The 8 differences between animal cell and plant cell (explained)
According to the latest taxonomic classification, the world of living beings is divided into a total of seven kingdoms. But it is no secret that, of these, the two best known are, without a doubt, the animal and the vegetable. Animals and plants are two totally different kingdoms of living things And, at least from our human point of view, they are, due to their relevance in our lives, the most important.
Animals are (we are) multicellular organisms as a result of the aggregation of animal cells that specialize to form more or less complex organs and tissues that give rise to a heterotrophic being (consumes organic matter) that reproduces sexually and has systems mobility, presenting some kind of symmetry in his body. They appeared 750 million years ago and a total of 953,000 different species have been identified.
Plants, for their part, are also multicellular organisms but the result of the aggregation of plant cells that have the almost exclusive property (shared with algae and cyanobacteria) of carrying out photosynthesis, a process that allows obtaining energy to synthesize their own organic matter from starting from the light. Plants lack locomotion systems and can reproduce sexually or asexually. They appeared 541 million years ago and a total of 215,000 species have been identified.
And among these definitions, there are two key concepts: animal cell and plant cell. And it is that all the differences that we can imagine between an animal and a plant are reduced to this. To the morphological and physiological differences between the animal and plant cells, which are the fundamental unit of both types of living beings. Therefore, in today's article and, as always, from the hand of the most prestigious scientific publications, we are going to analyze the most important differences between the animal cell and the plant cell in the form of key points.
What is an animal cell? And a plant cell?
Before going into depth and presenting the main differences between the animal and plant cells in the form of key points, it is interesting (and also very important) that we put ourselves in context and define both cells individually. Let's see, then, what exactly is an animal cell and a plant cell.
Animal cell: what is it?
An animal cell is a type of eukaryotic cell that constitutes the simplest biological unit of animal tissues.. And it is that all animals are the result of the union of animal cells that, differing morphologically and physiologically in various cell types, give rise to all the organs and tissues of the animal kingdom.
Every animal cell is essentially made up of three elements: plasma membrane (the cell envelope that separates the internal environment from the external environment), cytoplasm (the internal environment where the different cell organelles are found) and the cell nucleus (a structure encompassed by a plasma membrane inside which is the genetic material).
Animal cells have a metabolism based on heterotrophyIn other words, these cells need to consume organic matter as a source of carbon and energy. When we eat (we always feed on other living beings), we do it to give these cells the matter they need to regenerate and to have energy in the form of ATP.
Thus, digestion takes place at the intracellular level. These animal cells perform an endocytosis of the nutrients, making them enter through the plasma membrane and degrading them into simple biomolecules that act as intermediates in metabolism. In order to do this, they lack a cell wall (a structure that is present in plants), something that, in turn, allows their great morphological diversity.
And is that animal cells can take a variety of forms: neurons, muscle cells, epithelial cells, kidney cells, sperm, eggs, red blood cells, lymphocytes, adipocytes ... And this morphological and physiological diversity explains that, without taking bacteria into account, the animal is the kingdom with the largest number of different species.
The origin of the animal cell dates back to about 750-700 million years in the past, appearing as an evolution of protozoa. And practically all animals (with the exception of the 28 species of loricefers whose cells do not have mitochondria) are aerobic, that is, their cells necessarily consume oxygen (and expel carbon dioxide as waste), a compound that mitochondria (a type cell organelles) need to generate energy for these animal cells to stay alive and functional.
Plant cell: what is it?
A plant cell is a type of eukaryotic cell that constitutes the simplest biological unit of plant tissues.. They are, with the exception of algae (which do not belong to the plant kingdom, but to the chromist kingdom) and cyanobacteria (which belong to the bacterial kingdom), the only cells specialized in carrying out photosynthesis.
Thus, plant cells do not have a metabolism based on heterotrophy, but on autotrophy (the organism is capable of creating its own food) and, more specifically, on photoautotrophy. Plant cells are capable of transforming light energy from sunlight into chemical energy.
Plant cells base their metabolism on photosynthesis. And this chemical energy is "stored" so that, after fixing (which is a concept that we can understand as "capturing") the atmospheric carbon dioxide, they can join the carbon atoms to increasingly complex molecules at the biochemical level until get organic matter and give oxygen as a waste product.
At a structural level, to the three elements that we have seen in the animal cell, we should add a fourth: the cell wall. This structure, present in plant, fungal and bacterial cells, is an extra envelope located above the plasma membrane with the function of stiffening the cell and protecting it from the external environment. This wall, in plants, is basically made up of cellulose.
Anyway, this presence of the cell wall greatly limits the morphological diversity that these plant cells can acquire. Hence, most plant cells are rectangular. This, in turn, limits the variety of tissues that plants present and explains, in part, why the diversity of plant species is lower than that of animals: 215,000 and 953,000, respectively.
In addition, other important characteristics is the presence, in the cytoplasm, of both chloroplasts (exclusive organelles of algae plants, inside which are chlorophyll pigments that, in addition to being responsible for the green color of plants, allow reactions photosynthetic) as a large vacuole, a large structure that the plant cell uses to store water and nutrients. All plants on Earth are made up of these plant cells.
How are animal and plant cells different?
After analyzing both cells in depth, it has surely become more than clear that animal and plant cells are like night and day. They evolutionarily separated hundreds of millions of years ago, so their morphological and physiological properties are very different. And although we could make an almost infinite list of differences, we have prepared a selection of the main differences between animal cells and plant cells so that you can stay, seeing it in the form of key points, with the most relevant information.
1. Animal cells are heterotrophic; vegetables, photoautotrophs
Animal cells are based on heterotrophy, that is, they need to consume organic matter and digest nutrients intracellularly to obtain the necessary carbon and energy. Instead, plant cells are photoautotrophic, that is, they do not need to consume organic matter, because through photosynthesis, a process to obtain chemical energy from sunlight, they can synthesize it.
2. Plant cells have a cell wall; the animals, no
At the structural level, plant cells have a cell wall, an extra envelope around the membrane that provides rigidity and greater protection to the cell. Animal cells, on the other hand, do not have it. Its membrane is "naked", something that also explains the next point that we are going to see.
3. The morphological diversity of animal cells is greater
By not having a cell wall, animal cells can adopt a much greater morphological diversity. You just have to think about how different a neuron is from a muscle cell. In contrast, plant cells are much more limited in shape due to the cell wall, always being rectangular prisms, with little variety.
4. The animal plasma membrane contains cholesterol; the vegetable, no
Both the animal and plant cells have a plasma membrane, which consists of a double lipid layer that separates the internal environment from the external one. In any case, its composition is different in one key aspect: the animal cell has cholesterol (a lipid reduces the fluidity of the membrane) and the plant cell does not.
5. The animal cell stores energy in glycogen; the vegetable, in starch
Both the animal and plant cells store their energy through biomolecules. But the way they do it is different. In the animal cell, the energy reserve is in the form of glycogen; while in the vegetable it occurs in the form of starch. Both are polysaccharides but their chemical structure is different.
6. The plant cell has chloroplasts; the animal, no
Chloroplasts are organelles containing chlorophyll, the pigment that makes photosynthesis reactions possible. Animal cells never photosynthesize, so they obviously lack these chloroplasts. On the other hand, all plant cells contain them, which also explains why, because of these chlorophyll pigments, plants are green.
7. The animal cell has centrioles; the vegetable, no
The centrioles are microtubules that, in addition to maintaining the structure of the cell, are responsible for intervening in cell division (they are the cylindrical tubes that serve as support so that, when the cell divides, it separates properly) and to be the "highway" where the other organelles travel. And an important difference between these cells is that while the animal has them, the plant lacks them.
8. The plant cell has a single large vacuole; the animal, several of small
Vacuoles are cellular organelles that consist of a kind of vesicles with the function of storing nutrients and water. In the case of the plant cell, there are a single large vacuole that occupies practically the entire cytoplasm, as it is essential to maintain the water balance and to give turgor on the cell wall. On the other hand, in the animal cell there are several but they are small and do not represent such an important part of the cytoplasm.