Tag: contractile protein

Questions Related to contractile protein

The monomeric actin is called as

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

  1. F- actin

  2. M- actin

  3. G- actin

  4. N- actin

Show answer
Correct Option: C
Explanation:

Actin is the thin filament of the muscles. It is a polymer made of many monomers. The monomers of actin are globular in shape and hence called Globular-actin or G-actin. Monomers together form straight chains of polymer action. The polymer action is called F-actin.

So the correct option is C.

In a muscle fibre

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

  1. Sacrolemma is connective tissue holding the myofibrils together

  2. T system contains calcium storage sacs

  3. Both filaments have cross-bridges

  4. All of the above

Show answer
Correct Option: B
Explanation:
Terminal cisternae are enlarged areas of the sarcoplasmic reticulum surrounding the transverse tubule because terminal cisternae ensure rapid calcium delivery, they are well developed in muscles that contract quickly such as fast-twitch skeletal muscle.
So, the T system contains calcium storage sacs.

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

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

  1. Amino groups on the amino acids

  2. K groups on the amino acids

  3. R groups on the amino acids

  4. Peptide bonds

Show answer
Correct Option: C
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'.

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

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

  1. True

  2. False

Show answer
Correct Option: A
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'.

Major protein constituent of muscle fibre is?

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

  1. Actin

  2. Myosin

  3. Tropomyosin

  4. Reticulin

Show answer
Correct Option: B

Actin binding sites are located over

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

  1. Troponin

  2. Tropomyosin

  3. Meromyosin

  4. Creatnine

  5. Both A and B

Show answer
Correct Option: C
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'.

Identify the thick myofilament from the given contractile proteins.

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

  1. Troponin 

  2. Myosin

  3. Tropomyosin

  4. Actin

Show answer
Correct Option: B
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'.

In skeleton muscle Z-line is connected to.

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

  1. Actin

  2. Myosin

  3. Tropomyosin

  4. Hensen's line

Show answer
Correct Option: A
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'.

Major protein in thick filaments of skeletal muscle fibre is?

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

  1. Myosin

  2. Actin

  3. Tropomyosin

  4. Troponin

Show answer
Correct Option: A
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'.