Tag: structure of muscle

Questions Related to structure of muscle

In the sarcoplasmic reticulum of resting muscle, Ca$^{2+} $ are held together by which protein?

zoology locomotion and movement contractile protein structure of muscle muscles and their structure

  1. Nebulin

  2. Desmin

  3. Calsequestrin

  4. Calmodulin

Show answer
Correct Option: D
Explanation:

In the sarcoplasmic reticulum of resting muscle, Ca2+ are held together by calmodulin. Calmodulin is also called as calcium-modulated protein, is a calcium-binding protein present in the cytoplasm. It is present in all eukaryotic cells.it's the function is to bind calcium ions in resting muscle. when the motor impulse is generated and reached to neuromuscular junctions calcium is released from calmodulin which facilitates muscle contraction.

So, the correct answer is 'Calmodulin'.

Actin binding sites are located on:

zoology locomotion and movement contractile protein structure of muscle muscles and their structure

  1. Troponin

  2. Tropomyosin

  3. Eromyosin

  4. Both (b) and (c)

  5. Both (a) and (b)

Show answer
Correct Option: A

Cross bridges between actin and myosin is broken up by

zoology locomotion and movement contractile protein structure of muscle muscles and their structure

  1. Hydrolysis of AP

  2. Binding of ATP to the myosin head

  3. Binding of calcium to the subunit of troponin

  4. Exposure of tropomyosin

Show answer
Correct Option: B
Explanation:
  • Each myosin (thick) filament is also a polymerized protein. Many monomeric proteins called Meromyosins constitute one thick filament.
  • Each meromyosin has two important parts, a globular head with a short arm and a tail. The globular head is an active ATPase enzyme and has binding sites for ATP and active sites for actin.
  • The globular head of a myosin molecule that projects from a myosin filament in muscle and is held to attach temporarily to an adjacent actin filament and draw it into the A band of a sarcomere between the myosin filaments to form a cross bridge.
  • Cross bridges between actin and myosin are broken up by Binding of ATP to the myosin head and The myosin, releasing the ADP and P1 and muscle goes back to its relaxed state.
  • So, the correct answer is 'Binding of ATP to the myosin head'.

Muscle cells contain _________ protein.

zoology locomotion and movement contractile protein structure of muscle muscles and their structure

  1. Casein

  2. Actin

  3. Myosin

  4. Both B and C

Show answer
Correct Option: D
Explanation:

Muscle is a soft tissue found in most animals. Muscle cells contain protein filaments of actin and myosin that slide past one another, producing a contraction that changes both the length and the shape of the cell. Therefore, (d) is the correct answer. 

Major protein in the thick filaments of skeletal muscle fiber is

zoology locomotion and movement contractile protein structure of muscle muscles and their structure

  1. Myosin

  2. Actin

  3. Tropomyosin

  4. Troponin

Show answer
Correct Option: A
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.
  • Each myosin (thick filament) is made up of Many monomeric proteins called Meromyosins.
  • Hence Major protein in the thick filaments of skeletal muscle fiber is Myosin.
  • So, the correct answer is 'Myosin'.

Myosin filaments are localized in

zoology locomotion and movement contractile protein structure of muscle muscles and their structure

  1. Z-Band

  2. H-Band

  3. A-Band

  4. None of the above

Show answer
Correct Option: C
Explanation:
  • Each myofibril (muscle filament)has alternate dark and light bands on it. 
  • The light bands contain actin and are called I-band or Isotropic band, whereas the dark band called ‘A’ or Anisotropic band contains Myosin.
  • Myosin filaments are also called as Thick filaments.
  • Hence Myosin filaments are localized in A-Band.
  • So, the correct answer is 'A-Band'.

Which one of the following is wrongly matched.

zoology locomotion and movement contractile protein structure of muscle muscles and their structure

  1. Myosin - Contractile protein

  2. Tendon - Connective tissue

  3. Smooth muscle - Involuntary muscle

  4. Red muscle - Myoglobin

  5. Troponin - Fibrous protein

Show answer
Correct Option: E

Component of actin filament of a sarcomere is

zoology locomotion and movement contractile protein structure of muscle muscles and their structure

  1. Myosin and troponin

  2. Troponin and actin

  3. Actin and myosin

  4. Actin, troponin and tropomyosin

Show answer
Correct Option: D
Explanation:
  • Skeletal muscle fiber is made up of two types of filaments. They are thick filament(myosin) and thin filament(actin). 
  • Each actin (thin) filament is made of two ‘F’ (filamentous) actins helically wound to each other. 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 Component of actin filament of a sarcomere is Actin, troponin, and tropomyosin.
  • So, the correct answer is 'Actin, troponin, and tropomyosin'.

Which is wrongly matched?

zoology locomotion and movement contractile protein structure of muscle muscles and their structure

  1. Red muscle-myoglobin

  2. Tendon-connective tissue

  3. Troponin-fibrous protein

  4. Smooth muscle-involuntary muscle

  5. Myosin-contractile protein

Show answer
Correct Option: C
Explanation:
  • The myofibril is composed of two types of filaments. They are thick filament(Myosin) and Thin filament(Actin).
  • 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. In the resting state tropomyosin partially covers myosin binding site on actin. Tropomyosin is a fibrous protein and Troponin is a globular protein.
  • So, the correct answer is 'Troponin-fibrous protein'

Read the statements regarding muscle proteins and identify the correct statements
i. Actin is a thin filament and is made up of two F-actins
ii. Complex protein, tropomyosin is distributed at regular intervals on the troponin
iii. Myosin is a thick filament which is also a polymerized protein
iv. Globular head of meromyosin consists of light meromyosin (LMN)

zoology locomotion and movement contractile protein structure of muscle muscles and their structure

  1. i, iii and iv are correct

  2. i and iii are correct

  3. i, ii and iii are correct

  4. i, ii and iv are correct

  5. ii and iv are correct

Show answer
Correct Option: C
Explanation:
  • Myofibril is made up of two types of filaments.They are thin filament(actin) and thick filament(myosin).
  • 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.
  • Each myosin (thick) filament is also a polymerized protein. Many monomeric proteins called Meromyosins, constitute one thick filament. Globular head of meromyosin consists of Heavy meromyosin (HMM).
  • So, the correct answer is 'i, ii and iii are correct'