Understanding Meromyosin Structure
Meromyosin is a fragment of myosin, a crucial protein involved in muscle contraction. To comprehend what a meromyosin molecule contains or lacks, we must examine its structure closely.
Components of Myosin
- Myosin is typically composed of three main parts:
- Head: This portion binds to actin and has ATPase activity, facilitating muscle contractions.
- Tail: The tail region helps in dimerization and interacts with other myosin molecules, providing structural integrity to thick filaments.
- Arm: The arm connects the head to the tail, allowing flexibility and movement during contraction.
Defining Meromyosin
- Meromyosin is derived from myosin through limited proteolysis. It is generally divided into two parts:
- Heavy meromyosin (HMM): Contains the head and part of the tail.
- Light meromyosin (LMM): Comprises the remaining tail region.
Why Option B is Correct
- When examining the components of meromyosin, the term "trunk" is not a recognized structure within myosin or meromyosin.
- Therefore, in the context of the options provided:
- Arm: Present in meromyosin as it connects the head to the tail.
- Tail: Present in the form of heavy meromyosin.
- Head: Present as part of heavy meromyosin.
Conclusion
In summary, the correct answer is option 'B' (trunk), as meromyosin does not contain any structure referred to as a "trunk." Understanding these components is essential for grasping the mechanics of muscle contraction in the NEET syllabus.