Tag: structure of muscle

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

Thick filaments in muscles are polymerised proteins of

  1. Meromyosin

  2. Actin

  3. Troponin

  4. Tropomyosin

  5. Keratin
Reveal answer Fill a bubble to check yourself
A Correct answer
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'.
Multiple choice zoology locomotion and movement contractile protein structure of muscle muscles and their structure

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

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

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

ATPase activity in muscle fibre lies with

  1. Light meromyosin

  2. Head of heavy meromyosin

  3. Troponin

  4. Short arm of heavy meromyosin
Reveal answer Fill a bubble to check yourself
B 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 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'.
Multiple choice zoology locomotion and movement contractile protein structure of muscle muscles and their structure

Actin binding sites are located on:

  1. troponin

  2. tropomyosin

  3. meromyosin

  4. both (b) and (c)
Reveal answer Fill a bubble to check yourself
C Correct answer
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'.

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

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

  1. Actin

  2. Troponin

  3. Myosin

  4. Tropomyosin
Reveal answer Fill a bubble to check yourself
C Correct answer
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'.
Multiple choice zoology locomotion and movement contractile protein structure of muscle muscles and their structure

Myoglobin is found in?

  1. Muscles

  2. Blood

  3. Lungs

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

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

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


Choose the correct option.

  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
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

I-bands (isotropic) contain only thin actin filaments, which is why they appear lighter under a microscope compared to the A-bands.

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

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

  1. Presence of actin and myosin fibrils

  2. Branched, multinucleated appearance

  3. Presence of cell junctions

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

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

Which fibres, contractile in nature are found in muscles?

  1. White fibres

  2. Myofibrils

  3. Micro fibrils

  4. Elastic fibres
Reveal answer Fill a bubble to check yourself
B Correct answer
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'

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

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

  1. Troponin and tropomyosin

  2. Troponin and actin

  3. Myosin and tropomyosin

  4. Actin and tropomyosin
Reveal answer Fill a bubble to check yourself
A Correct answer
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'.