Viruses
-Segments of RNA or DNA
contained In a protein coat
Viruses are not living!!!
1) Viruses are not made of cells
2) Viruses do not grow
3) Viruses can’t reproduce on their own
2 Main Shapes of Viruses
1) Helical Virus
- Rodlike
- Capsid proteins winding
around core in a spiral
2 Main Shapes of Viruses
2) Polyhedral Virus
-Many sides, roughly spherical
-Most efficient at holding viral genes
Bacteriophages
Viruses that infect
bacteria
Structure is polyhedron
capsid w/ helical tail
How can a Virus Reproduce?
Infect a living cell
Living cell reads viral nucleic acids and
produces more viruses
Bacteriophages go through the lytic or
lysogenic cycle
Lytic Cycle
Viral genes are injected into the host cell
Host cell replicates viral genes and make viral
proteins (capsids)
Genes and viruses are put together
Process repeats until cell bursts
Lytic Cycle
http://student.ccbcmd.edu/courses/bio141/lecgui
de/unit3/viruses/lytlc.html#rellyt
Lysogenic Cycle
Viral gene is inserted into host chromosome
(provirus)
When cell divides, provirus divides
Change in environment can begin lytic cycle
Lysogenic Cycle
http://student.ccbcmd.edu/courses/bio141/lecgui
de/unit3/viruses/repmatly.html
http://www.youtube.com/watch?v=_J9-xKitsd0
Emerging Viruses
Viruses that evolve in
geographically
isolated areas and
are pathogenic to
humans
Hanta Virus
Ebola Virus
Hantavirus Pulmonary Syndrome
May 1993
Acute respiratory
symptoms
Breathing in air
contaminated w/ the
virus
Urine and feces
Ebola Virus
1976
Severe, often fatal
disease
Found in humans and
non-human primates
Gabon, Sudan, the Ivory
Coast, Uganda, and the
Republic of the Congo.
http://www.cdc.gov/ncido
d/dvrd/spb/mnpages/disp
ages/ebola/ebolatable.ht
m
Why do we encounter emerging
viruses?
http://ffh.films.com/id/9505/The_Emerging_Virus
es.html
Prions
Proteins and no nucleic acids
Cause disease by influencing how proteins
fold
Misfolding spreads like a chain reaction
Mad Cow Disease
Creutzfeldt-Jakob disease
Bacteria
http://video.google.com/videosearch?hl=e
n&q=bacteria&safe=vss&um=1&ie=UTF8&sa=N&tab=wv#
What are Bacteria?
Single celled, prokaryotic organisms
1/10 the size of most eukaryotic cells
-http://www.cellsalive.com/howbig.htm
Have a single circular piece of DNA
Reproduce by Binary Fission
Anaerobic and aerobic processes (Euk are
mostly aerobic)
Flagella is simple
Some have pili
Pili
http://microbiologybytes.com/video/photosynthesis.html
Along with gel-like capsule, pili help bacteria
adhere to surfaces
Enable Conjugation-two organisms exchange
genetic material
Cell Walls
Most Bacteria have 2 types of cell walls
-Gram-negative
-Gram-positive
The 2 types differ in susceptability to antibiotics
-Chemicals that interfere with life
processes in bacteria
Three Basic Shapes
Bacillus (buh SIHL uhs)
-Rod shaped
Coccus (KAHK us)
-Round shaped
Spirillium (spy RIHL uhm)
-Spiral shaped
Baccilus
Northwestern Link
Coccus
http://biology.northwestcollege.edu/biology/b1010lab/bacillus1.jpg
Spirillium
http://biology.northwestcollege.edu/biology/b1010lab/bacillus1.jpg
Which is Which???
Aggregating Bacteria
Strepto- form filaments
Staphylo- form clusters
How Bacteria Cause Harm
Metabolize their host
Secrete chemical compounds
Metabolizing their host
Acne
Propionibacterium acnes, grow in the oil glands of skin
Metabolize certain kind of oil produced by glands
Oil glands increase oil production during puberty
Food increases so bacteria population increases
http://www.nlm.nih.gov/medlineplus/tutorials/acne/htm/_no_50_no_0.
htm
Myths
Metabolize their Host
Mycobacterium tuberculosis
Once one of most common causes of death (1.6 million in 2005)
Incidence rates have stabalized
Contracted from inhaling droplets of moisture containing bacterium
Cough up sputum (saliva mixed w/ mucus or puss) and blood, chest
pain, fever, fatigue, weight loss
Over one third of world population is infected (5-10% will become
sick)
Secrete Chemical Toxins
Staphylococcus aureus
Causes most common food poisoning
Nausea, vomiting, diarrhea
Secrete Chemical Toxins
Clostridium botulinum
Causes botulism
From improperly heated canned food
Double vision and paralysis
May die because can’t breath
1g would is potent enough to kill 1 million people
Relevance of Bacteria
Living with you
Food
Antibiotics
Living with You
Streptococcus pneumoniae - present in
upper respiratory tract of half the
population
E. coli - Present in small intestine. Aids in
digestion
Streptococcus aureus - causes most
common staph infections.
Found in Nose and on skin
Food
Fermented food
Pickles, buttermilk, cheese, saurkraut,
olives, vinegar, and sourdough bread
Antibiotics
Can be naturally produced by fungus or
imitated chemically
Penicillium was first used antibiotic
Either stop bacteria from multiplying
(bacteriostatic) or interferes with formation
of cell wall or cell contents (bactericidal)
Over 100 types and most often perscribed
medicine