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What is Amoeba? Definition, Structure, Classification, Nutrition

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Amoeba are single-celled creatures capable of simple division-based reproduction. Amoeba, the most basic form of life can be found in seas, rivers, lakes, ponds, and damp soil. The Greek term ‘amoibe’, which signifies change, is where the word amoeba comes from. Amoebas must adapt to their ever-changing surroundings in order to survive. We will look into the structure, classification, nutrition, and characteristics of amoeba in this article.

What is Amoeba?

Amoeba is a single-cell organism, which can change shape accordingly with the help of pseudopodia. They can normally be found in water bodies. In some cases, they succeed to enter into the human body and causing disease. The 18th century offers one of the earliest records describing amoebas. Comprehensive pictures of the species were produced in 1755 by a German scientist by the name of August Johann Rösel von Rosenhof.

The term amoeba relates to a fundamental eukaryotic organism that moves in a unique crawling manner. However, a closer look at the hereditary makeup of the various amoeba reveals that these life forms are not truly closely related to one another. There are a few exceptions to the general rule that most of these organelles are typical of all eukaryotic cells. According to a recent study published in The Journal of Biological Chemistry, parasitic one-celled creatures like Entamoeba histolytica, which produce amoebic loose stools in humans, lack the Golgi apparatus, the organelle responsible for modifying and transporting proteins.

Structure of Amoeba

An amoeba is a single-celled microorganism that lacks both shape and color. Its structure resembles the structure of jelly, and it could take on another shape. Its body is shaped asymmetrically. It can only be seen under a microscope due to its extremely small size. The dimensions of it run across the range from 1/20 mm to 0.1 mm. Pseudopodia, which aid in mobility and food intake, are finger-like projections that may be seen if you look closely at the structure of an amoeba. The cytoplasm extends into the pseudopods. Fat globules, the Golgi apparatus, and other cell organelles are also found in amoebas.

Amoeba Structure

Parts of Amoeba

The following components make up an amoeba’s cell:

Cell Membrane

The amoeba is protected by this layer of protein and fat. It permits the movement of materials into and out of the cell.

Nucleus

The amoeba’s brain is located in the nucleus. It controls the entire functioning of the amoeba and contains the genetic material for its growth.

Vacuoles

Air sacs known as vacuoles can be found in the cytoplasm of amoebae. Amoeba has three different types of vacuoles, each of which performs a different task.

  • Contractile Vacuole: Osmoregulation is the process by which contractile vacuoles control the osmotic pressure by expelling water from the cell.
  • Food Vacuole: Food vacuoles come in various diameters and are non-contractile (fixed form). These have food that the amoeba has consumed.
  • Water Globules: Water globules are tiny, amorphous, noncontractile spheres that are filled with water.

Cytoplasm

The cytoplasm of an amoeba is a gel-like substance that houses all of its organelles.

Pseudopods

The amoeba can move around and grasp food particles with the assistance of these finger-like extensions.

Characteristics of Amoeba

Amoeba possesses the following characteristics:

  1. The life of a common amoeba is 2 days, but since it divides by binary fission, the resultant daughter cells are equivalent to its parent cell, so in fact, the amoeba can be named immortal.
  2. Under unfavorable conditions, the amoeba can basically change itself into a shielded ball, called a microbial cyst. Under favorable conditions, it can again transform into its trophozoite stage, and again start feeding.
  3. Development and locomotion happen using pseudopodia, where the cytoplasm pushes the plasma layer outward or inward, making gruff, finger-like projections.
  4. Amoeba eats food either through the course of phagocytosis or pinocytosis.
  5. Amoeba reproduces via binary fission which is a mode of asexual reproduction.
  6. The plasma layer is an extremely thin, twofold layered membrane made out of protein and lipid particles.
  7. Amoeba likewise contains other cell organelles like a contractile vacuole, mitochondria, Golgi, and fat globules.

Amoeba Classification

Classification of Amoeba is as follows:

Domain

Eukaryota

Kingdom

Amoebozoa

Phylum

Tubulinea

Order

Tubulinida

Family

Amoebidae

Genus

Amoeba

Species

Animalcule

Mode of Nutrition 

A process known as phagocytosis provides nutrition to amoebas. The method through which the organism absorbs the food is called phagocytosis. Holozoic nutrition is the term for the amoeba’s mode of nutrition. It comprises the ingestion of food material as well as its digestion and egestion.

Ingestion

The most common way of bringing food into the body either by gulping or retaining it is known as the technique of Ingestion. Amoeba overflows out the pseudopodia to surround the food and inundates it framing a food vacuole. This interaction is known as phagocytosis.

Phagocytosis

Digestion

The most common way of breaking insoluble and huge food atoms into dissolvable and minute particles is known as the course of Digestion. Absorption in amoeba happens intracellularly, inside the cell. The food is put away in a food vacuole or stomach vacuole, which is comprised of the cell membrane and a little measure of cytoplasm. Cytoplasmic movements transport the vacuoles more profoundly into the cells. They, later on, join with lysosomes, which contain catalysts. in this area, amylase and proteinase are two catalysts that can be found. In amoeba, the food vacuoles are put further into the cell, and with the help of stomach-related proteins, the enormous insoluble particles are broken down into simple compounds.

Absorption

The supplements from the processed food material are consumed by the cell’s cytoplasm by keeping behind the undigested particles. This is known as absorption. The overabundance of food is put away as a type of glycogen and lipids.

Assimilation

The most common way of acquiring energy from the retained food complex is known as the method of Assimilation. In amoeba, assimilated food particles are used for creating the energy expected to hold different life processes inside the cell.

Egestion

The course of discharge of undigested and waste food material is called Egestion. In amoeba, this cycle is directed by bursting the cell division to take out the undigested food material from its body. Exocytosis is the course of egestion. Undigested materials are moved to the rear of the single adaptable cell and removed as food pellets through a transient opening delivered anytime on the plasmalemma as the amoeba goes ahead.

FAQs on Amoeba

Q: How does an amoeba obtain its food?

Answer:

Amoeba obtains their food with the help of pseudopodia and the process is known as phagocytosis.

Q: Who discovered amoeba?

Answer:

Scientist August Von Rosenhof discovered amoeba in 1755.

Q: Is amoeba unicellular or multicellular?

Answer:

Amoeba is a unicellular organisms i.e. they are single-celled eukaryotes without having a defined shape.

Q: Why amoeba is called immortal?

Answer: 

Amoeba reproduces by binary fission and produces 2 daughter cells. Daughter cells are clones of the parent cell, that’s why amoeba is called immortal.

Q: At what temperature do amoeba cells die?

Answer:

Amoeba cells can not survive in dry and high temperatures. 



Last Updated : 16 Aug, 2023
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