Tag: structure of muscle

Questions Related to structure of muscle

Thick filaments in muscles are polymerised proteins of

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

  1. Meromyosin

  2. Actin

  3. Troponin

  4. Tropomyosin

  5. Keratin

Show answer
Correct Option: A
Explanation:
  • 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'.

 The thin filaments of myofibril contain  __(A)_ actin and two filaments of (B) protein along with  (C)_  protein for masking binding site for myosin. 

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

  1. A - 1F B - troponin C - Tropomyosin

  2. A - 1F B - tropomyosin C - troponin

  3. A - 2F B - troponin C - tropomyosin

  4. A - 2F B - tropomyosin C - troponin

Show answer
Correct Option: A
Explanation:

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

So, the correct option is 'A - 1F B - troponin C - Tropomyosin'.

ATPase activity in muscle fibre lies with

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

  1. Light meromyosin

  2. Head of heavy meromyosin

  3. Troponin

  4. Short arm of heavy meromyosin

Show answer
Correct Option: B
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 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 binding sites are located on:

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

  1. troponin

  2. tropomyosin

  3. meromyosin

  4. both (b) and (c)

Show answer
Correct Option: C
Explanation:

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.

So, the correct option is 'meromyosin'.

Which of the following proteins is found in the thick filaments of skeletal muscle?

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

  1. Actin

  2. Troponin

  3. Myosin

  4. Tropomyosin

Show answer
Correct Option: C
Explanation:
A skeletal muscle is made up of different types of proteins. The thick filaments are made up of myosin while the thin filament is made up of three proteins actin, troponin, and tropomyosin. So, the correct answer is 'Myosin'.

Myoglobin is found in?

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

  1. Muscles

  2. Blood

  3. Lungs

  4. RBCs

Show answer
Correct Option: A
Explanation:

  • 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'.

Read the following statement (A-D) with regards to muscles.


Choose the correct option.

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

  1. I-bands are isotropic bands and made by actin filaments

  2. A-bands are anisotropic bands and made by both actin and myosin filaments

  3. In between I-bands thin fibrous M-line is present

  4. In between A-bands, thin fibrous M-line is present

Show answer
Correct Option: A

Select the option where the property describing muscle fibres is not associated with wall of stomach.

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

  1. Presence of actin and myosin fibrils

  2. Branched, multinucleated appearance

  3. Presence of cell junctions

  4. Involuntary nature

Show answer
Correct Option: A
Explanation:

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.

However, the presence of actin and myosin fibrils is seen in smooth muscles.
So, the correct answer is 'Presence of actin and myosin fibrils'.

Which fibres, contractile in nature are found in muscles?

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

  1. White fibres

  2. Myofibrils

  3. Micro fibrils

  4. Elastic fibres

Show answer
Correct Option: B
Explanation:

Contractile fibres are those fibres which are capable in contraction of the muscles.

 Fibres Nature 
 White fibres (form of mature connective tissue)  Ineslastic
 Myofibrils (skeletal muscle)  Contractile
 Micro fibrils (surface of primary cell wall)  elastic
 Elastic fibres (bundle of connective tissue)  elastic

So, the correct  option is 'Myofibrils'

Which of the following are the regulatory protein in the  muscle contraction?

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

  1. Troponin and tropomyosin

  2. Troponin and actin

  3. Myosin and tropomyosin

  4. Actin and tropomyosin

Show answer
Correct Option: A
Explanation:
  • Actin and myosin are the contractile proteins, and they interact with each other, causing contraction, while troponin and tropomyosin are regulatory proteins that regulate the interaction between actin and myosin. 
  • Myofilaments(actin and myosin) are packed in functional units of striated muscle referred to as sarcomeres. 
  • Hence, Troponin and tropomyosin are the regulatory protein in muscle contraction.
  • So, the correct answer is 'Troponin and tropomyosin'.