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http://ludwig.lajuntaschools.org/science/Learn_Share/Entries/2009/10/12_AP_Biology__What_Are_Prokaryotes_files/shapeimage_2.png
• Structure of a Prokaryotic Cell
• Classification of Prokaryotes
• Identifying Prokaryotes
• Bacterial Nutrition: Obtaining Energy
• Bacterial Metabolism: Using Energy
• Bacterial Growth & Reproduction
• Significance of Prokaryotes
PROKARYOTES
http://s689.photobucket.com/albums/vv258/Moodle_Pics/?action=view¤t=PROEUVENN.jpg&newest=1
.2-10
Small size, big impact! • Black Death (bubonic plague)
• Prokaryotes as decomposers “If prokaryotic decomposers were to disappear, the chemical cycles that sustain life would halt, and all forms of eukaryotic life would also be doomed. In contrast, prokaryotic life would undoubtedly persist in the absence of eukaryotes, as it once did [for about 1.5 B years when they first appeared 3.5 B years ago.]”
http://alchemipedia.blogspot.com/2009/09/plague-of-florence-1348-etching.html,
http://www.kimayahealthcare.com/Upload/AllImages/I_6_193_10_3191.jpg
Structure of a
Prokaryotic Cell
http://micro.magnet.fsu.edu/cells/procaryotes/images/procaryote.jpg
• Contributes to pathogenicity
• Site of antibiotic action
Cell wall
• May contain pigments & enzymes for photosynthesis
Cell membrane
• W/o cytoskeleton, cytoplasmic streaming
Cytoplasm
Nucleoid region
Ribosomes
• Lacks microtubules
Flagellum
• Shorter, thinner than flagella
Pili (sing. Pilus)
Classification of prokaryotes
Domain Bacteria
• peptidoglycan cell walls
• more members than
Archaea
• Ex. Streptococcus, E.
coli, cyanobacteria
Domain Archaea
• no peptidoglycan in CWs
• w/ some DNA /RNA sequences more similar to those of eukaryotes than those of bacteria
• many are extremophiles
• Examples
• Methanogens
• Halophiles
• Thermophiles
• Acidophiles
http://en.wikipedia.org/wiki/Peptidoglycan
https://meyerbio1b.wikispaces.com/file/view/archaebacteria_vs_
eubacteria.png/58172168/archaebacteria_vs_eubacteria.png
http://upload.wikimedia.org/wikipedia/commons/thumb/f/f5/Grand_prismatic_spring.jpg/2
50px-Grand_prismatic_spring.jpg
Identifying Prokaryotes Cell Shape
• Three basic shapes:
• Bacilli (sing. bacillus)
• Cocci (sing. coccus)
• Spirilla (sing. spirillum)
• Cell arrangement:
• diplo-
• staphylo-
• strepto-
http://www.ibri.org/RRs/RR051/51bacterialshapes-Merc.gif
Identifying Prokaryotes Cell Wall Gram staining
• two dyes • crystal violet (purple)
• Safranin (red)
• two results • Gram-positive (purple, thicker
peptidoglycan layer)
• Gram-negative (red or pink, thinner peptidoglycan layer)
http://biofilmbook.hypertextbookshop.com/v003/r002/artifacts/images/labExercises/stain_diagram.jpg,
http://en.wikipedia.org/wiki/File:Gram_stain_01.jpg
Identifying Prokaryotes Movement
• Flagella
• Gliding on layer of
slimelike material
w/c they produce
• Nonmotile
http://www.nature.com/nrmicro/journal/v8/n9/fig_tab/nrmicro2405_F1.html
Bacterial Nutrition: Obtaining Energy
• Autotroph (“self-feeder”): can produce own food
• Heterotroph (“other feeder”): obtains energy from food (organic compounds) it consumes
• Phototroph: obtains energy from sun
• Chemotroph: obtains energy from inorganic compounds
Diverse adaptations allow prokaryotes to live in
nearly every environment imaginable!
Bacterial Metabolism: Using Energy
• Cellular respiration vs. fermentation
• Strict/obligate aerobes
• Facultative anaerobes
• Strict/obligate anaerobes
http://www.slic2.wsu.edu:82/hurlbert/micro101/images/hist24.gif
Bacterial Growth &
Reproduction
• Asexual reproduction
through binary fission
• No exchange or recombination
of genetic information
https://encrypted-
tbn3.gstatic.com/images?q=tbn:ANd9GcSFNiJzU9qun26Xp1JH18swIVYv8lpVzv2IKig
qcAEftjQ9di8MbA
Bacterial Growth &
Reproduction
Means of genetic recombination:
• Conjugation • Donor transfers genetic
information to recipient through sex pilus
• Transduction • Bacterial DNA is moved
from one bacterium to another by a virus
• Transformation • Bacteria takes up naked
DNA from the environment
http://upload.wikimedia.org/wikipedia/commons/thumb/3/3e/Conjugation.svg/350px-Conjugation.svg.png,
http://www.pc.maricopa.edu/Biology/rcotter/BIO%20205/LessonBuilders/Chapter%209%20LB/Ch9b_print.html
Bacterial Growth & Reproduction
Spore formation • endospore
• thick internal wall encloses DNA and a portion of the cytoplasm
• bacterium to survives harsh conditions that would otherwise kill it
Importance of
Prokaryotes
• Evolution of life on earth
• Nutrient cycles
• Pathogens
• Medicines
• Symbiotic organisms
• Genetic engineering
• Bioremediation
• Food spoilage http://world.edu/wp-content/uploads/2011/12/cyanobacteria1.jpg,
http://upload.wikimedia.org/wikipedia/commons/thumb/f/fe/Nitrogen_Cycle.svg/320px-
Nitrogen_Cycle.svg.png, http://thehealthyapron.com/wp-
content/uploads/2011/02/Yogurt.jpg, http://en.wikipedia.org/wiki/File:Streptomycin-
1ntb-xtal-3D-balls.png, http://prod.biologybiozine.com/wp-
content/uploads/2011/09/beachCleanup.jpg,
http://en.wikipedia.org/wiki/File:Staphylococcus_aureus_VISA_2.jpg,
http://www.scq.ubc.ca/wp-content/GMcrop.gif