Yes, a single cell is alive.
What Makes a Cell Alive?
A single cell, the fundamental unit of life, exhibits all characteristics of a living organism. Key features include:
- Metabolism: Cells take in nutrients from their environment, converting them into energy and building blocks for growth and repair. This is explicitly stated in the provided reference: "If you take a human cell and apply either of the definitions above, it is alive. A cell is capable of autonomous reproduction, and metabolizes substances harvested from its environment."
- Reproduction: Cells are capable of making copies of themselves through cell division, ensuring the continuation of life. This is also supported by the reference: "A cell is capable of autonomous reproduction..."
- Growth: Cells increase in size and complexity as they accumulate resources and synthesize new components.
- Response to stimuli: Cells react to changes in their surroundings, adapting to maintain homeostasis (internal balance).
Several sources highlight the ability to work with single cells while maintaining their viability. For instance, Live-seq, discussed in a Nature article, is a method for single-cell transcriptome profiling that keeps cells alive during RNA extraction. (https://www.nature.com/articles/s41586-022-05046-9). Other techniques, like those mentioned in Nature Biotechnology (https://www.nature.com/articles/s41587-022-01515-8) and the NCBI Bookshelf article on isolating and growing cells in culture (https://www.ncbi.nlm.nih.gov/books/NBK26851/), further demonstrate the ability to handle single cells while preserving their life functions.
While many cells function as part of a larger multicellular organism, their individual life processes are undeniable. The fact that cells can be isolated and cultured in vitro (outside of an organism) further substantiates their independent status as living entities.
Examples of Single-Celled Organisms
- Bacteria
- Archaea
- Protozoa
- Yeast
