Bacteria Basics (Chapter 27)
Bacteria Basics (Chapter 27)
I. 3 Domains (above kingdom classification): Archaea, Bacteria, Eukarya
A. Archaea – earliest prokaryotes, live in hot springs, salt ponds, places that
mimic conditions of early earth,
B. Bacteria – All other prokaryotes
C. Eukarya – all eukaryotes
II. Cell Walls made of peptidoglycan
A. Gram-positive – simpler walls with lots of peptidoglycan
B. Gram-negative – less peptidoglycan, more complex
C. Capsule – sticky protective layer outside cell, allows cell to stick to substrates
and other cells, resistance to pathogens.
D. Pili – appendages that allow some prokaryotes to stick to surfaces or other
prokaryotes, like during conjugation.
III. Movement – about ½ of prokaryotes are motile
A. Flagella – skinnier than eukaryotic flagella
B. Spirochetes – group of bacteria that move like corkscrews
C. Taxis – movement toward or away from stimulus (ex. Phototaxis)
IV. Structure of cell
A. Lack organelles, but have infolded membranes for metabolic functions
B. DNA in nucleoid region, one double stranded ring, plasmids (only a few genes)
V. Reproduction/Genetic Variation
A. Binary fission – one cell divides into 2
B. Transformation – genes taken up from surrounding environment
C. Conjugation – genes transferred directly from one prokaryote to another
D. Transduction – genes transferred from one prokaryote to another by a virus
E. Mutation – source of genetic variation
F. Endospores – durable wall surrounding prokaryotic chromosome (autoclave
kills endospores)
VI. Obtaining energy/nutrition
A. Photoautotrophs – photosynthetic
1. Nitrogen fixation – convert atmospheric nitrogen to ammonia (others
besides just photoautotrophs do this, too)
B. Chemoautotrophs – oxidize inorganic substances (ammonia, sulfur, etc.) to
gain nutrition from CO2 – don’t need light energy
C. Photoheterotrophs – use light to generate ATP, but need to obtain carbon in
organic form
D. Chemoheterotrophs – must consume organic molecules for both energy and
Carbon
1. Saprobes – decomposers
2. Parasites – take from living hosts
VII. Oxygen
A. Obligate aerobes – need oxygen for cellular respiration
B. Facultative anaerobes – use oxygen if present, but can use fermentation
C Obligate anaerobes – poisoned by oxygen – use fermentation or anaerobic
respiration
VIII. Symbiosis – relationships between species in direct contact
A. Mutualism – both benefit ex) bacteria in digestive and reproductive tracts
B. Commensalism – one benefits, other no change ex) bacteria on animals
C. Parasitism – one benefits, other suffers ex) disease
1. opportunistic – live there all the time, but cause illness when host weakened
2. Koch – identified bacteria responsible for anthrax and tuberculosis.
Koch’s postulate: pathogen is cause of disease if: 1) same pathogen in each diseased indiv.
2) isolate pathogen and grow in culture 3) induce disease in other animals 4) isolate from
experimental animals after disease develops.
D. Exotoxins – released by prokaryotes, can produce disease symptoms without presence of bacteria.
VIII. For each of the following describe how they are unique in their lifestyle and adaptations they might have.
- methanogens
- halophiles
- thermophiles
- Rhizobia
- Cyanobacteria
- Psudomonas
- E. Coli
H. Chlostridium
Protista Basics (Chapter 28)
I. Most diverse eukaryotes
A. Protozoa – ingestive, animal-like
B. absorptive, fungus-like
C. Algae – photosynthetic, plant-like
II. Characteristics
A. Most are motile
B. Some asexually, some sexual
C. Found everywhere there is water
III. Endosymbiosis – Eukaryotes evolved from prokaryotes when ancestral prokaryotes engulfed other prokaryotes
A. Endomembrane system – infolding for plasma membrane to make ER and golgi
B. Mitochondria and chlorplasts – similar DNA to bacteria, double membranes, size similar to
bacteria, replicate independent of cell
IV. Origination of multicellularity
A. Multiple multicellular organisms evolved independently
1. Plants – descended from multicellular algae
a. intermediate – Volvox, green algae live in cooperative colonies
2. Animals – descended from multicellular protozoans
3. Fungi – descended from multicellular absorbers
Fungus Basics (Chapter 31)
I. Absorption – small organic molecules absorbed form surrounding medium
A. Decomposers – saprobes, absorb nutrients from nonliving organic material (logs, dead animals, waste)
B. Parasites – absorb nutrients from the cells of living hosts, can be pathogenic
C. Mutualistic – absorb nutrients from a host, give some benefit to host ex) aid uptake of mineral
II. Adaptations
A. Vegetative (nutritional) bodies underground – can be HUGE, but we don’t see it
1. hyphae – threads of tubular walls surrounding plasma membranes and cytoplasm
2. mycelium – interwoven mat of hyphae, feeding network of fungus
B. Organization
1. septa – crosswalls that separate sections of hyphae
2. chitin – composes cell wall of fungus
3. coenocytic fungus – no divisions, continuous cytoplasmic mass with tons of nuclei
4. haustoria – hyphae of parasitic fungi, penetrates tissue of host
C. Reproduction
1. Asexual – Mycelium sends out spore producing structures, which send out spores, which germinate
to produce mycelium
2. Sexual – Mycelium of 2 individuals come together, cytoplasm fuses (plasmogamy, n+n, dikaryon),
nuclei fuse
(karyogamy, 2n), meiosis to send out spore producing structures, which send out spores, spores
germinate to form mycelium
III. Impact of fungus
A. Decomposers – keep ecosystems stocked with inorganic nutrients, also try to decompose our food – Doh.
B. Pathogens – diseases caused by fungus
1. Plants – Dutch elm disease, American chestnut blight
2. Animals – athletes foot, yeast infections