The cell is the basic unit shared by all living beings, from the smallest unicellular microorganisms to the most complex multicellular organisms (Zahonero Bermejo, 2017). However, despite this common unit, cells are not identical to each other. Among living organisms, animals and plants are characterized by having more complex cellular interactions, which allow them to form specialized tissues and organs with these microscopic bodies. In correspondence with Zahonero Bermejo (2017), it is essential to highlight that, although they share the same cellular basis, plants and animals exhibit notable differences in their cellular structure.
Differences Between Animal and Plant Cells
Animal and plant cells share the characteristic of being eukaryotic cells, which means their genetic material is contained within a nucleus separated from the rest of the cell and they have membrane-bound organelles that perform vital functions for these microscopic elements (Zahonero Bermejo, 2017). Despite this similarity, there are specific differences that allow distinguishing between plant and animal cells. According to Zahonero Bermejo (2017), some of these differences are so notable that in histology (the study of tissues), one can determine whether a tissue sample comes from a plant or an animal just by observing it under the microscope.
Nutrition
Plants carry out autotrophic nutrition through photosynthesis (Amador Sánchez, 2021). Thus, they can manufacture all the organic matter they need to live from inorganic compounds such as carbon dioxide. This means that plants make their own nutrients with the help of their chloroplasts. Animals, on the other hand, have heterotrophic nutrition. Since they cannot perform photosynthesis, they have to obtain organic matter from another living being (either a plant or an animal). Once the necessary nutrients enter the cell, mitochondria use them to obtain energy. Due to their synthesis capability, plants are the first link in the food chain and store 80% of terrestrial organic carbon. In contrast, according to Amador Sánchez (2021), animals occupy higher positions in the ecosystems they inhabit, and a large part of their energy dissipates between each trophic level.
External Structures
The plasma membrane, a double lipid layer that separates the internal from the external environment, is common to both animal and plant cells (Bertran Prieto, 2021). However, their composition differs in a key aspect: animal cells have cholesterol (a lipid that reduces membrane fluidity), while plant cells do not (Bertran Prieto, 2021). The animal cell is only bounded by the plasma membrane, but the plant cell has an additional barrier: the cell wall (Amador Sánchez, 2021). This rigid structure provides protection and supports tissues, as the wall acts as the foundation for cellular organization (Zahonero Bermejo, 2017). Animal tissues also consist of cell networks, but without a cell wall. Instead, they have the extracellular matrix, which is not seen in plant tissues. According to Zahonero Bermejo (2017), this space is formed by structural proteins such as collagen, which provide a means to connect cells and shape tissues.
Despite these differences, the cell wall and extracellular matrix share a common function: providing structural support (Zahonero Bermejo, 2017). The absence of a cell wall in animal cells allows them to adopt significantly greater morphological diversity compared to plant cells, which, due to the presence of the cell wall, maintain a more constant shape, typically rectangular prisms with little variation (Bertran Prieto, 2021). Corresponding to Bertran Prieto (2021), this contrast is evident when considering the morphological difference between a neuron and a muscle cell.
Cell Division
The process of cell division, whether mitosis or meiosis, is another source of differentiation between animal and plant cells (Zahonero Bermejo, 2017). When the cell divides into two, the mechanism employed varies according to the cell type. While in animal cells, it occurs through the constriction of the cell membrane, in plant cells, it occurs through the formation of a septum. According to Zahonero Bermejo (2017), this septum will become part of the future cell wall that separates the two sister cells.
Organelles
The main characteristic of plants lies in their ability to obtain energy from sunlight, i.e., perform photosynthesis (Zahonero Bermejo, 2017). This ability is attributed to the presence of an exclusive organelle in plant cells, known as the chloroplast. This organelle is responsible for carrying out the process of photosynthesis using the pigment chlorophyll, responsible for the green color in plant leaves and some algae (Zahonero Bermejo, 2017). According to Bertran Prieto (2021), animal cells do not perform photosynthesis, so they evidently lack these chloroplasts.
Both animal and plant cells contain vacuoles, cellular organelles that are closed compartments (or connected to the plasma membrane) with different fluids or solid compounds inside them (Amador Sánchez, 2021). These organelles function to store substances, but this varies depending on the organism to which the cell belongs. The size and function of vacuoles are another difference between animal and plant cells. Animal vacuoles are small and store waste products, while the plant vacuole is large and occupies a significant portion of the cytoplasm. In fact, according to Amador Sánchez (2021), the vacuole of a plant cell can occupy up to 30% of its volume.
Cilia are short appendages shaped like "eyelashes" composed of microtubules and axonemes (Amador Sánchez, 2021). These appendages have a diameter of approximately 0.25 micrometers and a length of 15 micrometers and are located on the surface of many animal and protozoan cells. Some cilia facilitate cell movement, while others move fluids. Primary ciliated cells are found in all animal tissues (except blood) and their main function is sensory perception. In contrast, according to Amador Sánchez (2021), plant cells do not have cilia in any case, probably due to the limitations imposed by the cell wall.
Mitochondria are the most famous organelles in the field of cells, as cellular respiration takes place in them (Amador Sánchez, 2021). These organelles provide most of the metabolic energy to the cell, producing ATP from metabolic substrates (glucose, fatty acids, and amino acids). The quantity of mitochondria is another difference between animal and plant cells. Animal cells have more mitochondria than plant cells, as human cells can have from 2 to 2500, depending on the tissue type and energy demand. On the other hand, leaf cells of a plant have 300 to 450 mitochondria. According to Amador Sánchez (2021), this is because plant cells have plastids and a giant vacuole, which reduces the space available for mitochondria.
Cytoskeleton
The cytoskeleton is an essential component of cells, as it gives them shape, facilitates the transport of organelles and vesicles through the cytosol, and participates in cell division (Zahonero Bermejo, 2017). However, this component presents some differences between animal and plant cells (Zahonero Bermejo, 2017). For example, in animal cells, the cytoskeleton includes an organelle called the centriole, which consists of microtubules that have two main functions: helping in the separation of daughter cells during cell division and serving as a pathway for the movement of other organelles (Zahonero Bermejo, 2017; Bertran Prieto, 2021). In contrast, according to Zahonero Bermejo (2017), centrioles have not been detected in plant cells, nor have cells with the ability to move, due to the presence of the cell wall.
References
Amador Sánchez, S. A. (2021, septiembre 28). Diferencias Entre Célula Animal y Célula Vegetal. Muy Salud. https://muysalud.com/bioquimica/diferencias-celula-animal-celula-vegetal/
Bertran Prieto, P. (2021, diciembre 2). Las 8 Diferencias Entre Célula Animal y Célula Vegetal (Explicadas). Medicoplus.com. https://medicoplus.com/ciencia/diferencias-celula-animal-celula-vegetal
Zahonero Bermejo, M. (2017, abril 2). Las 4 Diferencias Entre la Célula Animal y la Vegetal. Psicología y Mente. https://psicologiaymente.com/salud/diferencias-celula-animal-vegetal
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