Download lecture notes – 2007, bly 122, o`brien

LECTURE NOTES – 2007, BLY 122, O’BRIEN
I.
Bacteria and Archaea (Chapter 27)
A.
Characteristics of Bacteria & Archaea compared to Eukaryotes (See Table
27.2)
1.
Characteristics common to Bacteria & Archaea (Two together are
known as “prokaryotes”)
a)
No membrane-bound organelles
(1)
No chloroplasts
(2)
No mitochondria
(3)
No nucleus
b)
One circular chromosome
2.
Both Archaea & Eukaryotes have many complex RNA
polymerases
3.
Archaea have unique cell walls that lack peptidogylcan (= proteinsugar complexes) found in bacterial cell walls Picture Slide: Figure
27.12a
4.
Eukaryotes
a)
Characteristics
(1)
Cell have organelles surrounded by membranes
(2)
Cells have nuclei
b)
Most multi-celled animals and plants are eukaryotes
c)
However, most eukaryotes are single-celled organisms
known as . . .
(1)
Protists
(2)
Protistans
(3)
Protozoans
5.
Fossil record
a)
Earth approximately 4.5 billion years old
b)
Bacteria were present 3.4 billion years ago
c)
Archaea & eukaryotes appeared about 1.7 billion years ago
B.
Bacterial Diseases
1.
Koch’s postulates developed in late 1800s
a)
Pathogen must be present in sick organisms and absent
from healthy ones
b)
Pathogen must be isolated and cultured from sick organism
c)
Symptoms of disease appear in healthy host following
infection with cultured pathogen
d)
Pathogen must be isolated from experimentally infected
host.
2.
Significance of Koch’s postulates
a)
Established modern era of medicine
b)
Basis for germ theory of infectious diseases
3.
Some alternative theories explaining illness
a)
Imbalance of body fluids
(1)
Humoral Theory of ancient Greeks
1
(a)
Phlegm - Phlegmatic people are not easily
aroused
(b)
Blood or sanguis - Sanguine people are
cheerful and have sturdy temperaments
(c)
Yellow Bile or choler - Choleric people are
hot-tempered
(d)
Black Bile or melancholia - Melancholy
means sad.
Picture Slide: Hippocratic Doctrine of 4 Fluids (Picture not in text)
(2)
Blood-letting removes “bad blood”
Picture Slide: Blood-letting using a leech (Picture not in text)
b)
Imbalance of body energies
(1)
Acupuncture attempts to restore balanced of yinyang
(2)
Chiropractic medicine attempts to restore nerve
activity
c)
Possession by evil spirits
d)
Punishment for transgressions
4.
Indiscriminate use of antibiotics
a)
Resistance to antibiotics is increasing
b)
Antibiotics only affect bacteria, not viruses
Word Slide: “ …The landmark pink hospital, Tripler Army Medical Center in Honolulu, bustles with
modern medicine and coordinated public health, and if you want to find explosive evolution, you should
look in a place like this. Here you will find tuberculosis that has resisted treatment, strep throats that have
shrugged off erythromycin, and a chilling post-operative infection called methicillin-resistant
Staphylococcus aureus that can slip into a recovery room and kill after surgery. AIDS patients arrive for
checkups, each carrying with them a self-contained arms race between their immune system and HIV, a
race that runs on evolutionary fuel, with a grim finish line. . . . No hospital in the world can ignore drug
resistance, and drug resistance is evolution come to life.” From Stephen Palumbi, S.R. (2001) The
Evolution Explosion: How Humans Cause Rapid Evolutionary Change, W.W. Norton & Co.; p. 5
C.
D.
E.
Global Change
1.
Cyanobacteria photosynthesis probably produced the first
significant amounts of oxygen gas on earth Picture Slide: Fig. 27.3
2.
Bacteria & Archaea carry out mineral nutrient recycling upon
which all organisms depend
a)
Plant growth often limited by availability of nitrogen
b)
Bacteria and Archaea only known organisms that can fix
nitrogen (= convert nitrogen gas to a form that can be used
by eukaryotes) Picture Slide: Fig. 27.14
Phylogeny of bacteria, Archaea & eukaryotes
1.
Morphological differences between prokaryotic cells are minimal
2.
Phylogeny accepted today was determined by comparison of
ribosomal RNA gene sequences Picture Slide: Compare Fig. 27.1
with Fig. 27.9
a)
Bacteria diverged first
b)
Archaea more closely related to eukaryotes than to bacteria
Morphological Diversity
2
1.
Gram-positive bacteria have a cell wall with abundant
peptidoglycan. Picture Slide: Fig. 27.12a
2.
Gram-negative bacteria have thin, gelatinous cell wall with
peptidoglycan surrounded by a phospholipid bilayer. Picture Slide
Fig. 27.12b
3.
These two can be distinguished by a Gram stain that reacts with the
peptidoglycan. Picture Slide Fig. 27.12c
a)
The Gram stain colors the cell wall of Gram-positive
bacteria purple.
b)
The Gram stain cannot reach the peptidoglycan in the
Gram-negative cell wall, so it stains pink.
F.
Metabolic Diversity is Greatest in Prokaryotes
1.
Eukaryotes
a)
Plants use one biochemical system to synthesize sugar from
carbon dioxide
b)
Animals cannot convert CO2 to sugar
c)
Animals can only obtain carbon from other organisms
2.
Bacteria and Archaea
a)
Obtain carbon from organic and inorganic sources
b)
Use many different electron donors and electron acceptors
for ATP synthesis Picture Slides: Fig. 27.13 & Table 27.4)
(1)
Use light
(2)
Organic compounds
(3)
Inorganic compounds
Picture Slides: Methane Seep Organisms in the Gulf of Mexico form symbiotic
associations with methanotrophic bacteria; From McDonald & Fisher, National
Geographic 1996, 190(4); 95 (Figures not in text)
G.
Key Lingeages
1. Spirochaeles Bacteria Picture Slide: Fig. 27.16
a. Corkscrew shape
b. Syphilis and Lyme disease are caused by spirochetes
2. Chlamydiales Picture Slides Fig. 27.17
a. All species are endosymbionts and live in hosts
b. Chlamydia trachomatis infections cause blindness and urogenital
infections if passed via intercourse.
3. High-GC Gram positives Picture Slide: Fig. 27.18
a. DNA with a high guanine and cytosine content.
b. Over 500 antibiotics have been isolated from species in genus
Streptomyces.
c. Tuberculosis and leprosy are caused by species from this group.
d. Species in this group live in plant roots and fix nitrogen.
4. Cyanobacteria Picture Slide: Fig. 27.19
a. All perform oxygenic photosynthesis.
b. Some can fix nitrogen.
c. Produce much of the oxygen and nitrogen that other species need.
d.
A few species live with fungi, forming lichens.
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