Is Amoeba Prokaryotic or Eukaryotic? - detailed explanation

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Is amoeba prokaryotic or eukaryotic?

We know that Eukaryotic organisms evolved from prokaryotes as stated in
Endosymbiotic theory. So, We all have a question ‘ who are the first eukaryotes?’
Here, is the answer to your question. –   ‘Protozoans’.

Protozoans are the first single-celled eukaryotes to evolve from prokaryotes. In Greek,
‘photos’ means ‘first’ and ‘zone’ means ‘animals’.The study of protozoans is called ‘Protozoology’. They are categorized as Kingdom Protista in R.H.Whittakar’s Five Kingdom classification.

In this article, we are going to explain about – Is Amoeba prokaryotic or Eukaryotic?

Is Amoeba prokaryotic or eukaryotic?

Amoeba belongs to the eukaryotic cells. It has a well-defined nucleus and membrane-bound cell organelles which are the characteristics of the eukaryotic cell. Amoeba is present on the surface of ponds and lakes.

             Salient features

            Amoeba
                        Cell type                        Eukaryotic
               Level of organization                        Unicellular
                        Cell wall    Present in some (made up of cellulose), absent in others.
                  Mode of Nutrition   Autotrophic, Photosynthetic,                             Heterotrophic.
                          Motility           Motile or non-motile

Why Amoeba is Eukaryotic?

Amoeba is a simple Eukaryotic organism. Its genetic material is bound by a nuclear membrane and consist of membrane-bound organelles such as vacuoles, lysosomes and ribosomes, etc,. Except, Kingdom Monera, all others such as Protista, Fungi, Animalia and Plantae are eukaryotes.

Here, Let’s know about eukaryotic organisms in detail.

 What are eukaryotes?

Eukaryotes are organisms with a well-developed prominent nucleus, nuclear membranes, and organized membrane-bound organelles. In Greek, Eu’ means ‘true’ and karyon’ means nucleus’.

These Eukaryotic organisms have a prominent nucleus with tightly coiled chromosomes. These chromosomes contain DNA with histone proteins H2A, H2B, H3, and H4 attached to it. The chromatin organization is complex. It possesses all the membrane-bound organelles.

It contains 80S ribosomes (60S+40S). In most eukaryotes, cell division takes place through mitosis and meiosis. They may exist as both unicellular and multicellular.

 An Eukaryotic cell

The Endosymbiotic theory states that the Eukaryotes are descendants of Prokaryotes. The ancestors of eukaryotes engulfed a bacterium, and it continued inside the host cell. Thus, the cell organelles such as mitochondria and chloroplast were formed.

endosymbiotic theory

Some examples of eukaryotes

All the species under the Kingdom Fungi, Plantae, and Animalia are eukaryotes. Some of the species of Kingdom Protista are eukaryotes.

Why Amoeba is not Prokaryotic?

Amoeba is not a prokaryote, because it has a prominent nucleus surrounded by a nuclear membrane with membrane-bound organelles.

Prokaryotes do not have nuclei bound by a nuclear membrane and other organelles. And, their circular genetic material is set free in the cytoplasm without any membrane or envelope covering it.

To understand the answer, let us know about prokaryotic organisms in detail.

What are prokaryotes?

Prokaryotes are unicellular organisms that do not have a prominent nucleus without a nuclear membrane, and membrane-bound organelles. In Greek, Pro – primitive, karyo – nucleus. They are the first life forms in this world.

Usually, these prokaryotic organisms lack a nuclear membrane to their genetic material. They lack chromatin organization. They do not contain organelles such as mitochondria, endoplasmic reticulum, Golgi apparatus, etc,.

These organisms have 70S ribosomes(50S+30S). Their genetic material is circular, single-stranded, and does not contain histone proteins attached to its DNA. Hence, they are called Nucleiod or Genophore.

These Unicellular organisms have an extrachromosomal double-stranded structure called Plasmid. These are used in R-DNA technology. The cell division takes place by Binary fission.

prokaryotic cells

Some examples of prokaryotes

Species that belong to the kingdom Monera are prokaryotes. Bacteria and Archaebacteria prokaryotic organisms.

Difference between Eukaryotic and prokaryotic organisms:

In eukaryotes, the genetic material, DNA is present in the nucleus, mitochondria, and chloroplast. In prokaryotes the genetic material, DNA is present in circular chromosomes and plasmids.

difference between eukaryotic or prokaryotic cells

Eukaryotes and prokaryotes have cell walls, plasma membranes, DNA, ribosomes, and cytoplasm in common. The cell structure of both eukaryotes and prokaryotes are almost similar. Hence, Amoeba is eukaryotic and not prokaryotic.


What is Amoeba?

Amoeba is a unicellular, eukaryotic, motile, microscopic organism. It has a cell membrane, nucleus, food vacuoles and cytoplasm. It does not have a definite structure so, constantly changes its irregular shape. In the plural, it is called “Amoebae”.

Usually, protozoans have specialized organelles such as cilia, flagella, etc,. Likewise, Amoeba has also a specialized structure called Pseudopodia.

In Latin, Pseudopodia’ refers to ‘false feet’. It moves by using this Pseuodopodia. This is a finger-like projection that arises from the body for movement in search of food.

Eukaryotic Amoeba

The average lifespan of Amoeba is 2 days. It undergoes all life processes such as Respiration, Nutrition, Excretion and Reproduction for survival.

How does an Amoeba respire?

Respiration in the amoeba takes place through simple diffusion through the cell membrane. The atmospheric oxygen diffuses into the cell, and the carbon dioxide diffuses out into the atmosphere.
Amoeba

How does an Amoeba eats?

The mode of nutrition in amoeba is heterotrophic. It eats algae, bacteria, tiny particles and small dead plant particles as food. It intakes food by the process of Phagocytosis or endocytosis. Amoeba extends its pseudopodia to engulf the food material into the cell. Then, it forms a food vacuole and gets digested within the cell.

How does excretion occur in Amoeba?

Amoeba is an ammonotelic animal, it excretes ammonia as a nitrogenous waste product. There is no specialized organ for excretion. So, it excretes by diffusing the waste material to the surrounding water body. Sometimes, contractile vacuoles help in the process of excretion.

How does reproduction take place in Amoeba?

Amoeba reproduces asexually methods. It reproduces asexually by Binary fission, sporulation, multiple fission by encystment and plasmogamy.

Binary Fission

In Simple Binary fission, the parent divides into two equal halves to form two daughter individuals. The plane of division is hard to observe in Amoeba. The contractile vacuole ceases its function and the nuclear membrane disappears.

Then, the nucleus divides mitotically or mitotically and is followed by the division of the cytoplasm. Thus, the two daughter individuals identical to the parent are formed.

Sporulation

During unfavourable conditions, amoeba forms spores without encystment. The nucleus divides into spores or chromatin blocks. The nuclear membrane disappears and forms a spore case around the chromatin blocks.

When conditions become favourable, the cell disintegrates releasing the spores, and each hatches into a new individual.

Multiple fission by Encystment

During the period of unfavourable conditions such as food scarcity or increased or decreased temperature, Amoeba withdraws its pseudopodia and forms a three-layered, protective, chitinous cyst wall around it. This is called Encystment.

When conditions become favourable, the encysted amoeba reproduces by multiple fission forming daughter cells called pseudopodiospores or amoebae. These daughter cells feed and grow rapidly.

Plasmotomy

Some species of multinucleated amoeba reproduce by plasmogamy. The multinucleated parent cell divides into multinucleated daughter individuals with the division of nuclei. The nuclear division takes place later to maintain a normal number of nuclei.  Example: Opalina and Pelomyxa (giant amoeba).

These are the characteristic features of Amoeba. Thus Amoeba is said to be eukaryotic and not prokaryotic in nature.

Also Read:

FAQ

Is there any prokaryotic Amoeba?

No, Amoeba is a Eukaryote. It has a nucleus surrounded by a nuclear membrane and membrane-bound organelles in its cytoplasm.

Can we see amoeba through our naked eyes?

No, most of the amoebae are microscopic and cannot be seen through the naked eye. But, the so-called “giant amoebae” Pelomyxa palustris and Chaos carolinense, are visible as they are bigger.

Is Amoeba the first single-celled eukaryotic animal?

No, the first eukaryotic animal would have evolved before the evolution of amoeba. But considered as the ancestor of single-celled eukaryote.

Is amoeba immortal?

Yes, the amoeba multiplies by binary fission. Hence, the parent cell is transformed into a daughter cell. Due to this continuous process, it is considered immortal.

What happens if an amoeba doesn’t have pseudopodia?

It would die soon. Because the amoeba uses pseudopodia for locomotion and to engulf food.

Beneficial activities of Amoeba 

  • Amoeba helps to maintain a balanced ecosystem by feeding on bacteria and algae.
  • They also help the soil to prevent infection from harmful bacteria.

Harmful activities of Amoeba

  • There are many species of amoeba that are harmful to human life causing infections.
  • Entamoeba histolytica – causes amoebic dysentery in humans.
  • Naegleria fowleri – found in contaminated waterbodies are harmful to humans. These amoebae can damage brain tissues by eating them.

Summary:

  • Protista- Protozoans are eukaryotic, motile, unicellular and microscopic organisms.
  • Is Amoeba prokaryotic or Eukaryotic? – Amoeba is a eukaryotic microorganism, unicellular, with a prominent nucleus surrounded by a nuclear envelope and membrane-bound organelles.
  • Eukaryotes are organisms with a prominent nucleus and membrane-bound organelles.
  • Prokaryotes are organisms that lack a nuclear membrane, a prominent nucleus, and membrane-bound organelles.
  • Amoeba is a unicellular, eukaryotic, motile, irregular shaped microorganism. It has a specialised organelle called pseudopodia for locomotion.
  • It helps in maintaining ecological balance.
  • It causes amoebic colitis and amoebic dysentery to humans.
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