Amoeba: Diagram and Characteristics (original) (raw)

Last Updated : 23 Jul, 2025

**Amoeba or Amoeboid is **a transparent single-celled eukaryotic microorganism with a jelly-like cytoplasm structure. It **can change its structure and **depends on division-based reproduction. It can **adapt to ever-changing surroundings to survive. Amoeba is irregular in shape with two protoplasmic layers, a single nucleus, and a contractile vacuole. They are generally found in the **seas, rivers, lakes, or dump soil and can **cause so many diseases for humans, **like Amebiasis. In this article, we will discuss the **Amoeba, Parts of amoeba, Biological Classification of Amoeba, and its Characteristics and Structure in detail.

Table of Content

• What is Amoeba?
• Diagram of Amoeba
• Biological Classification of Amoeba
• Structure of Amoeba
• Characteristics of Amoeba
• Parts of Amoeba
• Interesting Facts of Amoeba
• Amoeba Related Disease - Amebiasis

What is Amoeba?

**In 1755, German naturalist August Johann Rösel von Rosenhof first discovered and illustrated the specimen of amoeba. The name came from the Greek term ****"amoibe"** which **means "the change". Amoeba is a colourless uni-nuclear or single-cell organism that can change its shape with the pseudopodia. Pseudopodia are generally an arm-like temporary structure of cytoplasm that consists of a cell membrane. The lifespan of an amoeba is just two days. Amoeba reproduce its traits through binary fission which is an asexual reproduction. It is a fact amoeba are immortal as they depend for reproduction on binary fission.

Also Read: Difference Between Unicellular And Multicellular Organisms

Diagram of Amoeba

Amoeba is a transparent single-celled eukaryotic microorganism. It is a jelly-like cytoplasm structure. It can change its structure and depends on division-based reproduction. The Diagram of Amoeba is as follows:

Biological Classification of Amoeba

Amoeba belongs to the **Protista kingdom and **Amoebidae family. Here is the biological classification of amoeba.

Structure of Amoeba

Amoeba **is the simplest form of life that have jelly-like structure. It is very small in size and only visible under the microscope. The structure of the Amoeba is as follows:

• The size of an amoeba ranges from 0.05 mm to 0.1 mm.
• Amoeba has a flexible and elastic cell membrane that surrounds the entire cell.
• The cell membrane is semi-permeable, allowing the passage of substances in and out of the cell.
• They have a finger-like projection, known as pseudopods (pseudopodia).
• Amoeba possesses a single, centrally located nucleus within its cell which contains DNA.
• In pseudopods, the cytoplasm pushes the plasma membrane in and out which creates the finger-like structure pseudopods.
• Contractile vacuoles controlls the water balance in an amoeba cell.
• The plasma membrane consists of protein and lipid molecules. It is a thin and two-layer structure.
• It also contains other cellular organelles like vacuoles, mitochondria, Golgi apparatus, and fat globules, etc.
• The process of how amoeba consumes food is known as pinocytosis.

Characteristics of Amoeba

Amoeba is commonly found in freshwater environments such as ponds, streams, and lakes. It thrives in habitats with abundant organic material for nutrition. Here are some major Characteristics of Amoeba as mentioned below:

• The cell of amoeba is flexible and lacks a fixed shape.
• Pseudopodia is considered as the false feet of amoeba. It helps in the movement of the organism.
• Ectoplasm is a clear and transparent structure that is the inside part of the plasma membrane.
• The central endoplasm is granular.
• Amoeba do not have any mouth or anus.
• They do not contain any cell walls.
• DNA is present into the nucleus.
• By forming a vacuole with pseudopodia, it takes its food into its body.
• Enzymes digest the food particles and collect the nutrients from them.
• Contractile vacuoles regulate the water level in the body and maintain the osmotic pressure.
• Encystation is a phenomenon by which an amoeba can survive in an extreme environment.
• In extreme environmental conditions, the organism loses all the water from the body to gain a circular structure.

Parts of Amoeba

Amoeba, being a unicellular organism, does not have distinct anatomical parts like multicellular organisms. However, it possesses various structures and regions that contribute to its cellular functions. An amoeba has four major parts including Pseudopodia, Plasmalemma, Cytoplasm, and Endoplasmic Organelles.

Pseudopodia

Key features of psuedopodia are:

• It is a blunt-ended finger-like extension that helps to move amoeba.
• Pseudopodia is also known as the lobopodia.
• These are made by both ectoplasm and endoplasm.
• Liquified and forward-flowing cytoplasm is responsible for forming these cylindrical structures.

Plasmalemma

Key features of plasmalemma are:

• It is a thin and invisible cell membrane.
• The thickness of this elastic membrane varies between 0.00025 mm to 2 microns.
• It is a double-layer lipid made of protein molecules.
• Mucoproteins are generally attached to the outer surface of the plasmalemma.
• It is a self-healing membrane which can regenerate when it is broken.
• Plasmalemma exchange the water molecules and with this amoeba performs its respiration.
• It also helps amoeba to form pseudopodia and capture foods.

Cytoplasm

Key features of cytoplasm are:

• Plasmalemma is surrounded by cytoplasm which contains different organelles.
• Cytoplasam is divided into two parts as outer ectoplasm and an inner endoplasm.
• The ectoplasm is a thin and clear hyaline layer located under the plasmalemma.
• Endoplasam is a granular fluid which is surrounded by ectoplasam. It contains several organelles.

Endoplasmic Organelles

Key features of endoplasmic organelles are:

• Endoplasm contains a single conspicuous nucleus that contains over 500 small spherical chromosomes.
• Water Globules are small and colorless. They maintain the balance of the body.
• Amoeba also have mitochondria which look like rods and dots.
• There are fat and carbohydrate particles present in the endoplasm. These are the stored foods present in the body of amoeba.

Vacuoles

Vacuoles are the endoplasmic organelles which plays a major role in a amoeba's body.

• **A contractile vacuole is clear and round in structure. It is filled with watery fluid. They help in the process of osmoregulation, respiration, and excretion.
• **Food Vacuoles are different in size and scattered in the endoplasm. They help to digest the food particles with digestive enzymes.

Interesting Facts of Amoeba

Let us see some major facts about the amoeba as mentioned below:

• Amoeba is an unicellular organisms known for their structure changing abilities.
• They do not have fixed body structure.
• Reproduce asexually through binary fission.
• It can form cysts in unfavorable conditions to raise new traits.
• Contractile vacuole regulates water content and adapt to changing environments.

Amoeba-related diseases primarily involve the protozoan parasite Entamoeba histolytica, which is different from the harmless free-living amoebae. The main disease associated with Entamoeba histolytica is amebiasis. The key characteristics are:

• Entamoeba histolytica causes an intestine infection. It is majorly known as Amebiasis.
• Poor sanitary conditions can lead to a great risk for amebiasis. The symptoms are loose stool, abdominal cramping, and stomach pain.
• Amoebiasis is transmitted through the fecal-oral route.
• Sometimes they can be transmitted indirectly through the dirty hands.
• Infection can be treated with a 10-day course of metronidazole tablets.
• Prevent amoebiasis: Wash and peel fruits and vegetables, avoid unpasteurized dairy, ice cubes, and street vendor food; drink bottled or properly boiled water.

**Also Read:

• Protozoans
• Nutrition in Amoeba with Diagram and its Process