Bacteria and Viruses

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Bacteria and Viruses

• Biology
• Chapter 10

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Kingdom Monera

• Divided now into
• Kingdom Archaebacteria
• Kingdom Eubacteria
• Outnumber all other living organisms combined
• Microscopic - 1000 times smaller than most human
  cells
• Exist EVERYWHERE!
• 100-20,000 in every cubic meter of air

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Classification and Morphology

• Microbiology the study of microscopic organisms
• Bacteria all prokaryotic lack nucleus
• Pathogenic disease causing (minimal)
• Decomposer breaking down of substances

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Kingdom Archaebacteria

• Live in extreme conditions.
• Thermoacidophiles highly acidic soils and hot
  springs (230 degree F)
• Methanogens live anaerobic conditions producing
  methane gas as waste
• Halophiles salt-loving live in extremely salty
  conditions metabolize salt to produce ATP

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Kingdom Eubacteria

• Largest of the two bacteria kingdoms
• Scientists are continuing to fight over the
  organisms contained in this kingdom.
• Most live in non-extreme environments.

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Bacterial Shapes, Sizes, and Colonies

• Shape and Size
• Coccus spherical (1um diameter) a period
  could easily have 5,000 coccus lined up across
  its diameter
• Bacillus rod (1 um in width and 2-10 um in
  length)
• Spirillum spiral or corkscrew shape (slightly
  longer than bacillus)

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• Colonies unicellular but living together
• Diplo two cells joined together
• Strep joined end-to-end in long chains
• Streptococcus
• Streptococcus pneumoniae
• Staph clustered together like grapes
• Staphylococcus

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Bacteria Cell Walls and Capsules

• Bacteria
• Plasma membrane phospholipid bilayer which
  controls the flow of substances into and out of
  the cell
• Cell wall directly outside the plasma membrane
  no cellulose maintain shape of cell
• Capsule outside cell wall made of sticky
  carbohydrates protects the cell from dry spells

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Bacterial Cytoplasmic Structures

• Nuclear area - DNA material appears as a circular
  chromosome
• Plasmid one or more smaller circular DNA
  chromosomes carry only a few nonessential genes
• Mesosomes twisted invaginations of the plasma
  membrane supplying additional surface area for
  metabolic processes to occur

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Bacteria Locomotive Structures

• Flagella long threadlike whip
• Bacteria without flagella appear to vibrate back
  and forth as water molecules bump into them can
  also appear to migrate with the flow of the
  liquid
• A.k.a Brownian movement

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Bacterial Reproduction and Growth

• Bacteria grow to full size and divide every 30
  minutes over 1 billion bacteria is 15 hours
  under 24 hours the cells would weigh over 2000
  tons
• Growth rate this fast cannot be sustained for long

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Asexual Reproduction

• Simple Binary Fission
• DNA replicates
• Plasma membrane has an invagination and forms two
  daughter cells
• Can be completed in 9 minutes

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Bacteria and Nutrition

• Autotrophs
• Photosynthetic similar but uses different light
  wavelengths
• Chemosynthetic involves converting inorganic
  compounds to other usable forms and capturing the
  energy
• Heterotrophic vast majority digesting organic
  substances
• Parasitic feeding on a living host
• Saprophytic feeding on dead organic matter

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Conditions for Optimal Growth

• Moisture all require moisture to grow capsule
  maintains internal moisture
• Temperature ideally normal is around 80-100
  degree F
• pH most bacteria prefer a neutral condition
• Nutrition heterotrophs must obtain energy as
  well as materials necessary for bacterial
  biosynthesis

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Optimal Growth

• Bacteria are very environmentally specific what
  is beneficial to one may kill another
• If conditions turn unfavorable then the bacteria
  create an endospore.
• Endospore one or more layers of hard material
  that form around the nuclear area to protect the
  DNA from the environment when favorable
  conditions return the endospore will weaken and
  the bacteria will break out

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Bacteria and Oxygen

• Obligate anaerobes organisms that grow only in
  the absence of oxygen
• Obligate aerobes organisms that grow only in
  the presence of oxygen
• Facultative anaerobes organisms that can grow
  with or without oxygen

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Bacteria and the Transfer of Genetic Material

• Conjugation the bacteria line up side by side
  and a tube is formed that connects the two
  genetic material is passed in one direction
• Transformation living bacterial cells take up
  other bacterias free DNA from nonencapsulated
  bacteria
• Transduction transfer of genetic material by
  way of a virus called a bacteriophage

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Terminology

• Microbiologist
• Bacteria
• Decomposer organism
• Thermoacidophile
• Methanogen
• Halophile
• Coccus
• Bacillus
• Spirillum
• Capsule
• Nuclear area
• Plasmid
• Mesosome

• Chemosynthetic
• Parasitic
• Saprophytic
• Endospore
• Obligate anaerobe
• Obligate aerobe
• Facultative anaerobe
• Conjugation
• Transformation
• Transduction
• Heterotroph
• Autotroph
• Brownian movement

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Viruses

• Virology the study of viruses
• Viruses contain two basic parts
• Core either DNA or RNA (never both)
• Capsid a protein covering
• Envelope only some have it made of lipids
• Virion entire virus unit
• Obligate intracellular parasites must have host
  for life

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Classifying Viruses

• Two large groups
• DNA containing or RNA containing then whether
  the DNA or RNA is single or double stranded
• Also classified by
• Shape
• Presence or absence of an envelope
• Method of infecting and replicating within the
  host cell

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Viroids and Prions

• Viroid smaller than a virus a short single
  strand of circular RNA no capsid or envelope
• Prion smaller than a viroid abnormal form of a
  protein does not contain any nucleic acids

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Vaccinations

• Typically a small dose of the actual virus in a
  weakened condition.
• Allows the body to build up an immunity for the
  disease.

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Viral Replication

• Virulence the ability of a pathogen to affect
  cells
• Lytic cycle the activity cycle of a virulent
  virus

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Lytic Cycle

• Lytic cycle has five stages
• Attachment virus attaches to host cell
• Entry virus core is injected into the host cell
• Replication and transcription using the cells
  enzymes and organelles, the virus begins to
  produce multiple copies of the viral nucleic acid
• Assembly the virus proteins form capsids around
  the replicated viral DNA or RNA forming new
  virions
• Release lysis occurs and the virions are
  released into the organism to attach to new host
  cells and repeat the lytic cycle.

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Lytic vs. Lysogenic Cycles

• The lytic cycle begins to destroy the host cell
  upon entry.
• The lysogenic cycle allows the virus to remain
  dormant within the host cell and is duplicated
  when the cell undergoes mitosis thereby creating
  a whole population of cells that contain the
  virus. Once the virus is stimulated it enters
  the lytic cycle and destroys the host cell after
  stimulus it returns to dormancy.

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Viral Diseases

• VERY specific regarding the host cell.
• Diseases are controlled through vaccinations.

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Disease Terminology

• Pathogen an agent that invades the body and
  causes a disease
• Incubation period the time between being
  infected and the first appearance of a symptom
• Communicable disease a disease that can be
  spread from one person to another by either
  direct or indirect means
• Vector insects or other arthropods that carry
  pathogens from one host organisms to another
• Carrier a healthy-appearing individual can
  spread the disease to others but have no symptoms
  themselves

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• Structural defenses prevent pathogens from
  entering the body
• Nonspecific defenses internal responses to the
  presence of a pathogen
• Specific defenses chemotherapy directed toward
  a specific pathogen

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• Disorders afflictions not caused by a pathogen
• Inherited
• Injuries
• Organic
• Tumor a group of non-functioning cells that
  grow a different structure
• Benign tumor is slow growing and localized
• Malignant tumor grows rapidly and chaotic
• Metastasize separate from parent tumor and
  travel