Question

All parts needed. will give thumbs up for ALL parts. short answers needed.

1. The action potential has just come down the T-tubule of a muscle cell a. Describe the molecular events that now take place to cause ultimately contraction and finally relaxation of the muscle cell. Name the molecular players involved including receptors, calcium-binding proteins, organelle involved and contractile proteins. Abbreviations are acceptable. b. Describe how ATP and conformation changes in myosin dictate myosin-actin cross-bridge cycle. C. Skeletal muscle tension (force) can vary with its length. Why does active tension (force) start dropping once maximum force is achieved and muscle length starts increasing further? At much longer muscle lengths, why does the overall (total) tension start increasing again?

Answer 1

• The sliding filament theory describes the contraction and relaxation of the muscle which needs ca2+ ion. The molecular players are tropomyosin, troponin complex, calmodulin, myosin and actin protein.
• Atp hydrolysis causes the myosin head to move along the actin and slide. The myosin head again attached to the acin filament.
• The muscle tension varies with the length. With the maximum strain the muscle fibre the contraction of the muscle fibre becomes smaller. So the length starts increasing. As the muscle fibre is relaxed again the stress strain cycle starts in the muscle as we put pressure by exercise.
• Glycolysis happens in the cytoplasm and the glucose molecule get converted into pyruvate with a production of 8 atp. krebs cycle happens in the mitochondria the acetyl co a molecule get converted into a series of acids which starts from oxalo acetic acid. it produces 2 atp and other products are processed through ets. Ets happens in the mitochondria. it produces 34 atp in total.
• Fat enters as fatty acid into the mitochondria and the oxidation happens. It enters through a shuttle system known as carnitine shuttle system.