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Microbiology

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Microbiology Bacteria and Viruses Skip to last to see which sections in the book are covered in this unit! – PowerPoint PPT presentation

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Title: Microbiology


1
Microbiology
  • Bacteria and Viruses

Skip to last slide to see which sections in the
book are covered in this unit!
2
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

3
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

4
  • 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.

5
Division of Prokaryotes
  • There are two main groups of prokaryotes
  • Bacteria vs. Archaea

6
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)

7
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8
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

9
Prokaryote Shape
  • Three general shapes ?
  • Cocci (spherical)
  • Bacilli (rod shaped)
  • Spirilla or spirochetes (curved or spiral)
  • Staphlo clusters
  • Strepto chains

Spirochete ?
Cocci ?
Bacilli
10
Prokaryotic Movement
  • Use flagella
  • Different from eukaryotic flagella
  • Not made up of
    microtubules naked
    protein structure
  • Doesnt wave, it does
    propeller-like rotations

11
Oxygen Needs
  • Obligate aerobes ? must be in oxygen
  • Obligate anaerobes ? cannot be in oxygen
  • Facultative anaerobes ? can survive with or
    without oxygen

12
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

13
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14
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

15
Transduction
Transformation
Conjugation
16
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

17
Prokaryotic Nourishment
  • modes of nutrition ? how organisms get two
    major resources carbon and energy
  • Autotrophs producers
  • Heterotrophs consumers

18
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

19
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

20
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21
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

22
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
23
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.

24
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

25
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

26
Viruses
27
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
28
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
29
Lytic Cycle
  • Called virulent viruses
  • Kill host cell right away (cell bursts called
    lysis)
  • See picture and understand process

30
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

31
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32
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!

33
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

34
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

35
Emergence of Viruses
  • Three processes contribute to the emergence of
    viral diseases
  • Mutations
  • Contact between species (bird flu)
  • Spread from isolated populations (AIDS)

36
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.

37
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

38
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

39
Sections Covered
  • Chapter 16 ?
  • 16.7 16.16
  • Chapter 10 ?
  • 10.17 10.23
  • Chapter 24 ?
  • 24.4
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