What are multicellular organisms made of

See

Unicellular organisms

Definition of unicellular organisms:
Protozoa are microorganisms that, as the name suggests, only consist of one cell. Although they are neither organs nor other essential components of animals, they still have all the abilities that make up living things: metabolism, growth, reproduction, movement and irritability.
With the formation of protozoa in the deep sea 3.5 billion years ago - according to the latest research - biological evolution began on earth. There are various theories about this origin of life

(see http://www.planet-wissen.de/pw/Artikel,,,,,,,059DE32197553432E0440003BA5E08D7,,,,,,,,,,,,,,,.html)

Classification of the cells:
The unicellular organisms are divided into the so-called prokaryotic and eukaryotic cells, whereby the prokaryotes do not have a real cell nucleus (the DNA floats around freely in the cell plasma) and the eukaryotes already have one (the DNA is anchored there). We only want to deal with the latter in more detail on this homepage.

Eukaryotes:
Eukaryotes in turn consist of 3 different subgroups: the plant, animal and fungal cells, which have the following differences:

Differences between plant, animal and fungal cells
Animal cells, plant cells, and fungal cells belong to the group of eukaryotic cells, but there are some differences in their structure. The most important differences are listed in a table below.
The cells of mushrooms occupy a special position.

plant cells

animal cells

Fungus cells

are enclosed by a cell wall made of cellulose

do not have a cell wall

are enclosed by a cell wall

contain chloroplasts or other plastids

do not have chloroplasts or other plastids

do not have chloroplasts or other plastids

have vacuoles

only have vacuoles in exceptional cases

have vacuoles

divide by constriction of the cell membrane and the formation of a new cell wall between the daughter cells

divide by constriction between the daughter cells by means of cell membrane constriction

 

are partly connected to each other via plasmodesmata, which are retained as open connections during cell division.

are connected to one another via desmosomes and various other structures ("cell junctions") that have emerged as new formations after the cells have completely divided

 

no lysosomes present

have lysosomes, which in many cases take over the tasks of the lytic vacuoles

 

Protists
The eukaryotic unicellular organisms are grouped under the term protists. Today these are assigned to a separate realm of living beings and do not belong to plants, animals or fungi. But there are also multicellular protists. Protists include single or multicellular algae, slime molds and unicellular protozoa.

Like all living beings, protists consist of cytoplasm as a living substance and are surrounded on the outside by a cell membrane. In the cytoplasm there is usually a nucleus to control life processes, occasionally there are also several nuclei; Furthermore, the cytoplasm contains mitochondria and, in the case of phototrophic protists (these carry out photosynthesis), one or more chloroplasts. With some Protists there are also shell formations on the outside; many can form cyst envelopes to withstand adverse environmental conditions. The cells are usually very small in size, and only a few reach a diameter of several millimeters or even centimeters.
The locomotion is often swimming with the help of flagella or eyelashes or creeping, sliding, flowing or striding through the formation of pseudopods. Quite a few species just float in the water, floating is often supported by long cell processes.

Most protists live in the sea on the surface or floating in the water, crawling on the bottom or stuck to stones, plants and the like; others are found in fresh water, few on land.

We now want to introduce the most important protists.

Foraminifera (chamberlings)

http://www.bgr.bund.de/cln_006/nn_326448/DE/Themen/GG__Palaeontol/Fossilgr/Foraminiferen/foraminiferen__
node.html? __ nnn = true

Systematics

eukaryotic unicellular organisms, protists, rhizopodia (root pods)

size

up to 15cm, average at 200-500 µm

habitat

Sea, temperature does not matter (there are both arctic and tropical species), salinity is important; optimal 45 ‰

construction

Shell: cemented foreign bodies, calcium carbonate, Rotaliina (shell made of calcite or aragonite, with pores) à good preservation in sedimentary rocks and is therefore often used as a guide fossil
there are one or more chambers in the housing

symbiosis

with algae à therefore they need light so that algae can photosynthesize

food

Algae, trace elements (iron, silicon, mercury, titanium and strontium)

Locomotion

sessile (= settled), planktonic (= float freely in the water), benthic (on the sea floor)

useful information

Species richness: 10,000 species and 903 genera
first finds in rock formations of the Cambrian; therefore they are very important in paleontology

Amoeba

http://upload.wikimedia.org/wikipedia/commons/d/d8/Chaos_diffluens.jpg

Systematics

eukaryotic unicellular organisms, protists, amoebas

size

0.1 - 2mm

habitat

almost everywhere (also in the air!), but most of them are in damp soil or in water

construction

Surrounded by a thin cell membrane, in it thick and clear cell plasma (= outer plasma), inside the cell thin, cloudy inner plasma
Amoebas are constantly changing their shape and forming pseudopods for locomotion

symbiosis

University of Vienna: Amoebas as a “Trojan horse” for pathogens

food

In the amoeba, the food (bacteria and other unicellular organisms) is absorbed into the cytoplasm and digested through a vacuole

Locomotion

Pseudopod

useful information

asexual reproduction
Causes of amoebic dysentery (= infection of the intestine, in which the intestinal cells die)

Paramecum (paramecium)

http://nikoninstruments.mediaroom.com/file.php/140/IOD_VanEgmond-10430-1.jpg

Systematics

eukaryotic protozoa, ciliates, oligohymenophorea, paramecia

size

0.05 - 0.32mm

habitat

Domestic waters (e.g. ponds, ponds, lakes, rivers, but also in puddles) are an important part of the ecosystem

construction

similar to a slipper
2 cell nuclei: macro- (controls life processes) and micronucleus (ensures the exchange of the chromosome set with the partner during the sexual process)
contractile vacuoles (to remove excess water)
characteristic eyelashes on the edge
Oral area, cell extractor for digestion

http://upload.wikimedia.org/wikipedia/de/f/f9/Pantoffeltierchen.jpg

symbiosis

often with green algae

food

“Favorite food”: bacteria
These are transported with the help of the eyelashes to the mouth area in a food vacuole and digested there by various chemical processes with enzymes and acidification; the food vacuole migrates through the cell
Usable substances are absorbed, useless substances are excreted by the cell extractor

Locomotion

rhythmic flutter of eyelashes

useful information

Arise in the hay infusion
Paramecium was unicellular of the year 2007

 

Flagellates (flagellates)

http://www.awi.de/fileadmin/user_upload/Discover/Click_Learn/Leben_im_Wattenmeer/Geisseltierchen.jpg

Systematics

eukaryotic unicellular organisms, flagellates

size

85-115 µm

habitat

Waters (different types depending on their quality), damp places, snow

construction

one or a few typical flagella (lat. flagella): hence the name

symbiosis

with termites (flagellates produce digestive enzymes that help bacteria in the cell plasma to split wood à symbiosis between 3 groups of organisms!): without flagellates, termites could not cause any damage
http://www.g-o.de/dossier-detail-60-12.html

food

heterotrophic:
mainly bacteria, but also other protozoa and algae
different intake: sessile forms swirl, some catch bacteria individually
Food is enclosed in the cell wall and then digested by vesicles
autotrophic:
carry out photosynthesis with chloroplasts
some can do both

Locomotion

by means of a scourge

useful information

best-known flagellates: eye animals (Euglena)

some types (e.g. Trichomonas vaginalis) cause kidney inflammation, intestinal inflammation and mucosal infections or cause deformities of the skin or organs (= leishmaniasis, pathogen leishmania) http://faculty.southwest.tn.edu/jiwilliams/euglena.jpg
Caused by white droppings in ornamental fish
are used to determine the water quality, as specific flagellates occur in every body of water depending on the degree of pollution

 

Sporozoa (Sporozoa)

* Arrows indicate sporozoa (here: Plasmodium)
http://library.thinkquest.org/03oct/00946/pic_used/avian_plasmodium.jpg

Systematics

eukaryotic protozoa, spore animals

size

 

habitat

in hosts

construction

easy construction:
no movement and food organelles
some form cystic envelopes

symbiosis

Sporozoa live parasitically in hosts (they take advantage of them)

food

Sporozoa ingest food that has been dissolved through the cell surface

Locomotion

smooth movement without flagella, eyelashes, etc.

useful information

Reproduction: Mixing between sexual and asexual reproduction
Malaria pathogen (Plasmodium): nest in red blood cells, cause them to burst and occupy new ones again

http://www.zum.de/Faecher/Bio/SA/stoff7/amoebe.htm

Compilation: David Dopplinger, Johannes Lehner, Martin Meingassner