All forms of life are built from the cell. Both plants and animals are composed of eukaryotic cells, meaning their internal components are organized into specialized, membrane-bound organelles. These shared features include a true nucleus that houses genetic material and mitochondria, which generate the cell’s energy. Despite this common organizational foundation, the distinct lifestyles of plants and animals have driven several profound differences at the cellular level, primarily in structures responsible for support, energy acquisition, and cellular division.
Structural Support: The Cell Wall vs. the Cell Membrane
The most immediate difference is the presence of a rigid cell wall surrounding plant cells. This outer layer is primarily composed of cellulose, a tough polysaccharide that provides mechanical strength and protection. This durable casing helps plant cells maintain a fixed, often geometric shape and prevents the cell from rupturing if it absorbs too much water.
Animal cells lack a cell wall, relying instead on the flexible plasma membrane as their outermost boundary. This dynamic lipid bilayer allows animal cells to adopt a variety of shapes and enables movement necessary for functions like ingesting material. Animal cells maintain their internal structure primarily through an internal network of protein filaments known as the cytoskeleton.
Energy Production: Chloroplasts and Photosynthesis
A second major difference is how each cell type obtains energy. Plant cells contain chloroplasts, which are the sites of photosynthesis. These structures contain the pigment chlorophyll, which captures light energy from the sun. Chloroplasts convert light energy, carbon dioxide, and water into chemical energy (glucose), making plants autotrophs.
Animal cells lack chloroplasts and cannot perform photosynthesis, classifying them as heterotrophs. They must ingest organic molecules by consuming other organisms to acquire energy. The presence of chloroplasts grants plant cells a direct, self-sufficient energy source that is metabolically unavailable to animal cells.
Storage and Turgor Pressure: The Central Vacuole
The management of water, nutrients, and waste differs due to the presence of the central vacuole in plant cells. This single, large, membrane-bound sac can occupy up to 90% of the cell’s total volume. Its size allows it to store water, maintaining internal hydrostatic pressure against the cell wall, known as turgor pressure.
Turgor pressure gives non-woody plants their characteristic rigidity and upright posture. The central vacuole also serves as a reservoir for ions, nutrients, and waste products. Animal cells either contain no vacuoles or possess several small, temporary vesicles. These smaller structures primarily function in transport or temporary storage, but they do not contribute to the overall structural integrity of the cell through turgor pressure.
Cellular Organization: Centrioles and Cytokinesis
The final distinction is found in the machinery responsible for cell division. Animal cells contain a pair of cylindrical organelles called centrioles, positioned within the centrosome. Centrioles help organize the microtubules that form the mitotic spindle, which separates the duplicated chromosomes during division.
Plant cells, particularly those of higher plants, do not possess centrioles but divide successfully using a different type of microtubule-organizing center. The final stage of division, called cytokinesis, also differs due to structural differences. Animal cells divide by forming a cleavage furrow, where an actin ring pinches the flexible membrane inward. Plant cells, constrained by the rigid cell wall, instead build a cell plate in the center that expands outward until it fuses with the existing cell walls, creating a new partition.