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Microbiology. Viruses and Bacteria. History of Microbiology. Edward Jenner (1798): 1 st Vaccine Joseph Lister (1867): Aseptic Surgery Luis Pasteur (1857-1864) Fermentation Pasteurization Biogenesis Robert Koch Germ Theory of Disease (1876) Microorganism can cause disease

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microbiology

Microbiology

Viruses and Bacteria

history of microbiology
History of Microbiology

Edward Jenner (1798): 1st Vaccine

Joseph Lister (1867): Aseptic Surgery

Luis Pasteur (1857-1864)

  • Fermentation
  • Pasteurization
  • Biogenesis

Robert Koch

  • Germ Theory of Disease (1876)
    • Microorganism can cause disease
    • Koch’s Postulates
  • Pure Cultures (1881)
  • Tuberculosis (1882)

Alexander Flemming (1928): Penicillin

Jonas Salk (1955): Polio Vaccine

viruses
Viruses
  • Virus: A parasitic non-living entity!
      • Must exist within a “host”
      • No Cellular Structure
      • No cytoplasm, organelles, or phospholipid membranes
    • Capsid: Outer coat made of protein
    • Core: Central region made of nucleic acid
      • DNA or RNA
    • Envelope: Made of lipids, carbo, and proteins
    • Spikes: Used for attachment
      • Carbohydrate and protein (glycoprotein)
virus shapes
Rod-shaped:(helical)

Tobacco mosiac virus (TMV)

Spherical:(round or oval)

HIV or Aids virus

Polyhedral: (many sides)

Polio virus

Bacteriophage

Infects bacterial cells

Virus Shapes
bacteriophage
A virus that infects a bacterial cell

Used to study viral behavior

T-4 bacteriophage is commonly studied!

Bacteriophage
the lytic cycle
The Lytic Cycle

1. Attachment

Adsorption

2. Entry

3. Biosynthesis

  • Replication
  • Transcription
  • Assembly
  • Formation

4. Lysis and release

  • The cell explodes
lysogenic cycle
Lysogenic Cycle

1. Attachment

2. Entry

3. Integration

4. Cell division

Replication

5. Lysis?

  • Provirus:A virus that becomes integrated into the host cells DNA
viruses can contain dna or rna
DNA Virus

Lytic cycle

Attachment/Adsorption

Entry

Biosynthesis

Lysis and release

Lysogenic Cycle

Attachment

Entry

Integration

Cell division and possible lysis

RNA Virus

Lytic Cycle

Similar to DNA viruses

Viral RNA can serve as mRNA to construct proteins!

Lysogenic Cycle

Retrovirus: A virus that can transcribe DNA from RNA (provirus)

Reverse transcriptase: An enzyme that can reverse normal transcription (reverse transcription)!!

HIV is an example

Viruses can contain DNA or RNA
slide15
DNAmakes RNAmakes Protein

A retrovirus can reverse this sequence

The virus enters as RNA and then can manufacture DNA. It will integrate into the host cells DNA

HIV replicates 1010 times per day

It takes 6 weeks for HIV to become resistance to AZT (one of the most common drugs to treat HIV)

HIV treatment options

Triple drug therapy is a must!

1. Integrase inhibitors

2. Reverse transcriptase inhibitors

3. Protease inhibitors

HIV
bacteria living kingdom archaebacteria kingdom eubacteria
Bacteria: Living!!Kingdom ArchaebacteriaKingdom Eubacteria

Structure

  • Prokaryotic: Nucleoid region with a loop of chromosomal DNA
  • Cell wall (peptidoglycan)
  • Capsule: (outer protective coat found on some bacteria)
  • Flagella: One…or many
  • Endospore: Protective wall that surrounds some bacteria. Allows bacteria to remain dormant for long periods
slide17
Flagella: Swimming movement
    • Protein
  • Pili: Sex pilus Mediates DNA transfer during conjugation
    • Protein
    • Common pili or fimbriae: Attachment to surfaces; protection against phagotrophic engulfment
      • Protein 
  • Capsules:(includes "slime layers" and glycocalyx)
    • Attachment to surfaces; protection against phagocytic engulfment, occasionally killing or digestion; reserve of nutrients or protection against desiccation
      • Usually polysaccharide; occasionally polypeptide
  • Cell wall:
    • Gram-positive bacteria Prevents osmotic lysis of cell protoplast and confers rigidity and shape on cells Peptidoglycan (murein) complexed with teichoic acids
    • Gram-negative bacteriaPeptidoglycan prevents osmotic lysis and confers rigidity and shape; outer membrane is permeability barrier; associated LPS and proteins have various functions Peptidoglycan (murein) surrounded by phospholipid protein-lipopolysaccharide "outer membrane“
  • Plasma membrane:Permeability barrier; transport of solutes; energy generation; location of numerous enzyme systems Phospholipid and protein
  • Ribosomes: Sites of translation (protein synthesis)RNA and protein
  • Inclusions: Often storage reserves of nutrients; additional specialized functions
    • Highly variable; carbohydrate, lipid, protein or inorganic
  • Chromosome:Genetic material of cell DNA
  • Plasmid:Extrachromosomal genetic material DNA
bacterial reproduction
Bacterial Reproduction

Binary Fission: A form of asexual reproduction where the cell splits into two. (DNA must replicate first)

Plasmid Sharing: The process where bacterial cells exchange plasmid DNA using pili. (Linked to antibiotic resistance)

Conjugation: Exchange of “nucleoid” or chromosomal DNA

bacterial cell shape
Bacterial Cell Shape
  • Bacillus:Rod-shaped
  • Spirilla:Spirals
  • Cocci:Round or spherical
  • Strept:Chains
  • Staph:Clusters
  • Diplo:Two together
nutrition
Heterotrophic:Obtain energy from organic matter.

Parasitic: (+, -)

Saprophytic: Live off of dead or decaying matter

(chemo-heterotroph)

Autotrophic: Can make their own nutrients

Photoautotroph:

Use sunlight for energy

CO2 for carbon

Early blue green bacteria/cyanobacteria

Produced oxygen for early earth’s atmosphere

Chemoautotroph:

Use inorganic compounds for energy

Use CO2 for carbon

Found in hydrothermal vents

Thrive on hydrogen sulfide

Nutrition
ancient bacteria archaebacteria
Methanogens:Produce methane

Swamps, marshes, digestive tracts of mammals. Breakdown decaying matter

Halophiles: “salt loving”

Great salt lake, dead sea

Acidophiles:Thrive in acidic environments

Thermophile:Thrive at high temps

Acidophiles and thermophiles are found in yellowstone springs, hydrothermal vents. Ph is often as low as 2.

Lack peptidoglycan cell walls

Membrane lipids are different from Eubacteria

DNA sequences of many archaebacteria genes are more similar to eukaryotes than to Eubacteria

Ancient Bacteria(Archaebacteria)
the gram stain procedure
A differential stain used to separate bacteria into two groups

Based on cell wall differences

Bacteria are separated into:

Gram +

Gram -

Steps

1. Smear

air dry, heat fix

2. One minute Crystal Violet

RBD

3. One minute Gram’s Iodine

RBD

4. Decolorize with ETOH(drops)

RBD

5. 30 sec. Safranin

RBD, AD

The Gram Stain Procedure
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