases due to the overlapping of actin and myosin filaments. This is caused by the sliding of the filaments past each other. When the muscle relaxes, the sarcomere width increases as the filaments slide back to their original positions. The regulation of calcium ions and ATP availability also play a role in influencing the width of each sarcomere during muscle contraction and relaxation.
What is the difference between the contracted muscle and a relaxed muscle?
contracted muscle and relaxed muscle whats are the difference? contracted muscle means its very very contracted and relaxed muscle means its very very relaxed
What are the 3 types of filaments within a muscle and what protein makes up each filament?
The three types of filaments within a muscle are thin filaments, thick filaments, and elastic filaments. Thin filaments are primarily composed of the protein actin, while thick filaments are made up of myosin. Elastic filaments, which help maintain the structure and elasticity of the muscle, are primarily composed of the protein titin. These filaments work together to facilitate muscle contraction and relaxation.
DO actin and myosin come from muscle fiber?
Yes, actin and myosin are protein filaments found within muscle fibers. Actin is responsible for thin filaments and myosin for thick filaments in muscle contraction.
How does a muscle contact according to the sliding-filament model of muscle contraction?
When skeletal (or cardiac) muscle contracts, the thin and thick filaments in each sarcomereslide along each other without their shortening, thickening, or folding.
The filaments are arranged along the muscle fiber in units called?
Actin filaments
What muscle cell filaments come closer together when the sarcomere shortens?
thin filaments
Myosin cross bridges attach to active sites of?
actin filaments in muscle cells during muscle contraction.
