Download Mr. Martin`s Unit 5 PowerPoint #2

Bacteria and Viruses, Protista,
and Fungi
Chapters 22, 23, 24
The new Three Domain System
To which domain is prokaryotic Archaea more closely related?
I. Why put prokaryotic Archaea in a separate domain?
Archaebacteria
• Methanogens
– Swamps, sewage
• Halophiles
– Brackish ponds, salt lakes, hydrothermal seafloor
vents
• Extreme Thermophiles
– Acidic soils, hot springs, coal mines,
hydrothermal vents
Optical Illusion
II. Viruses
A. Introductory information
a. Definition = “obligate intracellular parasites”
b. Tobacco mosaic virus was crystallized and first
seen with TEM in 1935.
B. Structure
a. Capsid – protein coat, composed of protein
subunits, form rods, polyhedrons, and complex
structure
b. Envelope – found in viruses that infect animals,
outer membrane derived from host cell
c. Genome – DNA or RNA
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C. Lytic cycle of a T4 bacteriophage
Animation E
Summary of the entire lytic life cycle of a bacteriophage.
D. Lysogenic cycle (latent period viruses)
a. After insertion, viral DNA incorporates
itself into a specific site within the bacterial
DNA (viral DNA is now called a prophage)
b. Prophage is replicated during every
subsequent cell division of the bacterium
c. Prophages sometimes make harmless
bacteria toxic, e.g. diphtheria, botulism,
scarlet fever
d. Occasionally prophage leaves bacterial
chromosome and becomes lytic
E. Replication of animal viruses (contain DNA or RNA)
(Note that cell is not destroyed and source of envelope.)
(This is an influenza (flu) virus)
III. Protista
A. Origin of eukaryotes—endosymbiont hypothesis
-capture and subsequent symbiotic relationship
between large heterotrophic eukaryote and small
heterotrophic and photosynthetic prokaryotes
B. Major types of protists
1. Protozoans—one-celled heterotrophs
a. Flagellates-move with one of more
flagella, Giardia, trypanosomes
b. Amoebas-move and feed by pseudopodia
c. Ciliates-move and feed with cilia, freeliving, two nuclei, Paramecium
d. Apicomplexans-all parasitic, Plasmodium
2. Slime molds—have
unicellular and
multi-cellular life stages
3. Algae—photosynthetic protists
a. Diatoms-unicellular, glassy cell walls
containing silica
b. Dinoflagellates-unicellular, two flagella
c. Green algae-unicellular
Chlamydomonas, colonial Volvox
4. Seaweeds—large, marine, multicellular bodies
a. Brown algae-largest, kelp (100 m.)
b. Red algae
c. Green algae-multicellular
V. Fungi
A. General characteristics
1. Eukaryotic
2. Absorptive heterotrophs
3. Reproduce sexually and asexually (spores)
B. Structural characteristics
1. Some are unicellular (yeast)
2. Most have a thallus (body) called a mycelium,
which is composed of hyphae, which are
a. Filamentous, and
b. Septate or aseptate
3. Often found in symbiotic relationships
a. Lichens (fungi + algae) and plant roots, helps plant
take up nutrients