Eukaryote

The endomembrane system and its components
Simplified structure of a mitochondrion
Longitudinal section through the flagellum of Chlamydomonas reinhardtii
Structure of a typical animal cell
Structure of a typical plant cell
Fungal Hyphae cells: 1 – hyphal wall, 2 – septum, 3 – mitochondrion, 4 – vacuole, 5 – ergosterol crystal, 6 – ribosome, 7 – nucleus, 8 – endoplasmic reticulum, 9 – lipid body, 10 – plasma membrane, 11 – spitzenkörper, 12 – Golgi apparatus
This diagram illustrates the twofold cost of sex. If each individual were to contribute the same number of offspring (two), (a) the sexual population remains the same size each generation, where the (b) asexual population doubles in size each generation.
Phylogenetic and symbiogenetic tree of living organisms, showing a view of the origins of eukaryotes and prokaryotes
One hypothesis of eukaryotic relationships – the Opisthokonta group includes both animals (Metazoa) and fungi, plants (Plantae) are placed in Archaeplastida.
A pie chart of described eukaryote species (except for Excavata), together with a tree showing possible relationships between the groups
The three-domains tree and the Eocyte hypothesis
Phylogenetic tree showing a possible relationship between the eukaryotes and other forms of life; eukaryotes are colored red, archaea green and bacteria blue
Eocyte tree.
Diagram of the origin of life with the Eukaryotes appearing early, not derived from Prokaryotes, as proposed by Richard Egel in 2012. This view implies that the UCA was relatively large and complex.

Eukaryotes are organisms whose cells have a nucleus enclosed within a nuclear envelope.

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Diagram of a typical prokaryotic cell

Prokaryote

Single-celled organism that lacks a nucleus, and other membrane-bound organelles.

Single-celled organism that lacks a nucleus, and other membrane-bound organelles.

Diagram of a typical prokaryotic cell
Phylogenetic ring showing the diversity of prokaryotes, and symbiogenetic origins of eukaryotes
Phylogenetic and symbiogenetic tree of living organisms, showing the origins of eukaryotes and prokaryotes
Diagram of the origin of life with the Eukaryotes appearing early, not derived from Prokaryotes, as proposed by Richard Egel in 2012. This view, one of many on the relative positions of Prokaryotes and Eukaryotes, implies that the universal common ancestor was relatively large and complex.
Comparison of eukaryotes vs. prokaryotes
Phylogenetic tree showing the diversity of prokaryotes. 
This 2018 proposal shows eukaryotes emerging from the archaean Asgard group which represents a modern version of the eocyte hypothesis. Unlike earlier assumptions, the division between bacteria and the rest is the most important difference between organisms.

Organisms with nuclei are placed in a third domain, Eukaryota.

Plant

Green algae from Ernst Haeckel's Kunstformen der Natur, 1904.
A variaty of fungi species
Dicksonia antarctica, a species of tree fern
A petrified log in Petrified Forest National Park, Arizona
Range of pangaea glossopteris.
The leaf is usually the primary site of photosynthesis in plants.
There is no photosynthesis in deciduous leaves in autumn.
Plant cell structure
The Venus flytrap, a species of carnivorous plant.
Mechanical harvest of oats.
Melocactus plants being used as medicine.
Timber in storage for later processing at a sawmill
A rose espalier at Niedernhall in Germany.
Capitals of ancient Egyptian columns decorated to resemble papyrus plants. (at Luxor, Egypt)
Barbara McClintock (1902–1992) was a pioneering cytogeneticist who used maize (corn) to study the mechanism of inheritance of traits.
Musk Thistle are invasive species in texas.

Plants are predominantly photosynthetic eukaryotes of the kingdom Plantae.

The three-domains tree and the Eocyte hypothesis (Two domains tree), 2008.

Domain (biology)

Highest taxonomic rank of all organisms taken together.

Highest taxonomic rank of all organisms taken together.

The three-domains tree and the Eocyte hypothesis (Two domains tree), 2008.
Phylogenetic tree showing the relationship between the eukaryotes and other forms of life, 2006 Eukaryotes are colored red, archaea green, and bacteria blue.

According to the domain system, the tree of life consists of either three domains such as Archaea, Bacteria, and Eukarya or two domains consisting of Archaea and Bacteria, with eukaryotes included in Archaea.

Algae

False-color scanning electron micrograph of the unicellular coccolithophore Gephyrocapsa oceanica
title page of Gmelin's Historia Fucorum, dated 1768
The kelp forest exhibit at the Monterey Bay Aquarium: A three-dimensional, multicellular thallus
Rock lichens in Ireland
Floridian coral reef
Algae on coastal rocks at Shihtiping in Taiwan
Phytoplankton, Lake Chūzenji
Harvesting algae
Seaweed-fertilized gardens on Inisheer
Dulse, a type of edible seaweed
Algae bladder

Algae (singular alga ) is an informal term for a large and diverse group of photosynthetic eukaryotic organisms.

Onion (Allium cepa) root cells in different phases of the cell cycle (drawn by E. B. Wilson, 1900)

Cell (biology)

Basic structural and functional unit of life forms.

Basic structural and functional unit of life forms.

Onion (Allium cepa) root cells in different phases of the cell cycle (drawn by E. B. Wilson, 1900)
Structure of a typical prokaryotic cell
Structure of a typical animal cell
Structure of a typical plant cell
Detailed diagram of lipid bilayer of cell membrane
A fluorescent image of an endothelial cell. Nuclei are stained blue, mitochondria are stained red, and microfilaments are stained green.
Deoxyribonucleic acid (DNA)
Human cancer cells, specifically HeLa cells, with DNA stained blue. The central and rightmost cell are in interphase, so their DNA is diffuse and the entire nuclei are labelled. The cell on the left is going through mitosis and its chromosomes have condensed.
Diagram of the endomembrane system
Prokaryotes divide by binary fission, while eukaryotes divide by mitosis or meiosis.
An outline of the catabolism of proteins, carbohydrates and fats
An overview of protein synthesis.
Within the nucleus of the cell (light blue), genes (DNA, dark blue) are transcribed into RNA. This RNA is then subject to post-transcriptional modification and control, resulting in a mature mRNA (red) that is then transported out of the nucleus and into the cytoplasm (peach), where it undergoes translation into a protein. mRNA is translated by ribosomes (purple) that match the three-base codons of the mRNA to the three-base anti-codons of the appropriate tRNA. Newly synthesized proteins (black) are often further modified, such as by binding to an effector molecule (orange), to become fully active.
Staining of a Caenorhabditis elegans highlights the nuclei of its cells.
Stromatolites are left behind by cyanobacteria, also called blue-green algae. They are the oldest known fossils of life on Earth. This one-billion-year-old fossil is from Glacier National Park in the United States.
Robert Hooke's drawing of cells in cork, 1665

Cells are of two types: eukaryotic, which contain a nucleus, and prokaryotic cells, which do not have a nucleus, but a nucleoid region is still present.

thumb|Columbia, about 1,590 Mya

Proterozoic

Geological eon spanning the time interval from 2500 to 538.8million years ago.

Geological eon spanning the time interval from 2500 to 538.8million years ago.

thumb|Columbia, about 1,590 Mya
thumb|Rodinia, about 750 Mya
thumb|Pannotia, 545 Mya (disputed), centered on South Pole
thumb|Gondwana 420 Mya, centered on South Pole

The well-identified events of this eon were the transition to an oxygenated atmosphere during the Paleoproterozoic; the evolution of eukaryotes; several glaciations, which produced the hypothesized Snowball Earth during the Cryogenian Period in the late Neoproterozoic Era; and the Ediacaran Period (635 to 538.8 Ma) which is characterized by the evolution of abundant soft-bodied multicellular organisms and provides us with the first obvious fossil evidence of life on earth.

Modern stromatolites in Shark Bay, Western Australia. It can take a century for a stromatolite to grow 5 cm.

Unicellular organism

Organism that consists of a single cell, unlike a multicellular organism that consists of multiple cells.

Organism that consists of a single cell, unlike a multicellular organism that consists of multiple cells.

Modern stromatolites in Shark Bay, Western Australia. It can take a century for a stromatolite to grow 5 cm.
A bottom-dwelling community found deep in the European Arctic.
Paramecium tetraurelia, a ciliate, with oral groove visible
A scanning electron microscope image of a diatom
Transmission electron microscope image of budding Ogataea polymorpha

Organisms fall into two general categories: prokaryotic organisms and eukaryotic organisms.

The bacterium Escherichia coli (E. coli), is a single-celled prokaryote

Organism

Organism is any organic, living system that functions as an individual entity.

Organism is any organic, living system that functions as an individual entity.

The bacterium Escherichia coli (E. coli), is a single-celled prokaryote
An amoeba is a single-celled eukaryote
Polypore fungi and angiosperm trees are large multicellular eukaryotes.
Precambrian stromatolites in the Siyeh Formation, Glacier National Park. In 2002, a paper in the scientific journal Nature suggested that these 3.5 Gya (billion years old) geological formations contain fossilized cyanobacteria microbes. This suggests they are evidence of one of the earliest known life forms on Earth.
LUCA may have used the Wood–Ljungdahl or reductive acetyl–CoA pathway to fix carbon.

A unicellular organism may be either a prokaryote or a eukaryote.

(A) Electron micrograph of Halothiobacillus neapolitanus cells, arrows highlight carboxysomes. (B) Image of intact carboxysomes isolated from H. neapolitanus. Scale bars are 100 nm.

Organelle

Organelle is a specialized subunit, usually within a cell, that has a specific function.

Organelle is a specialized subunit, usually within a cell, that has a specific function.

(A) Electron micrograph of Halothiobacillus neapolitanus cells, arrows highlight carboxysomes. (B) Image of intact carboxysomes isolated from H. neapolitanus. Scale bars are 100 nm.
Structure of Candidatus Brocadia anammoxidans, showing an anammoxosome and intracytoplasmic membrane

There are many types of organelles, particularly in eukaryotic cells.

Animals are unique in having the ball of cells of the early embryo (1) develop into a hollow ball or blastula (2).

Animal

Animals are unique in having the ball of cells of the early embryo (1) develop into a hollow ball or blastula (2).
Sexual reproduction is nearly universal in animals, such as these dragonflies.
Predators, such as this ultramarine flycatcher (Ficedula superciliaris), feed on other animals.
Hydrothermal vent mussels and shrimps
The blue whale is the largest animal that has ever lived.
Dickinsonia costata from the Ediacaran biota (c. 635–542 MYA) is one of the earliest animal species known.
Anomalocaris canadensis is one of the many animal species that emerged in the Cambrian explosion, starting some 539 million years ago, and found in the fossil beds of the Burgess shale.
Non-bilaterians include sponges (centre) and corals (background).
Idealised bilaterian body plan. With an elongated body and a direction of movement the animal has head and tail ends. Sense organs and mouth form the basis of the head. Opposed circular and longitudinal muscles enable peristaltic motion.
The bilaterian gut develops in two ways. In many protostomes, the blastopore develops into the mouth, while in deuterostomes it becomes the anus.
Ecdysis: a dragonfly has emerged from its dry exuviae and is expanding its wings. Like other arthropods, its body is divided into segments.
Spiral cleavage in a sea snail embryo
Jean-Baptiste de Lamarck led the creation of a modern classification of invertebrates, breaking up Linnaeus's "Vermes" into 9 phyla by 1809.
Sides of beef in a slaughterhouse
A gun dog retrieving a duck during a hunt
Artistic vision: Still Life with Lobster and Oysters by Alexander Coosemans, c. 1660

Animals (also called Metazoa) are multicellular, eukaryotic organisms in the biological kingdom Animalia.