Virus – infectious
strainorofparticle
DNA orthat
RNAcan
covered
Pathogen
– an organism
cause
by a protein
ancapsid.
infectious disease.
http://www.youtube.com/watch?v=ql-The variety of
shapes are due to the different
proteins that YkaQj8CQ&safe=active
make up the capsid
AIDS
Avian Flu
Influenza
SARS
Adenovirus
HPV
-The surface proteins on the virus determines
which host cell the virus infects.
Avian Flu Virus
Coronavirus
Retrovirus – uses RNA to make DNA
HIV
http://www.hhmi.org/biointeractive/media/hi
v_life_cycle-lg.mov
Viral Infection
PG 550 Fig 18.6
Lytic Infection
-Virus replicates many times….lots of offspring
-Destroys the host cell after viral replication and release
of offspring.
Lysogenic Infection
-Virus combines with the host cell’s DNA….all daughter
cells will have the viral genes.
-Causes no initial harm to the cell, though it can alter some
of the cell’s traits. At any time the prophage can enter the
http://highered.mcgrawhill.com/sites/0072995246/student_view0/chapter8/lambda_phag
lytic cycle.
e_replication_cycle.html
-Virus that lies dormant http://www.courses.fas.harvard.edu/~biotext/animations
/lyticcycle.html
http://www.courses.fas.harvard.edu/~biotext/ani
mations/lysogeny.html
Bacteriophages – viruses that infect bacteria
Viroid – infectious particles that cause disease
in plants
-single stranded RNA…no protein capsid
-passed through seeds and pollen
Apple Scar
Skin Viroid
Tomato Spotted
Wilt Tospovirus
Choke disease
Blast disease
Prion – an infectious protein particle that cause
other proteins to fold incorrectly
-have no genetic material
Mad Cow Disease
BSE – Bovine Spongiform
Encephalopathy
http://learn.genetics.utah.edu/content/begin
/dna/prions/
Bacteria – one celled prokaryotic microorganisms
– obligate anaerobes
are poisoned by
oxygen
– obligate
aerobes need
oxygen
– facultative
aerobes can
live with or
without oxygen
• Bacteria commonly come in three forms.
– rod-shaped, called bacilli
– spiral, called spirilla or spirochetes
– spherical, called cocci
Rod-shaped
Spherical
• Archaea have many shapes.
Spiral
• Gram staining identifies bacteria.
– stains polymer peptidoglycan
– gram-positive stains purple, more
peptidoglycan
– gram-negative stains pink, less peptidoglycan
Gram-negative bacteria have a thin layer of
peptidoglycan and stain red.
Gram-positive bacteria have a thicker
peptidoglycan layer and stain purple.
Strategies for Survival
Binary Fission – divide in half
Conjugation – exchange of genetic material
Endospore – protective wall that protect the bacteria from
harsh environments.
Beneficial Roles
Mutualistic – bacteria benefit from living in human
digestive system b/c they get food and
a place to live. Humans benefit from
bacteria because they help them absorb
essential nutrients.
Antibiotics
http://www.hhmi.org/biointeractive/media/penicillin-lg.mov