Tag: contractile protein

• Skeletal muscle fiber is made up of two types of filaments. They are thick filament (myosin) and thin filament (actin). Contraction of a muscle fiber takes place by the sliding of the thin filaments over the thick filaments.
  
• Myosin (thick) filament is also a polymerized protein. Many monomeric proteins called meromyosins constitute one thick filament. 
  
• Each actin (thin) filament is made of two ‘F’ (filamentous) actins helically wound to each other. Each ‘F’ actin is a polymer of monomeric ‘G’ (Globular) actins. Two filaments of another protein, tropomyosin also run close to the ‘F’ actins throughout its length. A complex protein troponin is distributed at regular intervals on the tropomyosin.
  
• Hence, the important muscles proteins that help in the movement are actin and myosin, troponin and tropomyosin.
• So, the correct answer is 'All of the above'.

• Skeletal muscle fiber is made up of two types of filaments. They are thick filament (myosin) and thin filament (actin). Contraction of a muscle fiber takes place by the sliding of the thin filaments over the thick filaments.
  
• Myosin (thick) filament is also a polymerized protein. Many monomeric proteins called meromyosins constitute one thick filament. 
  
• Each actin (thin) filament is made of two ‘F’ (filamentous) actins helically wound to each other. Each ‘F’ actin is a polymer of monomeric ‘G’ (Globular) actins. Two filaments of another protein, tropomyosin also run close to the ‘F’ actins throughout its length
•  In the resting state a subunit of troponin masks the active binding sites for myosin on the actin filaments.
  
• So, the correct answer is 'Troponin'.

• Myofibrils are composed of two types of filaments i.e thin filament (actin) and thick filament (myosin).
  
• Actin filaments are thinner as compared to the myosin filaments, hence are commonly called thin and thick filaments respectively
  
• Each myosin (thick) filament is a polymerized protein. Many monomeric proteins called meromyosins constitute one thick filament (Myosin).
  
• Hence thick filaments in muscles are polymerized proteins of meromyosin.
• So, the correct answer is 'Meromyosin'.

Thin filaments of myofibril contain one filament of actin and two filaments of troponin, along with tropomyosin protein.

• The myofibril is composed of two types of filaments. They are thick filament(Myosin) and Thin filament(Actin).
  
• Increase in Ca++ level leads to the binding of calcium with a subunit of troponin i.e troponin-C on actin filaments and thereby remove the masking of active sites for myosin. Utilizing the energy from ATP hydrolysis, the myosin head now binds to the exposed active sites on actin to form a cross bridge.
  
• Each myosin (thick) filament is also a polymerized protein. Many monomeric proteins called Meromyosins constitute one thick filament. Each meromyosin has the globular head which is an active ATPase enzyme and has binding sites for ATP and active sites for actin. Hence ATPase activity in muscle fibre lies with Head of heavy meromyosin.
• So, the correct answer is 'Head of heavy meromyosin'.

Actin belongs to the family of globular multifunctional protein that forms microfilaments in muscle fibers. The associated proteins along with actin found in thin filaments are troponin and tropomyosin.however the binding sites are located in meromyosin.

• Myoglobin is a protein found in muscles of almost all mammals that binds to both iron and oxygen. 
• It is also made up of heme and globin protein. 
• The main function of myoglobin is binding to oxygen and carrying it to different muscle tissues.
• So, the correct answer is 'Muscles'.

The layers of stomach wall include serosa, muscularis, submucosa, and mucosa these are involuntary in nature and show the presence of cell junctions also, the muscularis layer shows branched and multinucleated appearance.