Actin‚ a globular protein with a molecular weight of 42-kDa‚ is the most abundant intracellular protein in most eukaryotes (3). It plays important roles in many essential cell biological processes. Actin exists as a monomer called G-actin and as a filament called F-actin‚ a linear chain of G-actin subunits (2). Two F-actin filaments intertwine to form a microfilament‚ one of the three major components of cytoskeleton (2). Microfilament is important for generating cell movement. One mechanism involves
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The Sliding Filament Theory In 1954‚ scientists published two groundbreaking papers describing the molecular basis of muscle contraction. These papers described the position of myosin and actin filaments at various stages of contraction in muscle fibers and proposed how this interaction produced contractile force. Using high-resolution microscopy‚ A. F. Huxley and R. Niedergerke (1954) and H. E. Huxley and J. Hanson (1954) observed changes in the sarcomeres as muscle tissue shortened. They observed
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of the myosin. –Calcium ions bind to troponin‚ exposing the binding site on the actin filament. –The myosin head attaches to the exposed binding site on the actin filament‚ forming a cross-bridge. –The flexing of the cross-bridge pulls the actin filament toward the center of the sarcomere. –An ATP molecule in the reattaches to the ATP binding site on the myosin head. –The myosin head is released from the actin filament’s binding site and the binding site is covered up again. –With the ATP molecule
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cisternae. 11. What is the function of t-tubules? They rapidly move action potentials from the cell surface to the interior of the fiber. 12. What are the different proteins that make up a myofibril? Contractile proteins: Myosin and actin‚ regulatory proteins: tropomyosin and troponin‚
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With each force (a&p) the total force is changed depending on the amount of either A or P forces. 38. Based on the unique arrangement of myosin and actin in skeletal muscle sarcomeres‚ explain why active force varies with changes in the muscle’s resting length. Active force is generated from myosin thick filaments bind to thin actin filaments‚ engaging the cross bridge cycle and ATP hydrolysis. Active force data changes as the resting length of the muscle changes. When the resting length
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their properties are influenced by their reliance on aerobic and anaerobic energy sources. Skeletal muscle is made up of bundles of individual muscle fibres called myocytes. Each myocyte contains many myofibrils‚ which are strands of proteins (actin and myosin) that can grab on to each other and pull. This shortens the muscle and causes muscle contraction. It is generally accepted that muscle fibre types can be broken down into two main types:slow twitch (Type I)muscle fibre and fast twitch (Type
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filaments slide longitudinally past each other producing an overlap between thin and thick filaments. The sliding filaments rely on the reaction between actin and myosin. Calcium ions bind to the troponin complex on the actin filaments and cause the tropomyosin to change the orientation of the actin filament to expose the myosin head binding sites on the actin filament. Glycolysis and aerobic respiration generate adenosine triphosphate (ATP) to sustain muscle contraction. Glycolysis is the decomposition
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protein myosin‚ and the thin filaments are made of the protein actin. The arrangement of the myosin and actin gives skeletal muscle its striated (or striped) appearance. Each section of a myofibril is called a sarcomere‚ and is the functional unit of muscle. How muscles contract is directly related to their structure. The sliding filament theory is an explanation of how muscle contractions occur. This theory states that the actin filaments within the sarcomere slide toward one another during
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structures called actin and myosin filaments. These filaments slide in and out between each other to form a muscle contractions‚ hence the sliding filament theory! The diagram above shows part of a myofibril called a sarcomere. This is the smallest unit of skeletal muscle that can contract. Sarcomeres repeat themselves over and over along the length of the myofibril. The structures involved: Myofibril: A cylindrical organelle running the length of the muscle fibre‚ containing Actin and Myosin filaments
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Full report on BIOINFORMATICS PURIFICACION‚ MARYNOLD V. CHEM 161.1 3L 2nd Semester AY 2012-1013 GROUPMATES: Donato‚ Lualhati M. Diaz‚ Manuelle Marie C. Date Submitted: March 8‚ 2013 Laboratory Instructor: Ms. Herra Grajo I. INTRODUCTION Bioinformatics is the branch of biological science which deals with the study of methods for storing‚ retrieving and analyzing biological data‚ such as nucleic acid (DNA/RNA) and protein sequence‚ structure‚ function‚ pathways and genetic
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