What differentiates animal and plant cells?

Animal cells and plant cells share much of the basic structure since they are both eukaryotic cells. Both types have similar cytoplasmic membranes and various types of cell organelles, internal structures that have their own lipid membrane and are related to very specific cellular functions.

One of the most characteristic organelles present in all eukaryotic cells is the Cell nucleus, an organelle that separates DNA from the cytoplasm and other cellular structures. Other common organelles in plant and animal cells are, for example, mitochondria, endoplasmic reticulum, Golgi apparatus or peroxisomes.

In addition to these similarities, plant and animal cells have very important differences, highlighting the plant cell wall and unique organelles of only one of two cell types, for example, the vacuoles, lysosomes and centrioles of animal cells, or the chloroplasts of plant cells. .

most important differences

size and shape

Although there are animal and plant cells of widely varying sizes, animal cells are generally smaller. A typical animal cell is between 10 and 30 micrometers in size, while a plant cell can range between 10 and 100 micrometers.

The same happens with the shape, although there are animal and plant cells of very different shapes, animal cells tend to have a rounded or irregular shape, while plant cells tend to have a rectangular or geometric shape. This is due to the presence of the plant cell wall, a rigid cellulose structure that determines the cell’s shape.

cell wall

All plant cells have a cellulose cell wall that surrounds the entire cell in a relatively rigid structure, including the cytoplasmic membrane. Cellulose cell wall is a very important feature and plant cell differentiation. There are other organisms that have cell walls, but only plants have cellulose. Animal cells do not have any kind of cell wall.

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plasmodesmus

Plasmodesmata are pores present in the cell wall, therefore not present in animal cells, which communicate the cytoplasm of contiguous cells allowing the direct circulation of molecules and communication signals between them.

organelles

Animal cells and plant cells have many organelles in common, including the nucleus, mitochondria, endoplasmic reticulum and Golgi apparatus, all of which are also present in other types of eukaryotic cells, for example, in fungi.

Perhaps the most characteristic and distinctive organelles of plant cells are the plastid organelles where the most important substances for the plant cell are synthesized and which they share with many types of algae:

Chloroplasts: contains several pigments capable of absorbing energy from sunlight, mainly chlorophyll, and photosynthesis in them. Chromoplasts: synthesize and store many plant pigments, especially yellow, red and orange from the carotenoid group (carotenes and xanthophylls). Leucoplasts: These are colorless or “white” plastids that appear in areas of plants not exposed to light or photosynthetic. They are usually storage vacuoles with reserve substances. Depending on the type of substance stored, they are called amyloplasts (starch), oleoplasts (lipids) or proteoplasts (proteins).

glyoxysomes are other organelles present only in plants; They help to degrade lipids during germination. Another difference is the storage vacuoles. In animal cells, they are usually small and numerous. In plant cells, on the other hand, it is common to have a large central vacuole that can occupy almost the entire cytoplasm.

Among the many functions of this large vacuole is the degradation of macromolecules. In animal cells, this function is performed by lysosomes, a type of organelle that rarely appears in plant cells.

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centrioles and cytokinesis

Animal cells have structures called centrioles that are not present in plant cells and that are essential for numerous cellular functions, including cell division by mitosis or meiosis.

A centriole is composed of 9 triplets of microtubules similar to those of the cytoskeleton. Two perpendicular centrioles form the diplosome, a non-membranous organelle typical of animal cells. A particular type of diplosome, called a centrosome, guides the division of a cell into two daughter cells (cytokinesis).

At the beginning of prophase (the first phase of cell division), each centriole on the centrosome migrates to an opposite pole of the cell, guiding protein aggregates with it to form the nucleus. mitotic spindle or achromatic spindle which are strands of microtubules that guide the movement of chromosomes to separate the cell in two.

Centrioles have many more functions. They are the anchoring axes of flagella and cilia and allow their movement. They also help maintain cell shape and interact strongly with the cytoskeleton to transport numerous substances and organelles through the cytoplasm.

Other differences

In animals, only stem cells have the ability to differentiate into other, more specialized cell types in the body. In contrast, almost all plant cells are pluripotent with the ability to differentiate. Plant cells can greatly increase in size by absorbing water. Animal cells cannot withstand this increase in size and pressure because they do not have a cell wall. Consequently, tissue growth in animals occurs primarily by cell division, whereas in plants there can be significant tissue growth without a proportional increase in cell number. Plant cells, lacking centrioles, also show no flagella or cilia, with the notable exception of some primitive plants with mobile gametes, such as liverworts; these plants have biflagellated male gametes that can travel short distances through water, although the structure is very different from true animal flagella. The main carbohydrate for energy stores in animal cells is glycogen in plant cells is starch. In plant cell membranes there is no cholesterol, while cholesterol is essential in the membrane of animal cells.

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