Transcript Prokaryotes - Falmouth Schools

Prokaryotes
Chapter 27
Quic kTime™ and a
dec ompres sor
are needed to see this pic ture.
• Earliest organisms on Earth - evolved
alone for 1.5 billion years.
• More prokaryotes inhabit a handful of
fertile soil or the mouth or skin of a
human than the total number of people
who have ever lived.
QuickTime™ and a
decompressor
are needed to see t his picture.
The vivid reds, oranges, and
yellows that paint these rocks
are colonies of prokaryotes.
• Types of diseases caused by
bacteria - tuberculosis, cholera,
many sexually transmissible
diseases, certain types of food
poisoning.
QuickTime™ and a
d eco mpres sor
are nee ded to s ee this picture.
http://news.bbc.co.uk/olmedia/1825000/images/_1827130_tb_bacterium300.jpg
QuickTime™ and a
decompressor
are needed to see this picture.
TB Bacteria
• Most bacteria benign or
beneficial.
• Bacteria in intestines produce
vitamins.
• Prokaryotes recycle carbon,
other elements between soil
and atmosphere.
QuickTime™ and a
decompressor
are needed to see this picture.
QuickTime™ and a
decompressor
are needed to see this picture.
• Mitochondria, chloroplasts evolved
from prokaryotes - became
residents in host cells.
QuickTime™ and a
decompressor
are needed to see this picture.
http://www.botany.hawaii.edu/faculty/webb/Bot201/Hornworts/AnthEpiSurfCplast.jpg
http://www.botany.hawaii.edu/faculty/webb/Bot201/Hornworts/AnthEpiSurfCplast.jpg
QuickTime™ and a
decompressor
are needed to see this picture.
• 2 prokaryotic domains (above
kingdom): Bacteria and Archaea
• Archaea inhabit extreme
environments - differ from bacteria
in structural, biochemical, and
physiological characteristics.
QuickTime™ and a
decompressor
are needed to see t his picture.
QuickTime™ and a
GIF decompressor
are needed to see this picture.
• Most prokaryotes - unicellular.
• Some aggregate for period of time
or form colonies.
• Shapes - spheres (cocci), rods
(bacilli), helices (spirochetes).
QuickTi me™ a nd a
de com press or
are need ed to se e th is p icture.
• Cell wall maintains shape, physical
protection, prevents cell from
bursting.
• Most bacterial cell walls contain
peptidoglycan, (polymer of sugars
and polypeptides)
• Archaea lack peptidoglycan.
Quic kTime™ and a
dec ompres sor
are needed to see this pic ture.
http://msnbcmedia3.msn.com/j/msnbc/Components/Photos/050207/050207_livesci_extremophiles_hmed11a.hlarge.jpg
QuickTime™ and a
decompressor
are needed to see this picture.
• Gram stain - identifies bacteria
based on differences in cell walls.
• Gram + have simpler cell walls,
large amounts of peptidoglycans.
QuickTime™ and a
d eco mpres sor
are nee ded to s ee this picture.
• Gram - have more complex cell
walls, less peptidoglycan - outer
membrane contains carbohydrates
bonded to lipids.
• More threatening than grampositive species.
QuickTi me™ a nd a
de com press or
are need ed to se e th is p icture.
• Gram-negative bacteria more
resistant to antibiotics - outer
membrane impedes entry of
antibiotics.
Quic kTime™ and a
dec ompres sor
are needed to see this pic ture.
http://jon9783.myweb.uga.edu/image/image1.jpg
E. coli
QuickTime™ and a
decompressor
are needed to see this picture.
• Many prokaryotes secrete sticky
protective layer - capsule.
• Glue together cells of prokaryotes
that live as colonies.
Quic kTime™ and a
dec ompres sor
are needed to see this pic ture.
http://www.olympusmicro.com/micd/galleries/darkfield/bacterialcapsules.html
QuickTime™ and a
decompressor
are needed to see this picture.
• Pili fastens pathogenic bacteria to
mucous membranes of host.
• Some specialized for holding 2
prokaryote cells together to transfer
DNA during conjugation.
QuickTime™ and a
decompressor
are needed to see t his picture.
• Most common form of movement flagella.
• 2nd found in spirochetes - filaments
- moves like a corkscrew.
• 3rd occurs in cells that secrete slimy
threads - glides along at growing
end of threads.
QuickTi me™ and a
decompressor
are needed to see thi s pi ctur e.
• Capable of taxis (chemotaxis,
phototaxis)
QuickTi me™ a nd a
de com press or
are need ed to se e th is p icture.
http://www.brineshrimpdirect.com/contentimages/brineshrimp_photo3.jpg
QuickTime™ and a
decompressor
are needed to see this picture.
• Prokaryotic cells lack nucleus,
internal compartments bounded by
membranes like eukaryotes.
• Use infolded regions of plasma
membrane to perform metabolic
functions (cellular respiration,
photosynthesis)
Quic kTime™ and a
dec ompres sor
are needed to see this pic ture.
• Simpler genomes than eukaryotes DNA concentrated as fibers in
nucleoid region.
• Single prokaryotic chromosome double-stranded DNA molecule in
form of ring.
• May also have smaller rings of DNA
(plasmids) consist of only a few
genes.
Qui ckTime™ and a
decompressor
are needed to see thi s pi cture.
http://student.biology.arizona.edu/honors2000/group10/
plasmid.gif
QuickTime™ and a
decompressor
are needed to see this picture.
• Prokaryotes reproduce asexually binary fission.
• Transformation - cell can absorb,
integrate fragments of DNA from
environment.
• Conjugation - directly transfers genes
to another cell.
• Transduction - viruses transfer genes
between prokaryotes.
QuickTime™ and a
decompressor
are needed to see t his picture.
• Prokaryote can withstand harsh
conditions.
• Bacteria form resistant cells endospores - cell replicates
chromosome, surrounds one
chromosome with durable wall.
• Can survive lack of nutrients and
water, extreme heat or cold, and
most poisons.
QuickTime™ and a
dec ompres sor
are needed to s ee this pic ture.
http://www.apsnet.org/education/illustratedglossary/PhotosE-H/endospore.jpg
QuickTime™ and a
decompressor
are needed to see this picture.
• When conditions favorable hydrates and becomes active.
• Microorganisms release antibiotics
to inhibit growth of other
microorganisms (prokaryotes,
protists, and fungi) because of
competition for space.
• Humans use these to kill bacteria.
Quic kTime™ and a
dec ompres sor
are needed to see this pic ture.
http://www.lausd.k12.ca.us/Figueroa_EL/images/Mystery%20to%20Medicine/antibiotics.jpg
QuickTime™ and a
decompressor
are needed to see this picture.
• Prokaryotes grouped according to
how they obtain nutrition.
• 1Light energy - phototrophs.
• 2Energy from chemicals in
environment -chemotrophs.
• 3Need only CO2 as carbon source autotrophs.
• 4Require organic nutrient as carbon
source - heterotrophs.
QuickTime™ and a
d eco mpres sor
are nee ded to s ee this picture.
http://www.clcbio.com/scienceimages/cyanobacteria.png
QuickTime™ and a
decompressor
are needed to see this picture.
• Further divided based on what they
use.
• 1Photoautotrophs - photosynthetic light energy to synthesize organic
compounds from CO2.
• Photoautotrophic prokaryotes cyanobacteria.
• Photosynthetic eukaryotes - plants
and algae.
QuickTime™ and a
d eco mpres sor
are nee ded to s ee this picture.
http://www.astrographics.com/GalleryPrints/Display/GP
2028.jpg
QuickTime™ and a
decompressor
are needed to see this picture.
• 2Chemoautotrophs need CO2 as
carbon source, obtain energy by
oxidizing inorganic substances, not
light - i.e. hydrogen sulfide (H2S),
ammonia (NH3)
• Unique to prokaryotes.
• 3Photoheterotrophs - light to generate
ATP, obtain carbon in organic form.
• Restricted to prokaryotes.
Quic kTime™ and a
dec ompres sor
are needed to see this pic ture.
http://www.theguardians.com/Microbiology/lyngb3_bg.jpg
QuickTime™ and a
d eco mpres sor
are nee ded to s ee this picture.
• 4Chemoheterotrophs must consume
organic molecules for energy and
carbon.
• Found in prokaryotes, protists, fungi,
animals, and even some parasitic
plants.
• Majority of prokaryotes chemoheterotrophs.
• Include saprobes (decomposers) and
parasites.
QuickTime™ and a
dec ompres sor
are needed to s ee this pic ture.
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings
• O2 also has impact.
• Obligate aerobes require O2 for
respiration.
• Facultative anerobes will use O2 if
present; can also grow by
fermentation in anaerobic
environment.
• Obligate anaerobes are poisoned
by O2 use either fermentation or
anaerobic respiration.
QuickTi me™ a nd a
de com press or
are need ed to se e th is p icture.
QuickTime™ and a
decompressor
are needed to see this picture.
http://www.medschool.lsuhsc.edu/microbiology/DMIP/cpgs.jpg
• 1st prokaryotes - heterotrophic - fed on
primordial soup - depleted supply of
organic molecules in environment.
• Natural selection favored prokaryote
that could harness energy of sunlight
make ATP.
• Photosynthesis probably evolved once
and was lost by heterotrophs.
QuickTime™ and a
d eco mpres sor
are nee ded to s ee this picture.
http://www.multihostingservice.co.uk/teamanarchy/simo
n/images/Sporesom4.jpg
QuickTime™ and a
decompressor
are needed to see this picture.
• Atmosphere transformed from
reducing one to oxidizing one by
evolution of cyanobacteria.
• Cellular respiration probably
evolved by modification of
photosynthetic equipment for new
function (both use electron
transport chain).
Quic kTime™ and a
dec ompres sor
are needed to see this pic ture.
http://www.mfe.govt.nz/publications/ser/snapshot-lakewater-quality-nov06/html/images/cyanobacteria.jpg
QuickTime™ and a
decompressor
are needed to see this picture.
Survey of Prokaryotes
• Archaea - extremophiles, “lovers” of
extreme environments.
• 1Methanogens - obtain energy by using
CO2 to oxidize H2 replacing methane as
waste - live in swamps and marshes,
guts of animals.
• May contribute to global warming.
QuickTime™ and a
decompressor
are needed to see t his picture.
http://genome.jgi-psf.org/finished_microbes/images/metba.gif
QuickTime™ and a
decompressor
are needed to see this picture.
• 2Extreme halophiles - saline places
- Great Salt Lake, Dead Sea.
• Colonies form purple-red scum
from photosynthetic pigment similar
to pigment found in human retina.
QuickTime™ and a
decompressor
are needed to see this picture.
• 3Extreme thermophiles - hot
environments - optimum
temperatures for most - 60oC-80oC.
• One sulfur-metabolizing thermophile
lives at 105oC water near deep-sea
hydrothermal vents.
Quic kTime™ and a
dec ompres sor
are needed to see this pic ture.
http://www.ls.toyaku.ac.jp/~lcb-7/images/hydrothermalvent.jpg
QuickTime™ and a
decompressor
are needed to see this picture.
Why important?
QuickTi me™ and a
decompressor
are needed to see thi s pi ctur e.
• Decomposers - important to
nutrient recycling.
• Nitrogen fixation - important to
nitrogen cycle.
• Many - symbiotic - involved in
mutual relationship with host - i.e. fish provides bioluminescent
bacteria under eye with
organic materials uses flashlight to
lure prey, signal potential mates.
• Most of the time our defenses
check growth of pathogens.
• Pathogenic prokaryotes cause half
of all human disease when internal
defenses cannot fight them off.
Quic kTime™ and a
dec ompres sor
are needed to see this pic ture.
• Some pathogens - opportunistic
(always in our system) - attack only
when defenses down.
• Robert Koch 1st to connect certain
diseases to specific bacteria established Koch’s postulates.
• Ensures that pathogen really is
causing the disease.
QuickTime™ and a
decompressor
are needed to see this picture.
http://upload.wikimedia.org/wikipedia/commons/thumb/6
/67/Escherichia_Coli_NIAID.jpg/180pxEscherichia_Coli_NIAID.jpg
QuickTime™ and a
decompressor
are needed to see this picture.
• Pathogens can cause illness by
producing poisons - exotoxins and
endotoxins.
• Exotoxins are proteins secreted by
prokaryotes - can produce disease
symptoms even if prokaryote not
present.
• Endotoxins - components of outer
membranes of some gram-negative
bacteria.
• Common in food poisoning.
QuickTime™ and a
dec ompres sor
are needed to s ee this pic ture.
• Disease control mostly due to
education, not to expansion of
drugs.
• Overuse of antibiotics has led to
evolution of new strains of bacteria.
• Biological warfare also still a threat.
• Humans use prokaryotes to treat
biological issues, such as oil spills.
QuickTi me™ a nd a
de com press or
are need ed to se e th is p icture.