Main chain of glycogen and starch is helically coiled with each turn of helix having

Options

A. 10 - 14 glucose residues
B. 8 - 10 glucose residues
C. 6 glucose residues
D. 4 glucose residues.

Answer

To solve the question regarding the main chain of glycogen and starch and the number of glucose residues in each turn of the helix, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Glycogen and Starch Structure**:
- Glycogen and starch are polysaccharides made up of glucose units.
- Glycogen is primarily found in animal cells, while starch is found in plants.

2. **Linkages in Glycogen and Starch**:
- Glycogen is formed by glucose molecules linked together through α(1→4) glycosidic bonds in a linear fashion, with branching occurring at α(1→6) linkages.
- Starch consists of two components: amylose (linear chains of glucose with α(1→4) linkages) and amylopectin (branched chains with both α(1→4) and α(1→6) linkages).

3. **Helical Structure**:
- Both glycogen and amylopectin (a component of starch) have a helical structure due to the way glucose units are linked.
- The helical structure allows for efficient storage of glucose.

4. **Determining the Number of Glucose Residues per Turn**:
- Each turn of the helix in glycogen and amylopectin contains approximately 6 glucose residues.
- This is a characteristic feature of their structure, which contributes to their functionality as energy storage molecules.

5. **Conclusion**:
- Based on the structural analysis, the correct answer to the question is that each turn of the helix in glycogen and starch has **6 glucose residues**.

### Final Answer:
**Each turn of the helix in glycogen and starch has 6 glucose residues.**

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