Structure, Classification, Examples, and FAQs of Amoeba
All living beings on the earth are made up of structures called cells. Down at the microscopic level, this is the very basis of life. Every organism, including humans, begin their lives as a single cell and then branch into millions of these cells. Some organisms, however, remain single-celled for all their lives. They are microscopic organisms and they require only one cell to survive. One of the most common of this variety is an amoeba.
What is Amoeba?
Amoeba is a unicellular organism that can only be viewed under a microscope. It is a simple eukaryotic organism that moves around through Pseudopodia (cytoplasm pushing the cell membrane); the word pseudopodia means ‘false feet’.
They are commonly found on freshwater surfaces such as ponds and rivers. The ability to change its body shape as required is the key feature to amoebae (plural). The scientific name of amoeba is “Amoeba proteus”, also termed as the genus name. Amoeboid cells are generally found within animal species, some forms of algae, and even in fungi. Asexual reproduction is the typical nature of amoebic cells and the cells multiply through a biological process called binary fission (or multiple fission).
What Does the Structure Of Amoeba Look Like?
Accounting to the amoeba’s characteristics, its cytoplasm along with cellular contents enclose within a cell membrane. The DNA is bundled into the main cellular compartment, called the nucleus, and is covered by the plasmalemma. The nucleus comprises other several membrane-bound genetic organelles that help in protein transportation and produce energy.
To name a few:
Contractile vacuoles (osmoregulation subcellular structures)
Golgi apparatus (a folded membrane with vesicles)
Fat globules (the hydrophobic intracellular pieces)Food vacuoles (a storage unit for every food)
Water globules (small, colourless, spherical vacuole water elements)
Mitochondria (the powerhouse of a cell)Speaking of its cytoplasmic entity, an amoeba has 2 layers namely the inner endoplasm (granulated) and outer ectoplasm (non-granulated).
The entire body of an amoeba is transparent and looks similar to gelatin. When it comes to the food consumption process of an amoeba, a prey is usually ingested either through pinocytosis or phagocytosis. Adding to this, an amoeba can turn itself into a microbial cyst, when its food and living food conditions are abnormal. Bacteria, plant cells, metazoa, algae, protozoa are some of the common examples of what an amoeba eats. Yet, it does not have a well-defined mouth or anus for secretion or excretion. Since every amoeboid cell is a pseudopod, it does not have a definite shape. However, the size of an amoeba cell is around 250 and 750 microns. There are even amoebae that are visible to a human’s naked eyes. Moreover, A. Proteus is the biggest known cell in the unicellular kingdom of organisms.
Amoeba Classification
The classification of amoeboid cells has a few critics since it possesses only a true nucleus and is neither an animal nor a plant. To maintain consistency, ameboid cells are classified commonly under the Protista Kingdom. Following below is the scientific representation of the amoeba classification:
Domain: Eukaryota
Kingdom: Amoebozoa
Phylum: Tubulinea
Order: Tubulinida
Family: Amoebidae
Genus: Amoeba
Species: Proteus, animalcule, dubia, animalcule, etc.
Current research studies focus on classifying amoeboid cells using their subunit ribosomal RNA (SSU rRNA) genes. ‘Sarcodina’ is the single-most acceptable taxonomic group for the classification of amoeba cells. This is classified based on certain observable characteristics and after studying its morphology. Note that this classification is not based on any evolutionary relationship and hence it is not to be considered as a family tree.
Some Examples Of Amoeba:
Many varieties of amoeba can be found in the surroundings, in places that are damp and watery. They are mostly seen in wet soil and freshwater environments. The most common example of free-living amoeba is the Amoeba proteus. This can grow up to a size of 2 mm, and unlike other varieties, this is not pathogenic and can not cause any diseases in humans or animals.
Can Amoeba be Dangerous?
Some other varieties of amoeba are opportunistic pathogens. This means that they can be free-living, however, they prefer to infect and live inside a host and derive nutrition from them. These parasites can cause problems like amoebic dysentery and amoebiasis in human beings. These pathogens can be ingested with food and/or water and they can form a cyst-like structure inside the host’s body. These can be significantly harmful since sometimes the pathogens can invade the bloodstream and reach other vital organs.
Another kind of dangerous amoeba lives in freshwater, Naegleria fowleri. It can also be free-living but can invade the bodies of hosts and derive nutrition from them. The severity of this infection lies in the fact that this pathogen can enter the nasal mucosa and travel upwards towards the brain. It feeds on specific brain tissues such as neurons. This can be fatal for human beings if not detected in a timely manner, since it may lead to primary amoebic meningoencephalitis.
FAQs on Amoeba
1. At what temperature can amoeba die?
Mostly, amoeba does not bother people and can be free living. In some other cases, however, these can infect human beings and cause a host of problems. As we have discussed, the brain-eating amoeba can even cause permanent brain damage and death. Therefore it is important to know how long they can survive in the body. The temperature inside the body is optimum for these to thrive since they are mostly found in damp and wet environments. Most amoebae do not react to high temperatures, but they can be killed in very low temperatures. Freeing can be even useful in killing their offspring.
2. How do amoeba feed?
As can be understood from the structure of amoeba, they do not have hands and legs that can facilitate specific motor abilities. They move around with their whole body and this is also how they feed. They stretch out a pseudopod and engulf their food from all sides, and then digest it. A pseudopod is an arm-like extension that stretches from the body of an amoeba. Amoeba can eat a number of things, ranging from algae, other small plant matter, small bacteria, other protozoans, dead animal matter, fungi, and so on. Pathogenic amoeba can feed on the brains and organs of living beings as well.
3. How can water be filtered to remove amoeba?
One of the main sources of amoeba infection is through drinking dirty water. It is not entirely possible to find water free from all microorganisms, since amoeba is found pretty much in all wet environments. However, making sure that the water we drink is purified and made fit for consumption is very important. Some varieties of amoeba can infect a person even when they do not drink it. In these cases, it is always advised to use chlorine treatments on water or use distilled water. For drinking purposes, only purified water should be consumed.
4. Is it possible for the amoeba to become larger in size?
While most amoebae are not visible to the naked eye, it is absolutely possible for them to get bigger in size to the point where they become noticeable. Some amoeba can grow up to 2 millimeters in length as well. The size of the amoeba depends on the kind of food they feed on. They get bigger and bigger as they keep feeding. Even when it turns big after engulfing food, it may not be particularly visible to the human eye, since it is colourless and has a very transparent body.
5. Is amoeba useful for the environment?
Amoeba forms a very important part of the ecosystem of the soil and the water they inhabit. They can regulate the number of algae that grows in these places by routinely feeding on them. They also feed on bacteria which may be harmful to the soil or which may consume too much of the algae for the system to be in balance. When amoeba are broken down, the soil derives nutrients from them. Research has been going on to see if amoeba can be employed in medical sciences to feed on harmful bacteria that affect human beings.
6. Is Amoeba Unicellular?
Yes. Amoeba is a single-celled eukaryotic organism that does not have a definite shape due to its pseudopodia.
7. Who Discovered Amoeba?
August Von Rosenhof, who was a German naturalist, miniature painter, and entomologist discovered amoeba in 1755. He was a significant contribution to the field of modern entomology.
8. Why is Amoeba Called Immortal?
2 days is the general lifespan for an amoeba cell. Yet the daughter cells produced through binary /multiple fission are a replica of the parent cell. This is 1 reason why the amoeba is immortal in technical aspects.
9. At What Level of Organization is an Amoeba?
Ameboid cells will not be considered for a single taxonomic group. But they occur in multiple lineages of eukaryotic organisms. Examples include bacteria, fungi, protozoa, etc.
10. Can Amoeba Regenerate if Cut?
Yes. Amoeboid cells have the capacity of regeneration after cutting into pieces. Each piece cut will regenerate and form a new amoeba. But if a fragment does not have its nuclear components, then it cannot regenerate.
