Transcript Ch20bactandvir2015

Chapter 20
Bacteria & Viruses
Germ Theory
• Discovery that microorganisms are
PATHOGENS (disease causing agents)
The germ theory of disease states that
some diseases are caused by
microorganisms. These small organisms,
too small to see without magnification,
invade humans, animals, and other living
hosts. Their growth and reproduction
within their hosts can cause a disease.
I. Bacteria
Prokaryotes
• Are ________________________-lack a nucleus and
have few organelles
• Much smaller than eukaryotes
• Eubacteria-larger kingdom than
archaebacteria;usually have protective cell wall and
determines shape
• __________________________-not such a
strong,if any,cell wall,DNA sequences more like
eukaryotes;live in HARSH environments like hot
springs or volcanic vents
Archaebacteria
Identifying bacteria:
Bacillus or bacilli
–
by shape
• 1) rod-shaped are __________________
• 2) spiral-shaped
are_______________________
• 3) spherical-shaped are cocci(coccussingular)
Spirillus or
spirilla
• by cell walls-use Gram Staining-Gram(+) have
thick_______________________walls/gram(-) have
thinner walls
• by movement-some do not move and some have
flagella
peptidoglycan
B. Metabolic Diversity
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Chemoheterotrophs
Heterotrophs
–
_____________________-must take in organic molecules
for energy and supply of Carbon-as do we
–
_____________photoheterotrophs
Autotrophs
–
____________________–
______________-as those found in volcanic vents
photoautotrophs
chemoautotrophs
Releasing Energy
– 1) Obligate aerobes-need constant supply of O2
– 2) _______________________-do not need O2
– 3) Faculatative anerobes-can survive w/or w/o
O2-example-E.coli
Obligate
anaerobes
C. Growth and Reproduction
•
_________________________grows,replicates
DNA
and splits in half
Binary fission
• ________________________-exchange genetic
info w/ a “bridge”
conjugation
• Some
produce_________________________,
which can lie dormant and germinate
spores
D. Importance of Bacteria
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Decomposers
N-fixers-for plants
Human uses-food production ;cleaning
up oil spills
Assist digestion
II. Viruses-particles of nucleic
acids,protein and sometimes lipids
capsid
• Not living-reproduce only by infecting living cells
• Usually has a DNA or RNA core w/outer protein coat
• Outer protein coat called a ______________-which
enable it to enter a host cell—often destroying host
cell
• ________________________-viruses that infect
bacteria
bacteriophage
• ____________________infection-virus enters
cell,makes copies ,and causes cell to burst
• _____________________________-virus integrates
DNA into DNA of host cell,and viral genetic info
replicates along w/host
Lysogenic
Lytic
• _______________________________contain RNA as genetic info and produce
DNA copy of RNA
retroviruses
III. Diseases
vaccination
• Bacterial
– Infect by damaging cells or releasing toxins
– Mycobacterium tuberculosis
– Streptococcus
– Cornyebacterium diptherae
– Anthrax
– Lyme’s disease
– Tetanus
– Meningitis
– Tooth decay
• prevention
– -_______________________preparation of weakened
or killed pathogens
– ________________________-compounds that block
the reproduction or growth of bacteria
antibiotic
• 2)controlsterilization,heat,disinfectantants,proper
food processing and storage
B. Viral
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Common cold
Influenza
Smallpox
Warts
AIDS
Chickenpox
Measles
Hepatitis A,B, or C
West Nile
Polio
viroids
– ________________________________singlestranded RNA moleculesw/no capsid-attack
plants
– ______________________-virus –like particles of
protein-may cause protein clumps that induce
new prions---example-Mad Cow Disease
prions