What is Prokaryote?

A single-celled organism without nucleus and other organelles with membranes. Prokaryotes are derived in the Greek pro (pro”pre” – meaning “before”) and the word karuon (karyon, meaning ‘nut’ or “kernel”). In the two-empire model that resulted in the works of Edouard Chatton, prokaryotes were classified as part of the Empire of Prokaryota. However, in the three-domain system that is based on molecular analysis, prokaryotes are divided into two domains: Bacteria (formerly Eubacteria) and Archaea (formerly Archaebacteria). Organisms with nuclei are put in the third domain, Eukaryota. When studying the evolutionary origins of life prokaryotes are believed to have ascended before Eukaryotes.

Apart from the lack of a nucleus prokaryotes are also devoid of mitochondria, or other organelles bound to membranes that define the eukaryotic cells, and it was thought previously that prokaryotic cells’ components inside the cytoplasm were not enclosed, with the exception of the cell’s outer membrane. However, microcompartments of bacterial origin that are believed to have been simple organelles encased in protein shells have been found as well as various other organelles found in prokaryotes. While they’re typically monocellular, some prokaryotes like cyanobacteria, can make large colonies. Some, like myxobacteria have multicellular stages during their life cycle. Prokaryotes reproduce without the fusion of gametes but horizontal gene transfer also occurs.

The study of molecular biology has provided insights into the development and interrelationships among the three realms of life. The separation between prokaryotes as well as Eukaryotes is due to their existence at two different levels of cell organization. the only cells that are eukaryotic have an enveloped nucleus which houses its chromosomal DNA as well as other distinct membrane-bound organelles, including mitochondria. Prokaryotes that are distinct from other types include methanogens and extremophiles. These are prevalent in extreme conditions.

What is Eukaryotes?

Eukaryotes are living creatures whose cells contain a nucleus that is enclosed in the nuclear envelope. Eukaryotes fall under the realm of Eukaryota or Eukarya Their name comes from the Greek Eukaryota (eu, “well” or “good”) and Karuon (karyon, “nut” or “kernel”). The domain Eukaryota is just one domain of life. archaea and bacteria (the prokaryotes) are the two other domains. Eukaryotes are generally thought of as having evolved in the Archaea or as a cousin of the more cultivated Asgard archaea. Eukaryotes are a tiny fraction of the total number of organisms, but due to their generally greater size and size global biomass is believed at around the prokaryotes. Eukaryotes began to appear around 2.1-1.7 billion years ago in their Proterozoic eon, probably being flagellated, phagotrophs.

Eukaryotic cells usually contain additional membrane-bound organelles, like mitochondria, Golgi apparatus, and chloroplasts are found in both algae and plants. Prokaryotic cells can include primitive organelles. Eukaryotes could be multicellular or unicellular, and contain a range of cell types that create different kinds of tissues. In contrast, prokaryotes are typically unicellular. Animals, plants, as well as mushrooms are the most commonly known Eukaryotes. Others are often referred to as protists.

Eukaryotes reproduce asexually via mitosis as well as sexually via meiosis as well as gamete fusion. Mitosis occurs when one cell divides and produces two identical genetically-identical cells. In meiosis, DNA replication occurs followed by two cycles of cell division to create four haploid cells. They are gametes, or sex cells. Each gamete has only 1 set of chromosomes each one a distinct mix of the respective parent chromosome pair, resulting from meiosis-induced genetic recombination.

Differences between Prokaryotes and Eukaryotes – Prokaryotes vs Eukaryotes

Character	Prokaryotes	Eukaryotes
Term Origin	Greek for “primitivenucleus”	Greekto refer to the “true nucleus”
Definition	Organisms that are made up of cell(s) without nuclei of cells or organelles with membranes.	Organisms composed of cells that have a membrane-bound nucleus , as well as organelles that are membrane-bound.
Major groups	Bacteria Archae Bacteria, Archae Bluegreen algae	Algae, fungiand protozoa Animals, plants, algae
Origin	The time was around 3.5 billion years ago.	Two billion years ago.
Size (approximate)	0.5-3.0 mm	>5 mm
Cell Type	Typically, they are unicellular (some cyanobacteria might be multicellular)	Usually, multicellular
Complexity	Simple	Complex organisation.
Nucleus Location	Cellulose-free, connected to mesosomes	Membrane bound structure
Nucleur membrane	No nuclear membrane.	The classic membrane is present.
Nucleolus	Absent	Present
Chromosome number	One	More than one
Shape of the Chromosome	Circular	Linear
Genes	Operans are groups of cells that are expressed in operons.	Individually
Genome	DNA haploid genome	DNA diploid genome
DNA base ratio (G+C %)	28-73	About 40
DNA wrapping on proteins	Multiple proteins work together in order to condense and fold prokaryotic DNA. The DNA that is folded is put into a variety of configurations that are supercoiled, and wrapped around tetramers from the Hu protein.	Eukaryotes are able to wrap their DNA around proteins known as histones.
Genome nature	Small and compact, but with a lot of repetitive DNA.	Large amounts in non-coding, repetitive DNA.
Organelles bound by membranes	Absent	Present
Ribosomes (sedimentation coefficient)	70S (50S + 30S).Smaller.	80S (60S + 40S). Larger.
The position of the Ribosome	In cytoplasm, free or boundto the cell’s to cell membrane	Attached to the rough endoplasmicreticulum
Mitochondria	Absent	Present
Golgi bodies	Absent	Present
Endoplasmic reticulum	Absent	Present
Mesosomes	Present. Functions as Golgi body and mitochondria, and aids in the separation of chromosomes during cell division.	Absent
Lysosomes	Absent	Present
Peroxisomes	Absent	Present
Chloroplasts	The chlorophyll is absent; it’s scattered throughout the cell cytoplasm	In the present (in plants)
Fimbriae	Prokaryotes could have pili as well as fimbriae (appendage that are present on several Gram-negative bacteria as well as certain Gram-positive bacteria).	Absent
Microtubules	Rare or absent	Present
Centrosome	Absent	The present is not evident, except for flowering plants.
Cytoskeleton	Could be absent	Present
Glycocalyx	Present	In a small fraction of
Cytoplasmic streaming	Absent	Present
Cytoplasmic membrane	Does not contain the sterols (except Mycoplasma)	Containing Sterols
Cell wall	Complex structure with proteins, lipids, as well as peptidoglycans	Cells of plants and Fungi. Other times, absent
Muramic acid	Present	Absent
Movement	Simple flagellum, if present	Complex flagellum, if present
Respiration	Through the cytoplasmic membrane	Via mitochondria
Site for energy production	The transport chain for electrons is located inside the cellmembrane	Within the membrane boundmitochondria
Metabolic rate	Greater due to a greater surface area to volume ratio	Comparatively slow
Reproduction	Asexual (binary fission)	Asexual and sexual division
Time to generate	Shorter	Comparatively more long
Genetic Recombination	Partial, unidirectional transfer	Meiosis and the fusion of gametes
Zygote	Merozygotic (partially diploid)	Diploid
ExtrachromosomalDNA	Plasmid	Inside themitochondria
DNA replication	It is found in the cells.	In the nucleus.
Translation and transcription	This occurs concurrently.	The transcription process occurs in the nucleus, and after that, translation takes place in the cells.