Difference between prokaryotes and Eukaryotes

//Difference between prokaryotes and Eukaryotes

Even though at very elemental level, all of the cells require the same functions to survive, yet the significant differences between prokaryotes and eukaryotes includes structural differences and in replication process.

 

Most noteworthy is lack of nucleus in the bacteria and archaean – the two types of prokaryotic cells.

Prokaryotes :

 

  • Are almost similar
  • Do not contain any membrane enclosed organelles
  • Replicates via process of binary fission
  • Lacks histones in their DNA’s

 

In addition, presence of the rods, spheres or spiral aid in the identification of three main types of prokaryotic bacteria. Eukaryotic cells also contain other organelles besides the nucleus. An organelle is a structure within cytoplasm that performs a specific job in a cell. Organelles known as mitochondria, for example, provides energy to the cell, and organelles known as vacuoles store substances in a cell. These organelles allows eukaryotic cells to carry out more functions than prokaryotic cells. Ribosomes, where proteins are manufactured, are only organelles in the prokaryotic cells.

 

Based on the property, prokaryotes and eukaryotes are differentiated below.
SIZE:

  • Prokaryotes are very small, some are larger than 50 micron.
  • Eukaryotes are large range between 10 to 100 microns but some are larger than 1 mm.

Characteristics:

  • Prokaryotes: All are microbes. Unicellular or colonial. Nucleoid is not membrane bound. More important, a circular, easily identifiable dark object in center of the cell, nucleus is the first and most important characteristic of a eukaryotic cell.
  • Eukaryotes: Most are large organisms only few are microbes and possess a membrane bound nucleus.

Cell division:

  • Prokaryotes: No mitosis or meiosis. Mainly through binary fission.
  • Eukaryotes: Cell division through mitosis and meiosis.

Sexual system:

  • Prokaryotes: Its absent in most forms if present transfer of genetic material occurs through unidirectional approach.
  • Eukaryotes: Present in most forms, equal male and female participation by means of fertilization.

Development:

  • Prokaryotes: There is no multi cellular development from diploid zygotes and no extensive tissue differentiation.
  • Eukaryotes: Haploid are produced through meiosis and diploid from zygotes.Extensive tissue differentiation occurs in multi cellular organism.

Flagella type:

  • Prokaryotes: Simple flagella made of one fibril.
  • Eukaryotes: Flagella are of 9+2 type.

Cell wall:

  • Prokaryotes: Made up of peptidoglycan (mucopeptide).Cellulose is absent.
  • Eukaryotes: Cell wall is made of cellulose in plants and chitin in fungi.

Organelles:

  • Prokaryotes: Membrane bound organelles such as endoplasmic reticulum, golgi complex, mitochondria, chloroplast and vacuoles are absent.
  • Eukaryotes: Here all the above membrane bound organelles are present.

Ribosomes:

  • Both cells have large no. of ribosomes, but ribosomes of the eukaryotic cells are larger in no. and more complex than ribosomes of the prokaryotic cells. Ribosomes are made out of a special class of RNA molecules, known as ribosomal RNA or rRNA and a specific collection of different proteins. A eukaryotic ribosome is typically composed of five kinds of rRNA and about eighty kinds of different proteins. Prokaryotic ribosomes are composed of only three kinds of rRNA and about some fifty kinds of other proteins. Lets have some quantitative analysis on this as follows :

 

  • Prokaryotes: Ribosomes are smaller ,made up of 70s units(here “s” refers to svedberg unit,it is the sedimentation co-efficient of a particle at ultracentrifuge)
  • Eukaryotes: Ribosomes are larger and made up of 80s units.

DNA:

  • Prokaryotes: DNA is not found in well organized chromosomes. It floats freely around the cell. We can say that prokaryotic DNA is naked, means it has no histones associated with it and is not formed into chromosomes.
  • Eukaryotes: It is found in well organized chromosome. The DNA of eukaryotes is held within its nucleus and associated with histones (or proteins)

 

 

By | 2015-08-24T14:24:07+00:00 December 26th, 2012|Cell Biology|0 Comments

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