Which of the following statement is INCORRECT ?

Options

A. Each actin filament is made of two G actin
B. Each F actin is a polymer of G actin
C. Troponin is a complex protein distributed at regular intervals on tropomyosin
D. Tropomyosin run close to F -actin along its length

Answer

To determine which statement is incorrect, we will analyze each option provided in the question step by step.

### Step 1: Analyze Option 1
**Statement:** Each actin filament is made of 2G actin.

**Analysis:**
- Actin filaments, also known as F-actin (filamentous actin), are not made of "2G actin." Instead, they are composed of multiple G-actin (globular actin) monomers that polymerize to form long helical chains. Therefore, this statement is incorrect.

### Step 2: Analyze Option 2
**Statement:** Each F-actin is a polymer of G-actin.

**Analysis:**
- This statement is correct. F-actin is indeed a polymer formed from G-actin monomers. Each G-actin molecule can bind to others to form a filamentous structure.

### Step 3: Analyze Option 3
**Statement:** Troponin is a complex of protein distributed at regular intervals of tropomyosin.

**Analysis:**
- This statement is also correct. Troponin is a protein complex that interacts with tropomyosin and is found at regular intervals along the actin filament, playing a crucial role in muscle contraction.

### Step 4: Analyze Option 4
**Statement:** Tropomyosin runs close to actin along its length.

**Analysis:**
- This statement is correct as well. Tropomyosin is a protein that binds to actin filaments and runs along their length, covering the myosin-binding sites on actin when the muscle is relaxed.

### Conclusion
After analyzing all the options, we find that the **incorrect statement** is **Option 1**: "Each actin filament is made of 2G actin."

### Final Answer
The incorrect statement is Option 1.

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