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Differences between eukaryotic and prokaryotic cells
Cell size
Eukaryotic cells are ordinarily larger (10 – 100um) than prokaryotic cells (1 – 10um).
Cell arrangement:
Eukaryotes are often multicellular whereas prokaryotes are unicellular. There are
however some exceptions –unicellular eukaryotes include amoebas, paramecium,
yeast.
True membrane-bound nucleus:
Eukaryotic cells have a true nucleus bound by a double membrane. It contains the
DNA-related functions of the large cell in a smaller enclosure to ensure close
proximity of materials and increased efficiency for cellular communication and
functions.
In contrast, the smaller prokaryotic cells have no nucleus. The materials are already
fairly close to each other and there is only a "nucleoid" which is the central open
region of the cell where the DNA is located.
DNA structure
Eukaryotic DNA is linear and complexed with packaging proteins called "histones,"
before organization into a number of chromosomes
Prokaryotic DNA is circular and is neither associated with histones nor organized into
chromosomes. A prokaryotic cell is simpler and requires far fewer genes to function
than the eukaryotic cell. Therefore, it contains only one circular DNA molecule and
various smaller DNA circlets (plasmids).
Membrane-bound organelles
Eukaryotic cells contain many membrane-enclosed, large, complex organelles in the
cytoplasm whereas prokaryotic cells do not contain these membrane-bound
organelles.
This is a key difference because it allows a high level of intracellular division of labor
and contributes to the greater complexity characteristic of eukaryotic cells.
Due to the larger size of the eukaryotic cells, confining certain cellular process to a
smaller area also increases the efficiency of functions by improving communication
and movement within the cell.
Only eukaryotes possess a membrane-bound nucleus and membrane-bound organelles
such as the mitochondria, golgi apparatus, lysosomes, peroxisomes and ER.
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Ribosome size
Both eukaryotic and prokaryotic cells contain many ribosomes; however the
ribosomes of the eukaryotic cells are larger than prokaryotic ribosomes
Eukaryotic ribosomes also show more complexity than prokaryotic – they are
constructed of five kinds of ribosomal RNA and about eighty kinds of proteins. In
contrast, prokaryotic ribosomes are composed of only three kinds of rRNA and about
fifty kinds of protein.
Cytoskeleton
This is a multicomponent system in eukaryotes composed of microtubules, actin
filaments and intermediate filaments. It is required for maintaining cell shape,
providing internal organization and mechanical support. It is also paramount in
movement and cell division.
Cell division
This occurs by mitosis for eukaryotic cells and binary fission for prokaryotic cells.
Eukaryotic cells undergo mitosis then cytokinesis. This involves numerous stages -
the nuclear membrane disintegrates then the chromosomes are sorted and separated to
ensure that each daughter cell receives two sets (a diploid number) of chromosomes.
Following this, the cytoplasm divides to form two genetically identical daughter cells
i.e. cytokinesis.
In contrast, prokaryotes undergo a simpler process of binary fission. This is faster
than mitosis and involves DNA (nucleoid) replication, chromosomal segregation, and
ultimately cell separation into two daughter cells genetically identical to the parent
cell. Unlike mitosis, this process does not involve the nuclear envelope and
centromere and spindle formation.