The cross bridge cycle is a series of molecular events that occur after excitation of the sarcolemma. what is a cross bridge? a. troponin bound to tropomyosinb. calcium bound to troponinc. atp bound to a myosin headd. a myosin head bound to actin

A myosin head bound to actin

Explanation:

Cross bridge cycling explains the sliding filament theory according to which thin and thick filament slide against each other for muscle contraction. The two myosin heads extend form the thick filament. One myosin head has binding site for ATP and other head has binding site for actin from thin filament.

When myosin head binds to actin a cross bridge is formed. When ATP binds to the other head the bridge dissociates. Actin binding site is free and myosin tries to bind with other actin during which ATP is hydrolysed into ADP and Pi. Myosin along with the ADP and free Pi successfully binds to another actin molecule. The cross bridge formed generates a powerful force and ADP and Pi are displaced from it. The cross bridge is now free again for binding of next ATP molecule and the cycle continues.

1. amino acid refers to the fundamental building block of proteins, comprising of an amino group and a carboxyl group.

2. catalyst refers to any substance, which increases the rate of chemical reaction without being used up in the reaction.

3. a complex molecule containing he genetic code is dna or deoxyribonucleic acid.

4. an enzyme refers to a molecule of protein, which is unique in accelerating up a particular chemical reaction in the biological systems.

5. nucleic acid refers to an sequence of sugars, phosphates, and nitrogenous bases, for example, dna and rna.

6. a protein refers to a large, composite organic molecule comprising of a huge number of amino acids associated together with the of peptide bonds.

7. rna refers to a nucleic acid that takes part in the production of proteins.

8. substrate refers to a compound, which takes part in a chemical reaction, and is chemically modified by the reaction.