Tag: muscles and their structure

Questions Related to muscles and their structure

Each actin filament is made of

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

  1. 2 'G' Actin molecules

  2. 2 F Actin molecules

  3. 1 F Actin molecules

  4. 1 G Actin molecules

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Correct Option: B
Explanation:

Actin is the protein which helps in the muscle contraction. It present in two forms G actin (globular actin) and F actin (filament actin). In muscles, actin filament is formed by the two long strand of bead-like twisted actin molecule. 

So, the correct answer is '2 F Actin molecules'.

Contractile unit of muscle fibres is

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

  1. Muscle fibre

  2. Sacromere

  3. Myofibril

  4. Sacrosome

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Correct Option: B
Explanation:

The entire cross section of the muscle fibre is taken up by long, cylindrical strands of contractile proteins called myofibrils. One myofibril is divided into segments called sarcomeres. These are the contractile units of a muscle. A dark stripe called a Z disc marks the ends of one sarcomere and the beginning of the next.

Contractile proteins include:

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

  1. Troponin

  2. Tropomyosin

  3. Actin and myosin

  4. All the three

Show answer
Correct Option: C
Explanation:

The main components of protein in muscle is actin and myosine that form thin and thick fibers respectively.


The troponin and tropmyosine come under the category of regulatory proteins that regulate the process of muscle contraction.

for example troponin binds with tropomysosine to inhibit actin and myosine interaction during relaxation stage.

Hence the correct answer is (C). 

The important muscle proteins that help in movement are

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

  1. Actin and myosin

  2. Tropomyosin

  3. Troponin

  4. All of these

Show answer
Correct Option: D
Explanation:

Actin and myosin are the structural filaments that play the main role in muscle contraction by sliding filament theory.

Troponin and tropomyosin are the regulatory proteins that regulate the rate of attachment of myosin heads to actin. Hence they also play an important role in muscle contraction and its movement.
Troponin regulate availability of active sites of actin by attaching with Ca++
So the correct option is D.

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:

Actin is the thin filaments of the muscles. They are a polymer of G-actin monomers arranged in chains and two such chains are wound in a helix. So, the given statement is true.

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

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Correct Option: B