Glycogen differs from starch in

Options

A. kinds of bonds
B. kinds of molecules
C. being present in animals only.
D. structure of molecules

Answer

To answer the question "Glycogen differs from starch in," we need to consider several key aspects of these two polysaccharides.

### Step-by-Step Solution:

1. **Definition and Function**:
- Glycogen is a polysaccharide that serves as the primary storage form of glucose in animals. It is mainly found in the liver and muscles.
- Starch, on the other hand, is the storage form of glucose in plants, found in roots, tubers, and seeds.

2. **Monomeric Units**:
- Both glycogen and starch are composed of glucose monomers. However, the way these glucose units are arranged and bonded differs.

3. **Structure**:
- Glycogen has a highly branched structure. It consists of numerous glucose units connected by α(1→4) glycosidic bonds, with branches formed by α(1→6) glycosidic bonds occurring every 8 to 12 glucose units.
- Starch is made up of two components: amylose and amylopectin.
- Amylose is mostly linear, consisting of α(1→4) glycosidic bonds, and tends to coil into a helical structure.
- Amylopectin is branched like glycogen but has fewer branches than glycogen, with branches occurring every 24 to 30 glucose units.

4. **Solubility**:
- Glycogen is more soluble in water compared to starch due to its branched structure, which allows for more interaction with water molecules.
- Starch, particularly amylose, is less soluble because of its linear structure, which tends to form helical structures that are less accessible to water.

5. **Biological Role**:
- Glycogen is quickly mobilized to meet energy needs in animals, especially during intense physical activity.
- Starch serves as a long-term energy reserve in plants and is broken down more slowly.

### Conclusion:
In summary, glycogen differs from starch in terms of its source (animal vs. plant), structure (highly branched vs. less branched), solubility (more soluble vs. less soluble), and biological role (quick energy source vs. long-term energy storage).