Animal cells do not have cell walls because they do not need them. Cell walls, which are found in plant cells, maintain cell shape, almost as if each cell has its own exoskeleton. This rigidity allows plants to stand upright without the need for bones or musculature.Know More
It is generally an advantage for plants to stand upright and grow as tall as possible. Plants need sunlight, so growing taller than neighboring plants make it more likely that the plant will survive and successfully reproduce. For animals, height may be an advantage sometimes as well, but most animals have skeletons and musculature. They do not need the rigid network that cell walls provide to stand upright.
Furthermore, most animals can move, and this capability is an enormous advantage when it comes to feeding, finding a mate and escaping from predators. If animals had cell walls in the same way plants do, they would be incapable of movement. Animals that do not move, such as coral and sea sponges, tend to grow in communal groups and develop structures that are very plant-like.
Animals and plants evolved differently, each according to different sets of needs. For animals, mobility was a greater advantage. Having cells without the rigidity of cell walls meant greater flexibility and motility.Learn more about Biology
Biosynthetic capacity, the nature of cell division machinery and the fact that cells grouped together form various organs and structures are factors thought to influence and limit cell size in animals. The full extent of the processes that regulate cell size are not fully understood.Full Answer >
Cell walls are located around the plasma membranes of certain types of cells. Cell membranes protect the cell, but cell walls have many extra functions, including providing an extra layer of protection and giving cells a more rigid structure.Full Answer >
A haploid cell is one that contains only a single set of chromosomes. In humans, a haploid cell consists of 23 chromosomes. Both sperm and egg cells are haploid.Full Answer >
Unlike bacteria, archaea are able to live in extreme environments, some produce methane, their plasmid membranes are unique compared to other lifeforms and their cell walls lack peptidoglycan, which is present in bacteria cell walls. There are three main forms of archaea: thermophiles, halophiles and methanogens.Full Answer >