Characterizing and Classifying Eukaryotes Chapter 12

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Characterizing and Classifying EukaryotesChapter
12
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Eukaryotes

• Major groups eukaryotes covered in a Micro course
• Protozoa
• Fungi
• Algae
• Helminths (well save these till later)
• Well cover the medical importance of all of
  these groups in later lectures!

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Classification of Eukaryotic Organisms
Figure 12.4
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Protozoa

• Diverse group defined by three characteristics
• Eukaryotic
• Unicellular
• Lack a cell wall
• With exception of apicomplexans (much more about
  these guys later!), they are motile by means of
  cilia, flagella, and/or pseudopodia

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Distribution of Protozoa

• Require moist environments
• Most live worldwide in ponds, streams, lakes, and
  oceans critical members of plankton
• Others live in moist soil, beach sand, and
  decaying organic matter
• Very few are pathogens

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Nutrition of Protozoa

• Most are chemoheterotrophic
• Obtain nutrients by phagocytizing bacteria,
  decaying organic matter, other protozoa, or the
  tissues of host
• Few absorb nutrients from surrounding water
• Dinoflagellates and euglenoids are sometimes
  considered protozoa but they are photoautotrophic
  and are traditionally grouped with the algae.

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Characteristics of Protozoa
Table 12.2
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Fungi

• Chemoheterotrophic
• Have cell walls typically composed of chitin
• Lack chlorophyll do not perform photosynthesis
• Related to animals
• Reporduction
• All have some means of asexual reproduction
• Most also reproduce sexually

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Significance of Fungi

• Decompose dead organisms and recycle their
  nutrients
• Form beneficial associations with roots of
  vascular plants that help plant absorb water and
  minerals
• Used for food and in manufacture of foods and
  beverages
• Produce antibiotics
• Important research tools
• 30 cause diseases of plants, animals, and humans
• Can spoil fruit, pickles, jams, and jellies

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Fungal Morphology
Figure 12.16a
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Fungal Morphology
Figure 12.16b
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Fungal Morphology
Figure 12.16c
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Nutrition of Fungi

• Acquire nutrients by absorption
• Most are saprobes
• Some trap and kill microscopic soil-dwelling
  nematodes
• Haustoria allow some to derive nutrients from
  living plants and animals
• Most are aerobic some are anaerobic many yeasts
  are facultative anaerobes

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Lichens

• Partnerships between fungi and photosynthetic
  microbes (green algae or cyanobacteria)
• Grow on soil, rocks, leaves, tree bark, other
  lichens, and even on backs of tortoises almost
  every habitat
• Occur in three basic shapes fruticose, crusts,
  foliose
• Important in creation of soil from rocks
• Eaten by many animals

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Makeup of a Lichen
Figure 12.26
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Three Basic Shapes of Lichens
Figure 12.27
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Algae

• Diverse group of photoautotrophic aquatic
  organisms
• Major role in aquatic food chains
• Fix carbon dioxide into organ carbon
• Produce somewhere between 50 and 80 of the
  Earths oxygen
• Morphology Unicellular, colonial, or have simple
  multicellular bodies (thalli)

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Classification of Various Algae
Table 12.4
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Algae Dinoflagellates

• They have two flagella and may have armor
  (cellulose plates) or may be naked (without
  armor). Dinoflagellates have pigments and can
  carry on photosynthesis. Major component of
  phytoplankton.
• Gonyaulax
• Red tide
• Paralytic shellfish poisoning
• Noctiluca miliaris
• Bioluminescent

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Swimming with bioluminescent dinoflagellates
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Algae Bacillariophyta (Diatoms)
Diatoms are sometimes grouped with the golden
algae (Chrysophyta)
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Chrysophyta Golden algae
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Phaeophyta (Brown algae)

• Largest and most complex of the algae
• Kelp is a brown algae
• Giant kelp - up to 100 meters in size
• Seaweeds large, multicellular marine algae of
  coastal waters which include members of the
  Brown, Red, and Green algae groups

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Australian bull kelp (Durvillea potatorum)
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Kelp forest
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Kelp forest
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Red algae (Rhodophyta)
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Chlorophyta (green algae)

• Over 7000 species known
• Freshwater and marine
• Unicellular and multicellular forms
• Volvox
• Chlamydomonas
• Spirogyra