PLANT VS ANIMAL CELLS

July 20, 2019Neural Academy

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Plants and animal cells share many similarities since they are both eukaryotes, which means that they have a membrane-bound nucleus. Plant cells are often larger than animal cells. Well… except eggs… the largest animal cell is an unfertilized ostrich egg, which weighs around 1.5 kg!!! So let’s discuss similarities! Both animal and plant cells have membrane-bound organelles. They also both have cytoplasm, a cell membrane, a nucleus, mitochondria, rough and smooth endoplasmic reticulum, a Golgi apparatus, and peroxisomes.
The nucleus is where the genetic information of the cell is housed. The cytoplasm is not to be confused with the cytosol. The cytoplasm is the entirety of the cell contained by the cell membrane. The cytosol on the other hand is the part of the cytoplasm not taken up by organelles. The cell membrane is an important semi-permeable division between the cell and its surroundings. It allows the cell to control its own biochemistry by only letting certain substances through it.
Mitochondria are the powerhouses of the cell. They are specialized to perform aerobic respiration, converting glucose to ATP, which is the energy currency of the cell that is used to perform functions necessary for life. Both rough and smooth endoplasmic reticulum help with the production and storage of proteins. The rough endoplasmic reticulum is covered in ribosomes, which translate RNA into protein. The smooth endoplasmic reticulum makes lipids. The golgi apparatus modifies proteins. Peroxisomes metabolize waste.
Now let’s get to the differences between plant and animal cells. One major difference is that plant cells have a rigid cell wall around their plasma membrane. It is composed of cellulose, providing additional stability and protection. As a result, plant cells have fixed, angular shapes, while animal cells are mostly round and irregular.
Another important difference between animals and plants is how they obtain their energy. Plants are autotrophs, which means that they produce their own food. Meanwhile, animals are heterotrophs, meaning that they must ingest their food. Plants produce sugars through photosynthesis, and then break down the sugar to produce energy. Animals consume other organisms such as plants to obtain sugar, which they then also break down to produce energy. Again, the sugar is broken down in mitochondria.
Plants are autotrophs thanks to special organelles called chloroplasts, which are full of chlorophyll, a green pigment that captures light energy to drive the reactions in photosynthesis. Photosynthesis is the process by which plants use the sun’s energy to make sugar. Once the sugar is made, it gets broken down in mitochondria.
Another important difference between plant and animal cells is in their vacuoles. Vacuoles in plant cells can occupy up to 90% of cell’s volume and have a single membrane. One of their roles is simply to fill up space but they can also have digestive functions similar to lysosomes. Vacuoles have enzymes that perform many functions and can store nutrients or provide space to degrade waste substances. Animal cells can also have vacuoles, but they are MUCH smaller than the large central vacuole in plant cells and there are multiple of them and they don’t take up 90% of the space.
Plant and animal cells both also have cytoskeletons, which feature microtubules, intermediate filaments, and microfilaments. However, these structures are arranged differently in plant and animal cells. Centrioles are present in all animal cells but only in lower plant forms such as Chlamydomonas. Centrioles are microtubule organizing centers, which are structures from which microtubules emerge. Plants don’t have centrioles, but instead have many small nucleation sites.
In plants – only gametes can have flagella – such as the sperm of bryophytes. Some animal cells also have flagella. In humans, sperm are the only cells with flagella, however, many animal cells have cilia, unlike most plant cells. For example, we have cilia in our respiratory system which help remove debris and mucus, in the female reproductive system to help sperm move towards the egg, and elsewhere.
Animal cells have clearly-defined lysosomes. It’s still debated whether some plant cells have them though. Lysosomes are membrane-bound spherical vesicles containing hydrolytic enzymes that can break down biomolecules. They are involved in cell processes like secretion, plasma membrane repair, cell signaling, and energy metabolism.
Plant cells also have plasmodesmata, which are channels that connect two plant cells. An analogous structure in animal cells is the gap junction, which connects the cytoplasm of two adjacent cells.