Amoebas: Single-celled protozoans with no set body shape. Creates temporary projections called
pseudopods to move and feed. They feed on small organisms via endocytosis, using their
pseudopods to feed.
Some amoebas are parasitic, for example Entamoeba found in tropical regions that can infect
drinking water. This parasite amoeba feeds on the intestinal walls, causing bleeding.
Ciliates:
Protozoates covered with hair like projections called cilia. The cilia move back and forth like oars
to move the organisms through the water. Ciliates have elastic out covering called a pellicle that
maintains their shape. Aquatic and heterotrophic.
The beating of the cilia allows it to swallow its food, and when it reaches the end of the oral
groove, the membrane pinches it off, surrounding the food, and a food vacuole is formed. The oral
groove is the "mouth" of the cilia. The food vacuole travels across the cytoplasm, and eventually
reaches a lysosome with digestive enzymes to break down the food. Then, the usable products are
absorbed, and undigested food is excreted through hthe anal pore.
Paramecia, a type of cilia, have two type of nuclei, a macronucleus and a micronuclei. While the
micronuclei divide through mitosis and macronuceus pinches apart to produce two macronuclei.
They too, are asexually reproducing.
Sporozoans:
Protists that produce spores during asexual phase of reproduction. Non-motile and parasitic,
obtaining nutrients from hosts. One best known sporozoan is Plasmodium, a protest that causes
malaria. These protists after being injected into a human via mosquito transmission, works into
the liver, through the bloodstream and infects blood cells along the way. Malaria is a very serious
disease worldwide and some types can be fatal.
Funguslike Protists
Heterotrophic
Decomposers that feed on dead plants and animals by endocytosis.
Three major phyla: acellular slime moulds, cellular slime moulds, water moulds.
Acellular slime moulds:
Single celled protsists with many nuclei. Mainly a plasmodium in its life. A plasmodium is a wallless mass of cytoplasm that has many nuclei that have divided many times during mitosis. Moves
very slowly over an object with a network of strands called pseudopodia (fake feet) and if the area
is unfavourable (ie no food), it produces reproductive structures called fruiting bodies via meiosis.
The spores scatter and germinate into flagellated cells.
Cellular Slime Mould:
Live in fresh water or decaying matter. Move like amoebalike cells.
When food in scarce, they form multicellular masses, and r eleasing fruiting body forms/spores.
Water Moulds:
Water moulds live in in water. Aquatic and feeds on remains of dead plants and animals. For
example, white mould on dead fish.
Plantlike Protists
24000 speicies of protists that have chlorophyll and can do photosynthesis
Euglenoids: Classified as being both plants and as asnimals. Have unicellular flagellates (animalike)
but also can photosynthesize (plantlike). For example, the Euglena. In the sunlight, it's able to be
autotrophic using chloroplasts to produce sugars but in the dark, it will feed on dead organic
material while losing it chlorophyll.
Algae: Protists that resemble plants because they have chloroplasts with chlorophyll. Single
cellular or multicellular and live in colonies and can agglutinate into massive sizes. For instance,
the Red Sea gets its name from the massive colonies of algae that turn it red.
One group of algae called diatoms have a golden coloration due to yellow/brown pigments in
shells made of silica. Their outer covering is made of two halves that fit together like the lid and bottom of a
shoebox, and each species has a characteristic shape. Diatoms are abundant in the sea, and are a major
food source in marine and freshwater ecosystems.
Dinoflagellates are single cellulared flagella that have two flagella and can be heterotrophic,
through most are photosytnethic. They tend to be luminescent and reproduce asexually.
Dinoflagellates grow rapidly when nutrients in water increase or temperature increases. The
above picture is caused by the dinoflagellate Gonyaulax polyhedron that colours the water red due
to the pigment phycoerthyrin. These dinoflagellates also produce toxins that can harm fish and
shellfish, and be passed onto humans through consumption.
Green algae
Single celled or colonial. Two flagella, which moves it around.
Thought to have given rise to the first plants since they have cellulose and chloroplasts similar to
plants. The bi-flagellated cells of green algae look like the gametes of primitive plants.
The Plant-Protist Divide
Some algae can be classified as either plants or protists. It depends on how the plants are defined.
If plants are defined as multicelluar eukaryotes that perform photosynthesis, then multicellular algae fit the
description, and can be considered plants. But multicellular algae are quite different from plants in many ways.
The vast majority of plants have adaptations for living on land, such as rigid cell walls and specialized organs for
support (roots and stems), and for photosynthesis (leaves). Since multicellular algae are all marine, they do not have
these adaptations and so are considered protists at this time.
The Fungi
Mushrooms and mould are both fungi. Not to be confused with cellular/acellular slime moulds.
Characteristics of Fungi
Contains heterotropic eukaryotes organisms called saprobes. These absorb food from decaying matter, they are
decomposers. These enzymes break down the dead organic matter. Fungi then absorb the digested food through the
cell wall. This method of nutrition is different from slime moulds, which take up their food by simple endocytosis.
The bodies of most fungi consist of threadlike filaments called hyphae. As the hyphae grow, they branch, forming
a tangled mass of filaments called a mycelium that is well adapted to absorb nourishment from its food source. In a
forest, for example, the almost invisible mycelia of fungi obtain nutrients from fallen trees, thus decomposing the
trees. Most hyphae have cell walls. A substance called chitin strengthens the cell walls of fungi instead of cellulose
found in plants.
Reproduction
Fungi can also reproduce asexually or sexually through spores. Spores are haploid cells.
Zygomycota: Fungi with spores in a caselike structure called a sporanglum. Testerial saprobes. Tangled mass of
mycelium grow and produce types of hyphae. Hyphae extend over food surfaces and into the food source. These
hyphae rooted in are called rhizoids. Rhizoids absorb water and sugar from the food source. After a few days, black
caselike structures appear among hyphae called sporangium, capable of producing thousands of spores. These break
open, and carry the s pores airborne, finding idea food sources to germinate on. Under less optimal conditions, these
fungi can also asexual reproduce by producing two genetically different type of hyphae (the plus and minus hyphae).
These join together to form a zygospore, which remains dormant until growing conditions improve.
Ascomycota: Fungi with spores in a sac like structure called an ascus. Includes mildew, moulds and some yeasts.
Sac fungi produce 2 types of spores. Spores produced by sexual reproduction is called ascospores, and asexual
reproduction is called conidia.
Yeast: Yeasts are unicellular, and are grouped with the ascomycetes because they form an ascus in one stage of
their life cycle. Oval shaped and surrounded by a cell wall. Contains a large vacuole and nucleus. Under good
oconditions, they will rapidly reproduce by budding, under poor conditions, yeast reproduce sexually by ascospores.
One useful use of yeast they can tolerate conditions lacking in oxygen and carry out anaerobic
respiration/fermentation. Sugar are broken down by enzymes releasing energy, producing CO2 and alcohol as
byproducts. This fermentation is used in the baking industry to have carbon dioxide that makes dough rize. It is also
used in alcohol fermentation.
Basiodiomycota: Fungi with spores in a club like structure called an ascus. Basiodimycoto include mushrooms,
smuts, puffballs and bracket fungi. They are saprobes or parasites. Under damp conditions in soil or in rotting wood,
the mycelial mass of hyphae form knobs that absorb water and grow quite large. Pushing up through the soil or
perched on rotting logs, these knobs become spore-bearing structures called fruiting bodies. The umbrellalike cap
of each species of mushroom has a characteristic shape and is used as the basis of its classification. The cap
contains many gills, or thin sheets, that radiate out like spokes on a wheel. Each gill bears thousands of clublike
reproductive cells called basidia. These contain several thousand spores and are haploids. When blown by the wind
to suitable ground, they will germinate through cell division. When 2 mycelia join, they fuse creating a dikaryotic
cell, daughter cells with 2 nuclei. Though initially dikaryotic, eventually the nuclei of the cells on the gills fuse to
form diploid cells.
Parasitic rusts and smuts make up another important group of fungi. Smuts cause damage to grain crops such as
corn, oats, wheat, rye, and barle. Parasitic fungi are difficult to control because they have complex reproductive
cycles that often include more than one host. For example, the wheat rust fungus infects the common barberry bush
as well as the wheat plant. Bracket fungi can exist as saprobes on the wood of dead trees, or as parasites on the
wood of living trees. The mycelium of a bracket fungus penetrates and breaks down the woody tissue of its host and,
as it grows, the fungus itself takes on a woody texture. Over the years of its life, the bracket fungus adds additional
layers of hyphae and appears like a shelf extending out from the woody bark of a tree.
Plants