Download Lab 3 Protists and Fungi

Lab 3 Protists and Fungi
September 13, 2011
Taxonomy
We use a number of level to classify organisms. The coarsest level of
organization is the domain. Organisms may be classified as Archea, Bacteria,
or Eukarya. In this class we will examine the Eukarya or organisms with a
true nucleus. The other levels of organization are listed below from coarsest
to finest.
• Domain
• Kingdom
• Phylum
• Class
• Order
• Family
• Genus
• Species
Protists
Protists are a group of organisms that consist of all eukaryotic organisms
that are not plants, animals, or fungi. At one time this was considered to be
a kingdom, however it has now been broken up into many kingdoms. It is
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not a monophyletic group.
You will need to be familiar with a few terms related to movement and
obtaining food. Terms relating to how organisms obtain their food are listed
below:
• autotroph: makes one’s own food from sun or abiotic chemical energy
• heterotroph: obtains food from other organisms
• mixotroph: able to obtain food through autotrophy or heterotrophy
Many single celled organisms use one of the following structures.
• flagella: whip like structures
• cilia: small hair like structures
• pseudopodia: false foot, move by flowing (pseudopod singular)
Eukaryotes have obtained organelles through the process of endosymbiosis. Mitochondria and chloroplasts were obtained by primary endosymbiosis.
Primary endosymbiosis is the forming of a symbiotic relationship with a
prokaryote living inside a eukaryotic cell. Secondary endosymbiosis occurs
when an eukaryote forms an symbiotic relationship with a eukaryotic organism inside its cell.
You should be familiar with the following terms relating to reproduction:
• Asexual reproduction:
– reproduction requiring only one organism to reproduce, reproduction without sex
• Sexual reproduction:
– is reproduction that uses the fusion of nuclei from different cells
cells to reproduce. In short they use sex to reproduce. This usually
involves two organisms, but occasionally will involve the combination of reproductive cells from the same organism.
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– When they are two different mating types we refer to them as +
and - if they are the same size. If the gametes or sex cells are
different sized than we refer to them as male and female. The
female is the large gamete and the male is the small gamete.
• mitosis: Process of cell division that produces 2 diploid daughter cells
• meiosis: Process of cell division that produces 4 haploid daughter cells
You should be familiar with the 5 main groups of organisms listed below.
Archaeplatida
This group consists of photoautotrophs including red and green algae and
plants. This group are important primary producers.
• Red algae
– Red algae have red colored pigments which mask the green of their
chloroplasts. These include many of the algae that we eat such as
in sushi.
• Green algae
– Consist of two groups Chloropytes and Charophyceans.
– Charophyceans are the closest relatives to land plants. Green
algae are not a monophyletic group because Charophyceans are
more closely related to land plants than Chlorophytes
• Land Plants will be discussed in next weeks lab. This is one of two
groups that shows a true alternation of generations. That is they have
multicellular haploid and diploid stages.
Chromalveolata
This group results from a secondary Endosymbiosis with a red algae.
• Dinoflagellates have 2 flagella. These are the organisms that cause red
tides.
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• Apicomplexans are an important group because they contain the parasite Plasmodium (malaria)
• Ciliates have cilia which they use for locomotion. Paramecium is an
example of this taxa.
• Oomycetes, were once classified as fungi. These contain important
plant pathogens such as potato late blight and sudden oak death.
• Diatoms are responsible for diatomous earth. They are important primary producers in our oceans. And are also important for carbon
sequestraition because they decompose slowly.
• Golden Algae
• Brown Algae is a group of multicellular algae. They provide important
marine habitat. They are one of two taxonomic groups to have a true
alternation of generations.
Excavata
This group contains many important human paracites.
• Diplomanads include the gastrointestinal parasite Giardia.
• Parabasalids include the termite symbionts that allow them to digest
cellulose.
• Euglenozoans include the parasites
– Leishmania
– and Trypanosoma brucei: african sleeping sickness.
Rhizaria
are amoeba like with root looking pseudopodia. They include:
• Chlorarachniophytes
• Forams
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• Radiolarians
Unikonata
Unikonata includes the following groups.
• Amoezoans
– Slime molds
– Gymnamoebas
– Entamoebas, which include the causes of amebic dysentery
• Opisthokonts
– Nucleariids
– Fungi
– Choanoflagellates
– animals
Fungi
Fungi are heterotrophs that have cell walls made of chitin. Chitin is the
same material that makes up the exoskeletons of insects. They may reproduce sexually, asexually or both sexually and asexually.
Hyphae: tiny filaments which make up the bodies of fungi.
Mycelium: an interwoven mass of hyphae
Mycorrhizae: (fungus roots) mutualistic relationships between fungi and
plant roots
Ectomycorrhizae: form sheaths of hyphae over the surface of the root to
exchange nutrients with the plant.
Arbuscular mycorrhizae: extend hyphae through the cell wall to exchange
nutrients with the plant.
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Figure 1: fungal lifecycle
Heterokaryon or heterokaryotic stage: cells contain 2 or more haploid nuclei
Dikaryotic: cell containing 2 nuclei
fungal lifecycle
Important terms for fungal lifecycle
• Plasmogamy: fusion of cytopalsm
• Karyogamy: fusion of nucleaus
Fungi
• Chytrids
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• Zygomycetes
• Glomeromycetes
• Ascomycetes
• Basidiomycetes
There are 5 phyla of fungi.
Basidiomycetes
Distinguished by their fruiting body called a Basidiocarp. These are
the most recognizable fungi. They include important decomposers, plant
pathogens, and edible mushrooms. Some examples are:
• Portabella and common white mushrooms
• club fungi
• fairy rings and puffballs
• wheat rust
Ascomycetes
Ascomycetes are the sac like fungi. They have a sac like fruiting body
called an ascocarp. They include edible mushrooms, plant pathogens, mychorhizae and human pathogens. Some examples are:
• morells and truffels
• Claviceps purpurea, ergot
• yeast
• Some fungi in the genus Trichophyton cause athlete’s foot.
• Penicillium from which penicillin is obtained
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Zygomycetes
This phylum of fungi is named for its heterokaryotic stage the Zygosporangium which can survive harsh conditions for long periods of time. An
example is black bread mold.
Glomeromycites
This phylum was once grouped in with the zygomycetes, but it has now
been placed in its own monophyletic group based on genetic information.
Most fungi in this taxon are arbuscular mycorrhizae.
Cytrids
This group is most likely paraphyletic, consisting of more than one clade
or monophyletic group. This group is unique in that they have flagellated
spores called zoospores. Some live in the digestive tracts of sheep and cattle
and help break down plant matter.
For your quiz:
• know how to calculate your microscope magnification: ocular lens magnification * objective lens magnification
• know the definitions given
• know the general fungal lifecycle
• be able to list a protist and a fungus that is harmful to people and one
that is beneficial to people and be able to list what group it belongs
to. You must be more specific than Fungi or protist.
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