What are mesosomes? Give their functions.

Explanation

### Step-by-Step Solution:

1. **Definition of Mesosomes**:
Mesosomes are defined as the folded invaginations of the plasma membrane found in gram-positive bacteria. They appear as structures that extend into the cytoplasm from the cell membrane.

2. **Structure of Mesosomes**:
In the context of a bacterial cell, mesosomes can be visualized as folds or projections of the plasma membrane. They are typically located near the cell wall and contribute to the overall surface area of the cell.

...