Transcript Ch 26-27 powerpoint

Green sea turtle
Olive Ridley sea turtle
Say AH!
Tuberculosis
Ch.27
The Prokaryotic
World
Bacteria
http://video.google.com/videosearch?
q=bacteria&hl=en&sitesearch= (3)
See Table 27.2
They are everywhere.
From what we know, they originated 3.5
billion years ago
And they were alone on earth for 2
billion years!
Prolific and Ubiquitous
Their Importance?
Environmentally, agriculturally, medically, evolutionarily, etc
Shapes
Ecological Impacts of
Prokaryotes
Recycle (Decomposers)
Symbiosis:
Mutualism (+ / +)
 Commensalism (+ / o)
 Parasitism (+ / -)

Mutualism ex: legumes… N2 fixation
Nitrogen fixing legume
root nodules
N cycle (mainly proteins)
See p. 763!
Penicillin mold
Penicillin: the First Miracle Drug
Alexander Fleming, a Scottish scientist, is
credited with discovering the first antibiotic,
penicillin. In 1928, he noticed that bacteria
could not survive on a plate that contained a
mold commonly found on bread. He went on
to show that the effect was due to a
diffusible substance made by the mold.
However, penicillin was not available to the
general public until the early 1940s when
scientists learned how to produce and purify
large amounts of penicillin.
How do antibiotics work?
Two ways…
 Hint: think of ways to kill or hinder
prokaryotic development without hurting
our own Eukaryotic cells…

Gram -
Gram +
Why are gram
negative
usually more
threatening
than
gram +?
Like Fig 27.3
What are
endotoxins vs
exotoxins?
http://www.hhmi.org/biointeractive/disease/animation
s.html animation of E. coli infecting intestinal cells
Bacteria
http://video.google.com/videosearch?q=bacteria&hl=
en&sitesearch= (3)
Endosymbiosis
http://video.google.com/videosearch?q=endosymbioti
c+theory&sitesearch= (1)
How can Photosynthetic bacteria exist
and function?
What were the early bacteria on earth
like? Why?
When did respiration evolve? Why?
Ch 26
Endosymbiotic Theory
Endosymbiosis
http://video.google.com/videosearch?q=endosymbiotic+theory&sitesearch=
Ch 26
THE ATMOSPHERE’S EVOLUTION
1. Early atmosphere: no O2, obligate
anaerobes, chemoautotrophs
2. Origin of photosynthesis: harmful UV,
use sun’s E. to fix carbon or to create H+
gradient
3. Oxygen revolution: H2O used as an esource to reduce CO2, O2 is released
Iron oxides found…
4. Adaptations to the O2 rich atmosphere
Ch 26
Urey/Miller experiments:
Lab conditions =
H20, H2, CH4, NH3 (reducing
atmosphere)
results:
various Amino Acids
Sugars
Lipids
Purine/pyrimidine bases
Extinctions… Permean (~250 mya) and
Cretaceous (~65 mya)
** Survivors of extinctions became
stock for new radiations that filled
many of the adaptive zones vacated
or newly created by extinctions. **
Pangaea (250 million years ago) to present day
http://video.google.com/videosearch?q=pangaea&hl=en&sitesearch=
Figure 26.22
p. 530…
So now… again why the 3 domian
system?
This figure is a peek into the first half of
semester 2!!
Disease: Koch’s Postulates
1. Find pathogen
2. Isolate it, grow it
3. Infect experimental animals
4. Re-isolate the same pathogen from
the infected animal
Exotoxins: secreted
Endotoxins: on outer membranes
Identification of different species:
Important early science
Shapes: Coccus, bacilli, spirilli =helices
Cell walls made of: Peptidoglycan
Gram staining: + purple / - pink
The gram+ bacteria are purple, their outer
walls are Peptidoglycan (page 505)
 Which type is typically more dangerous to
humans? Why?
 How is this important?

Other characteristics
Antibiotics: how do most work? __2 ways?__
Prokaryote Attachment: Pili, capsule
Movement:
100x their body length per second! Us:1mile /9.3sec
 Flagella (one or many)
 Spirochetes
 Slimy chemicals to glide on (yum!)

Taxis: chemotaxis, phototaxis, magnetic,
gravity
Reproduction and Genetic
Recombination
Binary fission (cloning)
No mitosis or meiosis occurs
 Bacteria in a bottle simulation

Transformation:

genes taken up from environment
Conjugation:

genes transferred directly from one prokaryote to
another
Transduction: transfer of genes to prokaryotes
from viruses
Structural Comparisons with
Eukaryotes
No nucleus
Very little compartmentalization
Nucleoid region, One circular chromosome,
some have plasmids (which are self replicating
DNA rings)
Smaller genomes, little protein w/DNA
Ribosomes: selective antibiotics
Endospores
Some can make their own antibiotics
Then how do prokaryotes
acquire their
genetic variations?
MUTATIONS !!
reproduction rates for starting a new
generation can be measured in minutes
or hours = many mutations may
accumulate in a short period of time.
MATH CHALLENGE
If Prokaryotes reproduce every 2 hours
and we every 15 years (historically
based average), and prokaryotes have
been around for 3.5+ billion years and
we have been around 200,000 years,
how much more developed and adapted
are prokaryotes than humans?
Nutrition
Energy source: Photo. / Chemo.
Carbon source: autotroph / heterotroph
Examples: photoautotroph …etc…
Saprobes (saprotrophs)-absorb
Parasites
Nitrogen fixation
Oxygen
Obligate aerobes = have to have O2
Obligate Anaerobes = have to be in an
environment free of O2
Facultative = can use O2 or not
Ex: facultative anaerobe
obligate aerobes
“A mite makes the sea roar!”
Feynman
A prokaryote mite transformed (and is
transforming) the earth’s entire atmosphere.
EARLY METABOLISM:
ATP, glycolysis, fermentation (none of these
need oxygen)
All are common to most all living organisms,
implies an early origin in time
Systematics, Classification
3 domains: A, B, E
Why are they in different domains?
What are some different characteristics
of Archaea and Bacteria?
Methanogens, extreme halophiles,
extreme thermophiles