Tag: muscles and their structure

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

Actin binding sites are located over

  1. Troponin

  2. Tropomyosin

  3. Meromyosin

  4. Creatnine

  5. Both A and B
Reveal answer Fill a bubble to check yourself
C Correct answer
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'.
Multiple choice zoology skeleton and movements contractile protein structure of muscle muscles and their structure

Identify the thick myofilament from the given contractile proteins.

  1. Troponin

  2. Myosin

  3. Tropomyosin

  4. Actin
Reveal answer Fill a bubble to check yourself
B Correct answer
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'.
Multiple choice zoology skeleton and movements contractile protein structure of muscle muscles and their structure

In skeleton muscle Z-line is connected to.

  1. Actin

  2. Myosin

  3. Tropomyosin

  4. Hensen's line
Reveal answer Fill a bubble to check yourself
A Correct answer
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'.

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

Major protein in thick filaments of skeletal muscle fibre is?

  1. Myosin

  2. Actin

  3. Tropomyosin

  4. Troponin
Reveal answer Fill a bubble to check yourself
A Correct answer
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'.