What are multicellular organisms made of
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
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 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.
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
only have vacuoles in exceptional cases
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
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.
eukaryotic unicellular organisms, protists, rhizopodia (root pods)
up to 15cm, average at 200-500 µm
Sea, temperature does not matter (there are both arctic and tropical species), salinity is important; optimal 45 ‰
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
with algae à therefore they need light so that algae can photosynthesize
Algae, trace elements (iron, silicon, mercury, titanium and strontium)
sessile (= settled), planktonic (= float freely in the water), benthic (on the sea floor)
Species richness: 10,000 species and 903 genera
eukaryotic unicellular organisms, protists, amoebas
0.1 - 2mm
almost everywhere (also in the air!), but most of them are in damp soil or in water
Surrounded by a thin cell membrane, in it thick and clear cell plasma (= outer plasma), inside the cell thin, cloudy inner plasma
University of Vienna: Amoebas as a “Trojan horse” for pathogens
In the amoeba, the food (bacteria and other unicellular organisms) is absorbed into the cytoplasm and digested through a vacuole
eukaryotic protozoa, ciliates, oligohymenophorea, paramecia
0.05 - 0.32mm
Domestic waters (e.g. ponds, ponds, lakes, rivers, but also in puddles) are an important part of the ecosystem
similar to a slipper
often with green algae
“Favorite food”: bacteria
rhythmic flutter of eyelashes
Arise in the hay infusion
eukaryotic unicellular organisms, flagellates
Waters (different types depending on their quality), damp places, snow
one or a few typical flagella (lat. flagella): hence the name
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
by means of a scourge
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
eukaryotic protozoa, spore animals
Sporozoa live parasitically in hosts (they take advantage of them)
Sporozoa ingest food that has been dissolved through the cell surface
smooth movement without flagella, eyelashes, etc.
Reproduction: Mixing between sexual and asexual reproduction
http://www.zum.de/Faecher/Bio/SA/stoff7/amoebe.htmCompilation: David Dopplinger, Johannes Lehner, Martin Meingassner
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