Prokaryotes and Eukaryotes

The distinction between prokaryotes and eukaryotes is considered very important among organisms. Prokaryotes do not possess a membrane-bound nucleus while eukaryotes do. All cells are classified into prokaryotes or eukaryotes depending on either their nuclei and other organelles are bound to a membrane or not. There are many other differences between prokaryotes and eukaryotes which will be discussed in the next sections.

What are Prokaryotes?

The word Prokaryote is derived from two Greek words ‘pro’ meaning before and ‘karyon’ referring to the nucleus. These are the organisms whose cells have no true nucleus i.e., their genetic material is not membrane bound. Their cell walls are made of a different material than eukaryotes i.e., peptidoglycan. Prokaryotic cells are smaller than eukaryotic cells. Their DNA is in a circular shape or single loop which is stored in an area called nucleoid. As they have smaller cells, their surface area to volume ratio is high so are their metabolic rates. Examples of prokaryotes include bacteria and cyanobacteria.

What are Eukaryotes?

The word Eukaryote is derived from Greek ‘eu’ meaning true and ‘karyon’ meaning nucleus. They have a true nucleus. Eukaryotes are believed to be evolved from prokaryotes. They have larger cells than prokaryotes. Structural organization, as well as functional efficiency, is higher in eukaryotes. They possess a true membrane-bound nucleus. Their DNA is linear and packed with histone proteins to form chromatin. Examples of the eukaryotes include plants, animals, protists etc.

Difference between Cells of Prokaryotes and Eukaryotes

Prokaryotic cell Eukaryotic cell
No nuclear membrane or nucleoli True nucleus consisting of nuclear membrane and nucleoli
DNA circular and without proteins DNA linear associated with proteins to form chromatin
Genetic material not packed in chromosomes Gnetic material packed in chromosomes
Usually unicellular except a few cyanobacteria Usually multicellular
Cell wall if present; made up of peptidoglycan and chemically complex Cell wall if present; made up of Cellulose
No cytoskeleton Always have a cytoskeleton
Cell division by binary fission Cell division by mitosis or meiosis
Reproduction always asexual Asexual or sexual reproduction
Cell size 1-10 um Cell size 10-100 um
Lysosomes, peroxisomes, mitochondria, centrosome and Golgi apparatus absent. Lysosomes, peroxisomes, mitochondria, centrosome and Golgi apparatus Present.
Endocytosis and exocytosis absent. Endocytosis and exocytosis occur in eukaryotic cells.
Microtubules absent or rare. Microtubules absent.
Examples are bacteria and cyanobacteria Examples are plants and animals

 

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