Tag: structure of muscle

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

Choose the correct answer from the alternatives given.
The enormous diversity of protein molecules is mostly due to the diversity of:

  1. Amino groups on the amino acids

  2. K groups on the amino acids

  3. R groups on the amino acids

  4. Peptide bonds
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

There are 20 amino acids known. All the amino acids follow the basic structure. It consists of a carbon atom in the middle surrounded by three chemical bases.

Two out of three bases are the amino (NH$ _2$ group) and the carboxylic group (COOH). The third group is a simple hydrogen atom present in all the amino acids.
The fourth group is called an R group that determines the nature of the amino acid. This R group can be as simple as a hydrogen atom and may also contain complex rings. On the basis of the R group, the amino acid can be polar or non-polar, acidic or basic or neutral.
Thus the enormous diversity of protein molecules is mostly due to the diversity in the R group.
So, the correct option is 'R groups on the amino acids'.

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

State whether the following statements are true or false.
Actin is present in thin filament.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Skeletal muscle is composed of muscle fibres which have smaller units called myofibrils. There are three types of proteins make up each myofibril; they are contractile, regulatory and structural proteins. By contractile proteins, we mean actin (thin filament) and myosin (thick filament).

So, the correct option is 'True'.

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'.