Download Bacteria and Viruses

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Bacteria and Viruses
Bacteria
 Oldest living organisms
 Microscopic prokaryotes
 Bacteria=prokaryotes,prokaryotes=bac
teria
 Previously called Kingdom Monera
2 New Domains for Bacteria
 Archaea and Eubacteria
Overview Cell Structure
Structure
Function
Cell Wall
Protects and gives shape
Outer
Membrane
Protects against antibodies (Gram Neg. Only)
Cell
Membrane
Regulates movement of materials, contains enzymes
important to cellular respiration
Cytoplasm
Contains DNA, ribosomes, essential compounds
Chromosome Carries genetic information
Plasmid
Contains some genes obtained through recomb.
Capsule &
Slime Layer
Protects the cell and assist in attaching cell to other
surfaces
Endospore
Protects cell against harsh environments
Pilus
Assists the cell in attaching to other surfaces
Flagellum
Moves the cell
Archaea
 Live in extreme conditions
 Most similar to eukaryotes
Types of Archaea
Methanogens: Harvest energy by
converting H2 and CO2 into methane gas
 Anaerobic, live in intestinal tracts
Extreme halophiles: Salt loving, live in
Great Salt Lake, and Dead sea.
Thermoacidophiles: Live in acid
environments and high temps.
 Hot Springs, volcanic vents
Eubacteria
 Found everywhere else
 Most common
 Commonly called germs
Classification of Bacteria
Shape
 Bacillus-rod shaped
 Coccus- sphere shaped
 Spirillum-spirial shaped
Classification of Bacteria
Obtaining Energy & Nutrients
 Photoautotrophs-use photosynthesis
 Major component of plankton
 Produce large % of oxygen
 Ex:cynanobacteria
 Chemoautotrophs- inorganic materials
 Use sulfur, nitrogen, or simple organic
compounds
Classification of Bacteria
Obtaining Energy and Nutrients(con’t)
 Heterotrophs (most prokarytoes)
 Dead organisms,parasites, or
pathogens
Classification of Bacteria
 Gram Stain
 Produced by peptidoglycan in cell
wall
 Gram-positive retain stain and
appear purple
 Have thicker layer in cell wall.
 Gram-negative do not retain stain
and appear pink stain instead.
Gram Staining
Reproduction
Binary Fission
 Asexual reproduction
 1 cell divides into 2 cells
 Usually identical
 Genetic mutations produce new
forms of bacteria
 Plamids-extra loops of DNA
Binary Fission
 Step 1: DNA is copied and Cell
grows
Binary Fission
 Step 2:Cytoplasm and Cell Divide
Genetic Recombination
Allows bacteria to obtain new genetic
material
1. Conjugation-bacteria exchange
genetic material
2. Transformation-receive DNA
from the environment
3. Transduction-DNA transferred by
a virus
Genetic Recombination
Characteristic
Transformation Conjugation
Transduction
Method of
DNA Transfer
Across cell
wall and cell
membrane of
recepient
Through a
conjugation
bridge
between two
cells
By a virus
Plasmid
transfer
Yes
Yes
Not likely
Chromosome
transfer
No
Sometimes
No
Antibiotic
resistance
acquired
Yes
Yes
Sometimes
Conjugation
Transformation
Transduction
Survival
 Endospores
 Produced under harsh conditions
 Forms inside bacteria
 Resistant to radiation,extreme
temperature, lack of oxygen,etc
Bacterial Diseases
Bacteria cause disease by…
 Producing toxins
 Toxin-poisonous chemical
 Released or stored in bacteria
 Ex:Colstridium botulinum
 Destroying body tissues
 Enzymes break down host tissues
 Ex: Tuberculosis, and Sreptococcus
 Treatment- antibiotics
Bacterial Diseases
Antibiotic Resistance
Bacteria’s ability to tolerate anitbiotics
 Antibiotic-inhibit the growth or kill
bacteria
Plasmids usually transmit genes for
antibiotic resistance.
Caused by over use of antibiotics
Viruses
Viruses
Viruses are not alive because…..
1.Not made of cells
2.Do not grow
3. Do not maintain homeostasis
4.Do not reproduce on their own
But they do have a major impact on
the living world
Structure of Viruses
All viruses have a:
 nucleic acid
 Capsid
 Optional Structures
 Envelope
 Tail fibers
Viral Nucleic Acids
DNA Virus
 Contain DNA
only
 Ex:herpes virus
RNA Virus
 Contain RNA
only
 Retroviruses turn
RNA to
DNA,then
replicate
 Ex:HIV
Capsid & Envelope
Capsid
 Made of protein
 Encloses genetic
material
 Proteins match the
host cells
 Come in a variety
of shapes
Envelope
 Membrane
surrounding
capsid
 Made of proteins,
lipids,and
glycoproteins
 Receptors help
virus enter cell
Tail Fibers
Bacteriophages
 Viruses that infect
bacteria
 Tail and tail fibers
used like a
syringe
 Inject viral DNA
into cell
Reproduction
Lytic Life Cycle
1.virus attaches to cell and injects DNA
2.use host cells organelles to make viral
DNA and proteins.
3.New viruses are assembled in host cell.
4. Host cell breaks open and releases new
viruses.
5. New viruses infect new cells.
Reproduction
Lytic Life Cycle (con’t)
Host cells die
Virulent virus use lytic cycle
Ex: HIV, Rabies, etc
Reproduction
Lysogenic Life Cycle
1. Viral DNA become part of the host
cells DNA. (becomes a prophage)
2. Viral DNA replicates with host cells
DNA
3. Replicated host cell contain viral DNA
(becomes a provirus)
4. Host cell does not die
Reproduction
Lysogenic Life Cycle (con’t)
 Temperate viruses may enter lytic
cycle
 Provirus may become a permanent
part of the hosts DNA
 Ex:chickenpox
Lytic & Lysogenic Cycles
Viral Diseases
 Causes disease in bacteria,plants, and
animals
 Viruses are specific to their hosts
 Symptoms are caused by…
 Toxic parts (envelope)
 Cause cell to produce toxins
 Lysis of host cell
 Results in fever and body aches
Viral Diseases
 Possible causes of cancer
 HPV (cervical cancer)
 Hepatitis B (liver cancer)
 No treatment for viral diseases only the
symptoms
Prevention
 Vaccines- weakened form of the
pathogen
Emergent Diseases
 Newly recognized diseases or
diseases that have reemerged
 New Diseases
 Swine Flu, Avain Flu, SARS,etc
 Re-emergent
 Measles, Hanata Virus, Drug Resistant
TB
Disease Transmission
 Direct Contact-kissing,sex,etc
 Fomites (indirect contact)-door
knobs,keyboards,etc
 Droplet- sneezing, coughing
 Airborne- droplets or dust
 Vector- animals like mosquitoes,
rats, dogs,etc
Important Scientists
 3 scientists made major breakthrough in the
fight against disease and infections.
 Alexander Fleming
 Louis Pasteur
 Robert Koch
Important Scientists
 Alexander Fleming is credited for his discovery
of penicillin, a very important antibiotic.
 Louis Pasteur is credited for developing
sterilization techniques to help kill pathogens.
 Robert Koch is credited for developing steps to
diagnose diseases.
Identifying Pathogens
Koch’s Postulates
1. Find and Isolate pathogen from
diseased animal or person.
2. Grow pathogen in a lab.
3. Infect a healthy animal.
4. Isolate the pathogen from second
animal.