Final answer:
Water is the most abundant molecule in a bacterial cell, constituting up to 70% or more of the total weight of a cell, making it more abundant than proteins, lipids, and DNA.
Step-by-step explanation:
The most abundant molecule in a bacterial cell is water. While proteins are the most abundant organic molecules in living cells and form the structural basis of cell function, water constitutes the majority of a cell's total composition. In fact, water is essential and accounts for up to 70% or more of the total weight of a cell. Proteins, although highly abundant once water is removed, do not surpass the amount of water within the cell.
It's also worth noting that in any cell, not just bacterial cells, the cytoplasm is rich in dissolved solutes, and the cell relies on water to maintain these conditions. Additionally, water is a major component of the plasma membrane and is involved in many cellular processes, including the enzymatic functions that occur throughout the cell. Therefore, when considering the complete molecular makeup of a bacterial cell, water is the clear leader in abundance.