Tag: muscles and their structure

Questions Related to muscles and their structure

Actin binding sites are located over

zoology skeleton and movements contractile protein structure of muscle muscles and their structure

  1. Troponin

  2. Tropomyosin

  3. Meromyosin

  4. Creatnine

  5. Both A and B

Show answer
Correct Option: C
Explanation:
  • 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 is an active ATPase enzyme and has binding sites for ATP and active sites for actin.
  • Hence actin binding sites are located over meromyosin'.
  • So, the correct answer is 'Meromyosin'.

Identify the thick myofilament from the given contractile proteins.

zoology skeleton and movements contractile protein structure of muscle muscles and their structure

  1. Troponin 

  2. Myosin

  3. Tropomyosin

  4. Actin

Show answer
Correct Option: B
Explanation:
  • Skeletal muscle fiber is made up of two types of filaments. They are thick filament and thin filament.
  • Thick filament is made up of a protein called 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 made up of Many monomeric proteins called Meromyosins.
  • Hence the thick myofilament from the given contractile proteins is myosin.
  • So.the correct answer is 'Myosin'.

In skeleton muscle Z-line is connected to.

zoology skeleton and movements contractile protein structure of muscle muscles and their structure

  1. Actin

  2. Myosin

  3. Tropomyosin

  4. Hensen's line

Show answer
Correct Option: A
Explanation:

  • Each myofibril consists of a series of contractile units (sarcomeres) connected at a protein border (the Z line).
  •  Thin filaments(actin) of adjacent sarcomeres are present in the Z line between the thin filaments are thick filaments(myosin). 
  • The protein tropomyosin winds around the thin filaments and covers the myosin binding sites. Hence, In skeleton muscle, Z-line is connected to actin.
So, the correct answer is 'actin'.

Major protein in thick filaments of skeletal muscle fibre is?

zoology skeleton and movements contractile protein structure of muscle muscles and their structure

  1. Myosin

  2. Actin

  3. Tropomyosin

  4. Troponin

Show answer
Correct Option: A
Explanation:

  • The main contractile components of a muscle fibre include:
  •  Thick filaments - The major protein of a thick filament is myosin. 
  • Thin filaments - The major proteins of a thin filament include actin, as well as troponin and tropomyosin. Hence, Major protein in thick filaments of skeletal muscle fibre is myosin.
So, the correct answer is 'myosin'.