Microbiology

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Microbiology

• Bacteria and Viruses

Skip to last slide to see which sections in the
book are covered in this unit!
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Introduction to Prokaryotes

• Extremely small, but found wherever there is life
• Can live in extreme environments
• Harmful (diseases) and helpful (antibiotics)
• Would not be able to survive without them
• Decomposers
• Recycle nutrients
• Very diverse

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Louis Pasteur

• Considered father of microbiology
• Discovered process of pasteurization
• Germ Theory ? said that
  disease was spread by
  germs and tried to improve
  hospitals by raising
  standards

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• Do NOT copy, just read
• Louis Pasteur's main contributions to
  microbiology and medicine were instituting
  changes in hospital/medical practices to minimize
  the spread of disease by microbes or germs,
  discovering that weak forms of disease could be
  used as an immunization against stronger forms
  and that rabies was transmitted by viruses too
  small to be seen under the microscopes of the
  time, introducing the medical world to the
  concept of viruses.

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Division of Prokaryotes

• There are two main groups of prokaryotes
• Bacteria vs. Archaea

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Structure of Prokaryotes

• Single-celled
• Cell membrane
• Most have a cell wall Made of peptidoglycan
• Cell wall is covered by a capsule
• Sticky layer of proteins or polysaccharides that
  helps with attachment
• Pili ? hairlike appendages that help with
  attachment
  ex. Sex pili (more later)

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Internal structure

• Nucleoid region ? DNA organized in a circular
  chromosome
• Plasmid ? carry extra genes can be transferred
  to other bacteria ex. Resistance to antibiotics
• Ribosomes
• No mitochondria or chloroplasts, but have
  infoldings of membranes so that they can carry
  out respiration and some can do photosynthesis

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Prokaryote Shape

• Three general shapes ?
• Cocci (spherical)
• Bacilli (rod shaped)
• Spirilla or spirochetes (curved or spiral)
• Staphlo clusters
• Strepto chains

Spirochete ?
Cocci ?
Bacilli
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Prokaryotic Movement

• Use flagella
• Different from eukaryotic flagella
• Not made up of
  microtubules naked
  protein structure
• Doesnt wave, it does
  propeller-like rotations

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Oxygen Needs

• Obligate aerobes ? must be in oxygen
• Obligate anaerobes ? cannot be in oxygen
• Facultative anaerobes ? can survive with or
  without oxygen

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Prokaryotic Reproduction

• Can reproduce quickly in favorable conditions
• Usually about 1-3 hours, some up to every 20
  minutes
• Asexual Reproduction binary fission
• Creates two identical cells

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Sexual Reproduction

• Increases diversity 3 ways
• Transformation ? take up foreign DNA from
  surrounding environment
• Transduction ? transfer of bacteria cells by a
  phage
• - phage virus that infects bacteria
• 3. Conjugation ? when 2 bacterial cells mate
  DNA is exchanged through sex pili

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Transduction
Transformation
Conjugation
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Endospores

• Endospore ? self preservation thick-coated,
  protective cell produced inside a bacteria during
  harsh conditions dehydrates and becomes dormant
• Can survive all types of trauma and can last for
  hundreds of years
• When conditions
• improve, it absorbs
• water and resumes growth

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Prokaryotic Nourishment

• modes of nutrition ? how organisms get two
  major resources carbon and energy
• Autotrophs producers
• Heterotrophs consumers

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Prokaryotic Groupings

• Extreme halophiles ? salt lovers Great Salt Lake
• Extreme thermophiles ? heat lovers thrive in
  high temps or very acidic environments
• Methanogens ? live in anaerobic environments
  give off methane as waste product abundant in
  digestive systems help break down
  cellulose

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Gram Staining

• Another technique to group bacteria
• Gram positive bacteria ?
• Simpler cell walls with a thicker layer of
  peptidoglycan
• Gram negative bacteria ?
• More complex cell walls less peptidoglycan with
  an outer membrane that contains lipids bonded to
  carbs
• Usually more threatening than gram because
  lipids are often toxic

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Harmful Bacteria

• Pathogenic bacteria cause about half of all human
  diseases
• Exotoxins ? a poison secreted by bacterial cells
  can cause deadly diseases like botulism
• Endotoxins ? components of outer membrane of gram
  negative bacteria not deadly ex. Food poisoning

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Protection against bacterial diseases

• Advances in sanitation have minimized occurrences
  of bacterial diseases
• Antibiotics substance that kills or slows down
  the growth of bacteria help cure diseases caused
  by bacteria
• Education Ex. Lyme disease

Necrotizing Fascititis - destruction of fascia
(connective tissue covering of muscle) caused by
in invasive group of beta-hemolytic
streptococci can cause severe and rapid tissue
destruction
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Antibiotic Resistance

• Some bacteria contain plasmids that make them
  resistant to antibiotics. These bacteria survive
  when exposed to the antibiotic, and then
  replicate. Therefore the population becomes full
  of the antibiotic-resistant strain, and then we
  have no way to fight it. This is becoming a
  problem because of the excessive use of
  antibiotics.

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Bacteria as Biological Weapons

• October 2001 ? endospores of Bacillus anthracis
  found in postal service causes anthrax
• Middle Ages, bacterium Yersinia pestis causes the
  Bubonic Plague in Europe
• Many countries have agreed to stop producing
  biological weapons, however, how many countries
  are holding up that pact is unknown

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Helpful Bacteria

• More common than the harmful are the helpful
  bacteria
• Important in nutrient cycling and decomposition
• Help with nitrogen fixing
• Bioremediation ? use of organisms to remove
  pollutants from air, soil, and water

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Viruses
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Viral Structure

• Considered genes in a box
• All viruses are made up of two things
• Nucleic Acid (DNA OR RNA) not both
• Capsid (Protein coat)

Bacteriophage a virus that infects bacteria
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Virus Facts

• Can ONLY reproduce inside living cells (called
  host cells)
• They use the materials of the host cell to make
  their components for them
• Virus reproduction ?
• Lytic Cycle
• Lysogenic
  Cycle

Note Viruses are NOT cellsthey are not
prokaryotes or eukaryotes
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Lytic Cycle

• Called virulent viruses
• Kill host cell right away (cell bursts called
  lysis)
• See picture and understand process

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Lysogenic Cycle

• Called temperate viruses
• Does not kill host cell right away, stays
  dormant in host cell DNA until outside stress
  (sunlight, stress) causes the virus to activate
  and come out
• DNA is incorporated into bacterial cells DNA
  now called a prophage

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Disease Causing Viruses - Animals

• Viruses cause many diseases
• RNA viruses ? influenza (flu!), measles, mumps,
  AIDS, polio
• DNA viruses ? hepatitis, chicken pox, herpes
• If a virus attacks a cell that doesnt divide
  (ex. Nerve cells with polio), it can cripple you
  for life
• Hard to create antiviral drugs because it is hard
  to kill the virus without killing the host cell
• Antibiotics do NOT work on viruses!

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Retroviruses

• Type of RNA virus
• Contains an enzyme called reverse transcriptase
  which does reverse transcription ? makes DNA from
  RNA
• Retro means backward
• Example HIV, AIDS

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Disease Causing Viruses - Plants

• Viruses can also attack plants and destroy entire
  fields of crops
• Ex. Tobacco mosaic virus
• Injured plants are more susceptible to virus
  attack because it is easier to get past the cell
  wall
• Pass onto offspring
• Genetically engineering plants that are resistant
  
  to viruses

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Emergence of Viruses

• Three processes contribute to the emergence of
  viral diseases
• Mutations
• Contact between species (bird flu)
• Spread from isolated populations (AIDS)

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Immune Response

• Immune system recognizes and defends against
  invading microbes
• General response and then a more specific
  response
• Acquired Immunity ? develops after exposure to
  pathogen
• Antigen ? foreign molecule that elicits an immune
  response
• Ex. Surfaces of viruses, mold, bacteria, dust,
  pollen, etc.

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Antibodies

• Antibody ? protein found in blood that protects
  body against antigens specific!
• Immune system has good memory ? once exposed,
  will react more quickly next time around

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Vaccine

• Vaccination (immunization) ? body is introduced
  to a weakened version of a disease causing
  microbe body makes antibodies so that if it is
  exposed, it will be ready to fight it off
• Widespread vaccinations polio, mumps, measles,
  and smallpox
• Can be used for viral OR bacterial (typhoid)
  diseases
• Viruses can be PREVENTED using vaccines

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Sections Covered

• Chapter 16 ?
• 16.7 16.16
• Chapter 10 ?
• 10.17 10.23
• Chapter 24 ?
• 24.4