What are some disadvantages for a cell in being small?

Answer 1

1. Materials can easily diffuse into (and out of) all parts of the cell.
2. The surface area to volume ratio is very high, meaning that there is plenty of plasma membrane to handle all of the cell's needs concerning materials entering and leaving the cell.
3. The DNA can easily be transcribed quickly enough to direct the formation of proteins the cell requires.

Edit: Sorry. I've listed advantages.

Disadvantages:
Limited interior space for organelles and molecules to use as raw materials in building RNA, proteins, ...