............................. PROTOCTIST KINGDOM AND FUNGI KINGDOM

Introduction. In this chapter we will study the simplest eukaryotic organisms that exist. These are the protozoa, that consists in not more than one cell, and algae and fungi, which both have unicellular species and multicellular species, but they are very simple because all of its cells are practically equal. That is, algae and fungi do not have different types of cells like we do. We need to remember that being simple does not necessarily mean small. In fact living organisms there are more grains algae called "seaweed", living in some tropical seas, and grow to 200 meters long, making them the largest organisms that exist

Protozoa and algae cannot live outside the water or places where there is water, but the fungi can because their cells have a waterproof substance called chitin. Another reason why it is worth studying these groups of organisms, is that some species of protozoa and fungi are responsible for many diseases of plants and animals, including humans. For example the protozoan Plasmodium, which is transmitted by the Anopheles mosquito causing malaria, which is the leading cause of mortality in humans and against which unfortunately still there is no vaccine.


Activities to do. Read explanations of protozoa and algae and perform Multiple Choice Test 12.1, Crossword 12.1. Then read the text on fungi and perform Multiple Choice Test 12.2, Crossword 12.2 and Relate drawings with names 12.1 and 12.2.

1. Protoctist Kingdom.
Includes Protozoa and Algae

1.1 Protozoa. Are eukaryotic unicellular organisms, feeding of organic matter (heterotrophs) that capture and digested inside them. Therefore:

  • There is unicellular algae which do not perform photosynthesis.
  • There is unicellular fungi in which occur external digestion.

They are visible only with a microscope. Its body is delimited by the plasma mem-brane. Some species secrete a substance called extracellular matrix, which often, as happens in the group of foraminifera, is impregnated with mineral substances. Most of protozoa live freely in the water. Some can live inside organisms and often cause disease. They reproduce asexually by bipartition or sporulation. They are classified according to the structures used to move in:



Class Flagellates. Flagella present (long structures, permanent, usually in number of one, two or little more). For example the Trypanosoma that is responsible for the "sleeping sickness" and that is transmitted by the bite of the tsetse fly tropical.

Class Ciliates. Have cilia (flagella-like structures but much shorter and very numerous). For example Paramecium and Vorticella swimmer who lives still.

Class rhizopods. Present pseudopodia (prolongations temporary false shaped body feet). For example the Amoeba and Entamoeba responsible for the "amoebic dysentery" disease of Third World countries and is characterized by bloody diarrhea stools. Some rhizopods as foraminifera have a calcareous skeleton.

Class Sporozoa. They move bodies by simple contractions. For example Plasmodium which is responsible for the "malaria" which is the leading cause of death worldwide. This condition is typical of Third World countries, is characterized by sudden bouts of high fever and is transmitted by the bite of the female Anopheles mosquito.

1.2 The algae
. They are eukaryotes, unicellular or multicellular thallophytic, photosynthetic autotrophs, meaning that they feed on inorganic matter by capturing light energy.

To be Thallophytic multicellular means all of its cells are the same type, it does not possess specialized cells that form different tissues. This kind of structure is called thallus. Because of this lack algae waterproof epidermal tissue to avoid desiccation and, therefore, cannot survive outside the water, unless it is very humid. Some have shapes like leaves, stems and roots but as of lack of the tissue structures internal wires are not true leaves, stems nor roots and cannot be included in the Plant King-dom. This means they are not plants.

They reproduce asexually by bipartition, or by spores fragmentation and sexually by gametes. Generally reproduction is alternate.

Classification is partly by possessing photosynthetic pigments. These can be green (green algae), brown (dark or brown algae) or red (red algae).

Flagellates. They are unicellular and flogged. They are part of the plankton.

Diatomaceous algae. They are unicellular. present a case of silica and a photosynthetic yellowish pigment. They are part of the plankton.

Green algae. They can be unicellular (planktonic) or multicellular (benthic) and predominates the green pigment called chlorophyll.

Brown algae. They are multicellular predominate and brown pigments. They can live attached to the bottom (benthic) or floating in the sea.

Red algae. They are multicellular predominate and red pigments. They are benthic and some carbonates accumulate by contributing to form coral reefs.

Multiple Choice Test

2. Fungi Kingdom
Fungi are eukaryotes, unicellular or multicellular thallus types, that feed on organic matter (heterotrophic) by external digestion.

Morphology. Fungi multicellular filaments consist of cells called hyphae. They together are called the mycelium. In many species of fungi, called fungi superiors, from subterranean mycelium, originates a reproductive organ called mushroom, which can distinguish the foot and cap.

Nutrition. As they feed by external digestion, require places of high organic matter and water. Therefore living in wet locations and without light. Depending on the type of organic matter from which they feed are three types:

  • Saprophytes. They feed on decaying organic matter. For example the champignon.
  • Parasites. They feed on organic matter of live organism. Causing diseases and plagues. For example rusts, blight and ergot attacking cereals, vine mildew and fungus of ringworm, as responsible for the disease "athlete's foot".
  • Symbioses. They feed on the organic matter produced by other organisms which live on mutually benefit associated live in what is called symbiosis. This is the case of fungi of lichens (algae symbiosis with fungi) and mycorrhizal fungi (symbiosis between fungi and plant roots).

Reproduction. Unicellular fungi reproduce asexually by gemmation. The multicellular spores reproduce asexually by genetically identical to the parent, which appear at the end of a special hyphae or sexually by another type of, different from the parent and genetically different spores. In some fungi, such as bread mold, alternating asexual reproduction to sexual reproduction. This is called alternating reproduction.

. Depending on the type of hyphae and spores are three classes:

Bread mold
Phycomycetes fungi or inferiors. Hyphae present without partitions, that is without separating plasma membranes cells. For example vine mildew mobile spores having two flagell and white bread mold having spores without flagella.
Ascomycetes. They present hyphae with septa (septate hyphae) and form spores inside special cells in kit form, called asci, or form filaments called conidia. Some are unicellular as yeasts and some are multicellular like morels, truffles or Penicillium which is the producer of the antibiotic "penicillin".
Basidiomycetes. They present hyphae with septa (septate hyphae) and its spores form on the outside of a special cells called basidia. They are multicellular. Some result in edible mushrooms such as oyster mushroom, milk caps, champignon and mouse. Other mushrooms are toxic, as canaleja, flyswatter and Satan ticket.
Mutiple Choice Test
Connect drawings with names
Connect drawings with names
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