ATP's function in muscle contraction?

Question

What is the role of ATP in muscle contraction and what are the functions of creatine phosphate and glycogen?

Please be as detailed as possible.

Answer 1

Myosin (which has ADP and inorganic phosphate bound to its nucleotide binding pocket and is in a ready state) binds to the newly uncovered binding sites on the thin filament. Myosin is now bound to actin in the strong binding state. The release of ADP and inorganic phosphate causes the myosin head to turn, causing a ratchet movement (actin acts as a cofactor in the release of inorganic phosphate, expediting the release). This will pull the Z-bands towards each other, thus shortening the sarcomere and the I-band.
ATP binds myosin, allowing it to release actin and be in the weak binding state. (A lack of ATP makes this step impossible, resulting in the rigor state characteristic of rigor mortis.) The myosin then hydrolyzes the ATP and uses the energy to move into the "****** back" state while releasing ADP and inorganic phosphate. In general, evidence (predicted and in vivo) indicates that each skeletal muscle myosin head moves 10-12 nm each power stroke, however there is also evidence (in vitro) of variations (smaller and larger) that appear specific to the myosin isoform.

Phosphocreatine, also known as creatine phosphate or PCr, is a phosphorylated creatine molecule that is an important energy store in skeletal muscle. It is used to generate ATP from ADP, forming creatine for the 2 to 7 seconds following an intense effort. This reaction is reversible and it therefore acts as a spatial and temporal buffer of ATP concentration. Phosphocreatine plays a particularly important role in tissues that have high, fluctuating energy demands such as muscle and brain. Creatine phosphate is synthesized in the liver, and transported to the muscle cells for storage.

Glycogen (commonly known as animal starch although this name is inaccurate) is a polysaccharide that is the principal storage form of glucose (Glc) in animal cells. Glycogen is found in the form of granules in the cytosol in many cell types, and plays an important role in the glucose cycle. Glycogen forms an energy reserve that can be quickly mobilized to meet a sudden need for glucose, but one that is less compact than the energy reserves of triglycerides. Only the glycogen stored in the liver can be made accessible to other organs, and these hepatocytes have the highest concentration of it - up to 8% of the fresh weight in well fed state, or 100–120 g in an adult. In the muscles, glycogen is found in a much lower concentration (1% of the muscle mass), but the total amount exceeds that in liver. Small amounts of glycogen are found in the kidneys, and even smaller amounts in certain glial cells in the brain and white blood cells.

Answer 2

ATP supplies the energy for muscle contraction.

Answer 3

glycogen breaks down to glucose, which undergoes glycolysis.....forming nadh and pyruvate...... pyruvate enters the citric acid cycle forming nadh and fadh2. nadh and fadh2 donate electron to the electron transport chain which creates more ATP

Answer 4

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