Biology

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Prokaryotes

16.1-16.10
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Phylogenic Tree of the Three Domains
Prokaryote Bacteria Archaea
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Prokaryotes Archaea

• Ancient
• Exist in harsh habitats early Earth
• Extremophiles
• Thermophiles hot springs/ volcanic vent
• Halophiles salty bodies of water
• Methanogens anaerobic mud give off methane
  swamp gas

Similar to Bacteria small size lack most
organelles no true nucleus
Similar to Eukaryotes similar DNA sequences for
ribosomes enzymes junk or intron DNA
sequences (dont code for protein) dont respond
to antibiotics (cell wall is different from proks)
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Prokaryotes Early Bacteria Forms

• Stromatolites cyanobacteria that grow in mats on
  rock-like mounds in shallow reefs dominate
  oceans(3 bya)
• Cyanobacteria - Early aerobic bacteria
  oxygenate Earth cause mass extinction game
  changer (oxygen atmosphere 2.5 bya)

http//www.bbc.co.uk/science/earth/earth_timeline/
first_life
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The Oxygen Revolution

• 2.4 bya
• Evolution of photosynthetic cyanobacteria( 3
  bya) --gt free oxygen in oceans, lakes the
  atmosphere
• O2 toxic to most existing organisms --gt Mass
  Extinction
• Stimulates evolution of aerobic organisms
  (requiring oxygen)
• Some forms of anaerobic bacteria (no or low O2)
  still survive (muddy lake bottoms/swamps)

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Bacteria Pathogens

• Pathogens disease causing bacteria
• How?
• Secrete protein exotoxins (poisons)
• Clostridium toxin --gt muscle spasms/lockjaw(tetanu
  s)
• S. Aureus --gt multiple toxins (necrotizing
  tissue vomiting, diarrhea, fever)
• E. Coli --gt food poisons

• 2. Endotoxins fragments of outer membrane act
  toxins fever, aches, drop in blood pressure
• Meningitis - swelling of brain membranes
• Salmonella - food poisoning typhoid
• List of bacterial infections
• http//classes.midlandstech.edu/carterp/Courses/bi
  o225/InfectiousDiseases_all_print.htm

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Bacteria Pathogens (Bioweapons)

• Anthrax live in soil (farms) skin infection
  not harmful inhaled deadly
• Y. pestis (Plague) bubonic (black death)
  pneumonic (disintegrates lungs)
• Clostridium botulinum 7 toxins
• Food poisoning
• Deadliest blocks nerve transmission stops
  muscle contractions (breathing)
• Diluted in botox - relax facial muscles

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MRSA Methicillin-resistant Staph. AureusHard
to treat staph infectionResistant to most
antibioticsCommonly starts as a skin infection
(lesion/wound)Harmful in elderly nursing home
hospitals (weakened immune systems)
Superbugs http//www.sosq.vcu.edu/videos.aspx NY
Hostpitals Superbugs cbs news
http//www.cbsnews.com/videos/cre-superbug-cases-f
ound-in-at-least-43-states/ Antibiotics in animal
feed http//www.cbsnews.com/videos/fda-to-roll-b
ack-use-of-antibiotics-in-beef-pork-and-poultry/
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Bacterial Meningitis
http//www.huffingtonpost.com/2013/12/05/meningiti
s-princeton-uc-santa-barbara-infection-bacterial_n
_4392509.html?utm_hp_refcollegeirCollege http/
/www.nbcnews.com/health/princeton-agrees-meningiti
s-vaccine-fight-outbreak-2D11616706
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Beneficial Uses of Bacteria

• Medicine/Pharmaceutic
• Produce desired gene products (insulin)
• Food Cheese Yogurt
• Aid Digestion (probiotics)
• Make vitamin K in intestines
• Break down cellulose in termite guts

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Beneficial Uses of Bacteria

• Chemical recycling
• Decomposers replenish soil nutrients and
  release CO2 back to the atmosphere
• N.-fixing bacteria convert nitrogen gas in the
  atmosphere to an organic form usable by plants
  grow on roots of beans, nuts, clover
• Bioremediation
• Sewage treatment decompose organic matter in
  sewage sludge
• Oil spill clean-up genetically modified digest
  oil
• Clean old mining sites detoxify by extracting
  lead mercury,arsenic

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Bacteria Shape

• Cocci spherical
• Bacilli rod-shaped
• Spirilla spiral shaped

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Structure Function of Bacteria Cell Wall

• Gram (stain) purple thick layer of
  peptidoglycan retains dye
• Gram( ) pink stain thin layer of peptidglycan
  with outer membrane

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Structure Function of Bacteria Motility

• Flagellum
• Pilli
• Slime secretion

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Bacterial Repro. Binary Fission

• DNA copied moved to opposite ends of cell as
  the cell divides occurs almost continuously
  ASEXUAL

• Rapid 20 min.
• Parents Offspring genetically identical

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Plasmids

• Loops of DNA found in some bacteria can
  integrate into chromosome be translated into
  proteins
• Can be shared b/w bacteria
• R plasmids carry genes for antibiotic
  resistance

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Genetic Variation Sharing Genes

• 1. Conjugation 2 bacteria join thru. temporary
  bridge and exchange plasmids.
• Can be b/w diff. species

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Genetic Variation Sharing Genes

• Transformation
• incorporates DNA fragments (fr. dead bacteria) in
  surroundings into genome.

• 3. Transduction
• Bacteriophage (virus that infects bacteria)
  inject fragment of DNA from previous host along
  w/ viral DNA

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Original Source of Variation Mutation

• any alteration of nucleotide sequence
• Usually results in malfunction/cell death
• Occasionally translates into new beneficial
  trait! (antibiotic resistance)

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Endospores

• Allow bacteria to survive harsh conditions go
  into a dormant endospore form
• DNA copied one copy surrounded by a thick
  protective coat outer cell disintegrates
• When conditions are favorable, endospores absorb
  water grow again. Ex anthrax

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Modes of Nutrition
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Viruses Bacteriophage The Boundary of Life

• All living things share 8 characteristics.
  Viruses do not meet all of these characteristics.
  
• Attack eukaryotic cells Bacteriophages attack
  prokaryotic cells.
• Capable of reproducing at a very rapid rate, but
  only in host cell.
• Responsible for many diseases
• Found everywhere.

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Viral Structure

• Protein coat (capsid) surrounds viral DNA or RNA

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Viral Structure Variations
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Viruses Disease

• Method of causing disease is very different from
  that of bacteria (different treatment
  prevention methods too)
• Antibiotics will not work on viruses because they
  target specific enzymes not found in viruses or
  host cells
• Some examples of viral diseases include
• Influenza (RNA) Polio (RNA)
• Common cold(RNA) Hepatitis (DNA)
• Measles (RNA) Herpes (DNA)
• Mumps (RNA) Smallpox (DNA)
• AIDS (RNA) Rabies (RNA)

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Viral Infection

• Invade cells use the host cell's machinery to
  synthesize own macromolecules.
• Reproduce in 2 ways
• 1. Lytic cycle destroying the host cell during
  reproduction.
• 2. Lysogenic Cycle a parasitic type of
  partnership with the cell

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Lytic Cycle Lysogenic Cycle
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Viruses are host specific a protein on the
surface of the virus has a shape that matches a
molecule in the plasma membrane of its host,
allowing the virus to lock onto the host cell.
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Proviruses

• DNA virus that has been inserted into a host
  cell chromosome.

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Retroviruses HIV

• Retroviruses reverse the normal DNA to RNA to
  protein flow
• RNA viruses RNA ? DNA ? protein
• Reverse transcriptase catalyzes synthesis of DNA
  fr. RNA template
• DNA intermingles w/ host DNA as a provirus making
  it difficult to detect

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Prions

• Proteins that cause several diseases of the
  brain Mad cow disease, Kuro, Creutzfeldt-Jacob
  disease (CJD) Scrapie (in sheep)
• Only infectious agent that do not contain genetic
  material
• Normal form play important roles in helping brain
  function (nerve cells communication)
• Abnormal prions destroy the brain
• Three ways to acquire abnormal prions
• Infection with abnormal prions
• Inherited genes that give rise to abnormal prions
• Spontaneous genetic mutations that give rise to
  abnormal prions

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Viroids

• Small strands of RNA rather than strands of
  protein.
• Smaller than the strands of genetic info in
  viruses and contain no protein coat.
• Replicated using host cell machinery, like
  viruses
• Cause plant diseases potato spindle tuber,
  avocado sunblotch, chrysanthemum stunt, and
  chrysanthemum chlorotic mottle

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Immune Response
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VACCINES Defense Against Viral Diseases
Vaccines immunizations Made from weakened
(attenuated) bacteria/viruses or parts (anitgens/
fragments) of bacteria/viruses Antigens of
pathogen elicit immune response without you
getting sick.
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• HIV doesnt target just any cell, it goes right
  for the cells that want to kill it. Helper" T
  cells are HIV's primary target. These cells help
  direct the immune system's response to various
  pathogens.

HIV is an RNA retro-virus that targets helper T
cells. Helper T cells deplete immune response
is compromised. The virus can infect 10 billion
cells a day, yet only about 1.8 billion can be
replaced daily.
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From HIV to AIDS

• During first few years (7-10) after HIV
  infection, person is usually asymptomatic.
• During the symptomatic phase, the body has
  insufficient numbers of T-Cells (from normal
  800-1200 /mm3 to 200/ mm3 ) to mount an immune
  response against infections.
• Chronic diarrhea, minor mouth infections, night
  sweats, headache fatigue are common
• At the point when the body is unable to fight off
  infections, a person is said to have the disease
  AIDS. (Generally when count drops below 200 /mm3
  )
• It is not the virus or the disease that
  ultimately kills a person it is the inability to
  fight off something as minor as the common cold.

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AIDS The Global Epidemic

• Around 2.6 million people became infected with
  HIV in 2009.
• Sub-Saharan Africa has been the hardest hit by
  the epidemic. In 2009 over two-thirds of AIDS
  deaths were in this region