why do plant cells have cell walls
Plant and animal cells have several differences and similarities. For example, animal cells do not have a cell wall or chloroplasts but plant cells do. Animal cells are round and irregular in shape while plant cells have fixed, rectangular shapes. Plant and animal cells are both, so they have several features in common, such as the presence of a cell membrane, and cell organelles, like the nucleus, mitochondria and endoplasmic reticulum. Plants are ; they produce energy from sunlight through the process of, for which they use cell organelles called. Animal cells do not have chloroplasts. In animal cells, energy is produced from food (
) via the process of.
Cellular respiration occurs in mitochondria on animal cells, which are structurally somewhat analogous to chloroplasts, and also perform the function of producing energy. However, plant cells also contain mitochondria. Another difference between plant cells and animal cells is that animal cells are round whereas plant cells are rectangular. , all animal cells have whereas only some lower plant forms have centrioles in their cells. Plant cells have a rigid cell wall that surrounds the cell membrane. Animal cells do not have a cell wall. When looking under a microscope, the cell wall is an easy way to distinguish plant cells.
Animal cells have one or more small vacuoles whereas plant cells have one large central that can take up to 90% of cell volume. In plant cells, the function of vacuoles is to store water and maintain turgidity of the cell. Vacuoles in animal cells store water, ions and waste. For a more in-depth look at the differences between plant and animal cell organelles,. What is a Cell Membrane? All living things are made from cells. Plant cells are somewhat unique because unlike animal cells, plant cells contain both a cell wall and cell membrane. Animal cells only have the cell membrane.
The cell membrane is a semi-permeable covering surrounding the outside of the cell. Plant cell membranes are found on the outside of the cell cytoplasm and just inside the cell wall. For a better idea, have a look at the structure of the plant cell. The plant cell membrane is shaded yellow. So what do plant cell membranes actually do? Well, our initial definition said that cell membranes are semi-permeable, and that they surround the cell. This information hints at two primary functions of plant cell membranes. First, the membrane retains the cell's cytoplasm and interior parts, and second, it allows specific substances to pass through it, while prohibiting others from doing so.
The first of these functions is fairly obvious. Just like a water balloon holds water inside, the cell membrane holds all cellular components inside. No big surprise there. The membrane, along with the cell wall beside it, keeps the cell together. So rather than focus on the obvious function, let's look at the second job: controlling entry and exit from the cell. By controlling what gets into and out of the cell, the membrane is functioning as a regulatory structure. An example of something the plant cell membrane regulates is the release of enzymes. Enzymes are molecules that speed up chemical reactions.
One such enzyme belongs to the pitcher plant. These plants are carnivorous and eat insects. The plant cell membrane inside pitcher plants will release enzymes to aid in digestion. Inversely, plant cell membranes can also prevent material from entering the cell. For example, harmful bacteria cannot simply invade the plant cell's interior because the membrane will not allow it to cross. To understand how plant cell membranes control the materials entering and exiting the cell, we must first understand what the membrane is made of. For that, please refer to the diagram of the cell membrane.
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