Final answer:
The greatest fraction of a cell's mass is water; however, focusing on dry weight, it is comprised of macromolecules containing carbon, which represents approximately 12 percent of the cell's total dry weight.
Step-by-step explanation:
The greatest fraction of a cell's mass is made up of water, but if we exclude water and focus on the dry weight, it's primarily composed of biological macromolecules. These macromolecules are organic, which means they contain carbon as a core element, alongside hydrogen, oxygen, nitrogen, and additional minor elements. Carbon represents approximately 12 percent of the total dry weight of a typical cell and is a fundamental component of all macromolecules, including proteins, nucleic acids, carbohydrates, and lipids.
It is essential to recognize that while carbon is a significant part of the cell's composition, it does not account for 50% of the cell's total composition. The statement that carbon or nitrogen accounts for 50% is incorrect. Instead, oxygen also plays a critical role, being a major component in all macromolecules and constituting a considerable percentage of a cell's mass. Combined, these elements make up the bulk of a cell's dry mass. In cellular experiments, researchers often explore the synthesis of proteins using components such as mRNA and ribosomes, as it helps to understand the fundamental processes that utilize these elements.
While macromolecules and their constituent elements form the dry mass of cells, the nucleus is identified as the most prominent organelle within eukaryotic cells, serving as the control center responsible for storing genetic instructions. Some specialized cells have unique features, such as muscle cells being multinucleated or red blood cells lacking a nucleus to maximize space for hemoglobin, essential for oxygen transport.