A report on Multicellular organism

A Caenorhabditis elegans stained to highlight the nuclei of its cells
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Organism that consists of more than one cell, in contrast to a unicellular organism.

- Multicellular organism
A Caenorhabditis elegans stained to highlight the nuclei of its cells

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Eukaryote

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

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

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 may be either unicellular or multicellular, and include many cell types forming different kinds of tissue; in comparison, prokaryotes are typically unicellular.

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

Cell (biology)

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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

Organisms can be classified as unicellular (consisting of a single cell such as bacteria) or multicellular (including plants and animals).

Algae

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Informal term for a large and diverse group of photosynthetic eukaryotic organisms.

Informal term for a large and diverse group of photosynthetic eukaryotic organisms.

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

Included organisms range from unicellular microalgae, such as Chlorella, Prototheca and the diatoms, to multicellular forms, such as the giant kelp, a large brown alga which may grow up to 50 m in length.

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

Organism

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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.

Organisms are classified by taxonomy into groups such as multicellular animals, plants, and fungi; or unicellular microorganisms such as protists, bacteria, and archaea.

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

Unicellular organism

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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

A unicellular organism, also known as a single-celled organism, is an organism that consists of a single cell, unlike a multicellular organism that consists of multiple cells.

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

Animal

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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
Auroralumina attenboroughii, an Ediacaran predator (c. 560 mya)

Animals are multicellular, eukaryotic organisms in the biological kingdom Animalia.

Fungus

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Any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms.

Any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms.

Fungal cell cycle showing Dikaryons typical of Higher Fungi
Omphalotus nidiformis, a bioluminescent mushroom
Bracket fungi on a tree stump
In 1729, Pier Antonio Micheli first published descriptions of fungi.
Armillaria solidipes
Mold growth covering a decaying peach. The frames were taken approximately 12 hours apart over a period of six days.
Polyporus squamosus
The 8-spore asci of Morchella elata, viewed with phase contrast microscopy
The bird's nest fungus Cyathus stercoreus
Prototaxites milwaukeensis (Penhallow, 1908)—a Middle Devonian fungus from Wisconsin
Main groups of fungi
Arbuscular mycorrhiza seen under microscope. Flax root cortical cells containing paired arbuscules.
Diagram of an apothecium (the typical cup-like reproductive structure of Ascomycetes) showing sterile tissues as well as developing and mature asci.
A pin mold decomposing a peach
The dark filaments are hyphae of the endophytic fungus Epichloë coenophiala in the intercellular spaces of tall fescue leaf sheath tissue
The lichen Lobaria pulmonaria, a symbiosis of fungal, algal, and cyanobacterial species
The plant pathogen Puccinia magellanicum (calafate rust) causes the defect known as witch's broom, seen here on a barberry shrub in Chile.
Gram stain of Candida albicans from a vaginal swab from a woman with candidiasis, showing hyphae, and chlamydospores, which are 2–4 µm in diameter.
Ergotamine, a major mycotoxin produced by Claviceps species, which if ingested can cause gangrene, convulsions, and hallucinations
Saccharomyces cerevisiae cells shown with DIC microscopy
The mold Penicillium rubens was the source of penicillin G.
A selection of edible mushrooms eaten in Asia
Stilton cheese veined with Penicillium roqueforti
Amanita phalloides accounts for the majority of fatal mushroom poisonings worldwide. It sometimes lacks the greenish color seen here.
Grasshoppers killed by Beauveria bassiana

Growth of fungi as multicellular structures consisting of somatic and reproductive cells—a feature independently evolved in animals and plants —has several functions, including the development of fruit bodies for dissemination of sexual spores (see above) and biofilms for substrate colonization and intercellular communication.

Cell division in prokaryotes (binary fission) and eukaryotes (mitosis and meiosis)

Cell division

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Process by which a parent cell divides, when a mother cell divides into two or more daughter cells.

Process by which a parent cell divides, when a mother cell divides into two or more daughter cells.

Cell division in prokaryotes (binary fission) and eukaryotes (mitosis and meiosis)
Divisome and elongasome complexes responsible for peptidoglycan synthesis during lateral cell-wall growth and division.
Image of the mitotic spindle in a human cell showing microtubules in green, chromosomes (DNA) in blue, and kinetochores in red
Cell division over 42. The cells were directly imaged in the cell culture vessel, using non-invasive quantitative phase contrast time-lapse microscopy.
Kurt Michel with his phase-contrast microscope

On a larger scale, mitotic cell division can create progeny from multicellular organisms, such as plants that grow from cuttings.

Red algae

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Red algae, or Rhodophyta, are one of the oldest groups of eukaryotic algae.

Red algae, or Rhodophyta, are one of the oldest groups of eukaryotic algae.

Rhodophyta (red algae)
Cyanidium sp. (Cyanidiophyceae)
Porphyra sp., haploid and diploid (Bangiophyceae)
Chondrus crispus (Florideophyceae: Gigartinales)
Gracilaria sp. (Florideophyceae: Gracilariales)
Corallina officinalis sp. (Florideophyceae: Corallinales)
Laurencia sp. (Florideophyceae: Ceramiales)
Some red algae are iridescent when not covered with water

The majority of species (6,793) are found in the Florideophyceae (class), and mostly consist of multicellular, marine algae, including many notable seaweeds.

Clockwise from top left: Blepharisma japonicum, a ciliate; Giardia muris, a parasitic flagellate; Centropyxis aculeata, a testate (shelled) amoeba; Peridinium willei, a dinoflagellate; Chaos carolinense, a naked amoebozoan; Desmarella moniliformis, a choanoflagellate

Protozoa

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Informal term for a group of single-celled eukaryotes, either free-living or parasitic, that feed on organic matter such as other microorganisms or organic tissues and debris.

Informal term for a group of single-celled eukaryotes, either free-living or parasitic, that feed on organic matter such as other microorganisms or organic tissues and debris.

Clockwise from top left: Blepharisma japonicum, a ciliate; Giardia muris, a parasitic flagellate; Centropyxis aculeata, a testate (shelled) amoeba; Peridinium willei, a dinoflagellate; Chaos carolinense, a naked amoebozoan; Desmarella moniliformis, a choanoflagellate
Class Protozoa, order Infusoria, family Monades by Georg August Goldfuss, c. 1844
John Hogg's illustration of the Four Kingdoms of Nature, showing "Primigenal" as a greenish haze at the base of the Animals and Plants, 1860
The ciliate Spirostomum ambiguum can attain 3 mm in length
Isotricha intestinalis, a ciliate present in the rumen of sheep.
Paramecium bursaria, is one example of a variety of freshwater ciliates that host endosymbiont chlorophyte algae from the genus Chlorella
Resting cyst of ciliated protozoan Dileptus viridis.
Life cycle of parasitic protozoan, Toxoplasma gondii
Trophozoites of the amoebic dysentery pathogen Entamoeba histolytica with ingested human red blood cells (dark circles)

Originally, the group included not only single-celled microorganisms but also some "lower" multicellular animals, such as rotifers, corals, sponges, jellyfish, bryozoa and polychaete worms.