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Viruses
Virus
“intracellular parasites”
• small infectious agent that can replicate
only inside the living cells of organisms
Chicken Pox and Shingles Virus
Virion: an entire virus particle
• Consists of:
• DNA or RNA
• Protein Coat – called a
capsid
• Sometimes a lipid
envelope around the
protein coat
• You Tube Lytic Cycle
(2:17)
Bacteriophage Virus
• capsid
Sometimes glycoprotein spikes
to help the virus enter and exit the
host cell
LYTIC INFECTION
• Animation of a Lytic Infection
• McGraw Hill Life Cycle of a T2 Phage
HIV
• The Human Immunodeficiency Virus (HIV)
• Can lead to AIDS (acquired immunodeficiency
syndrome)
HIV INFECTION
• HIV infection: a retrovirus (high level)
• Shows receptors and how anti-viral
drugs can be effective
HIV budding
from a
lymphocyte
Lytic Infection
Examples Lytic Infections
• Common Cold
• Influenza
• Rabies
• TMV
(tobacco mosaic virus)
Lysogenic Infection
Temperate Viruses
• Also called lysogenic
viruses
• are those that reproduce
without killing their host
cell.
Common Lysogenic Virus
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Herpes (genital and cold sore)
Papilloma HPV (cervical cancer)
Retrovirus
Hepatitis B
Chicken Pox
Retroviruses
• Retroviruses use RNA instead of
DNA as their nucleic acid core.
• also contain the enzyme reverse
transcriptase
Retrovirus Examples
• HIV
• Rous sarcoma (first one
discovered)
• Leukemia viruses
Viroids
• Viroids are naked • Infect plants
circular RNA (no
protein coat)
molecules that are
several hundred
nucleotides long.
Viroid Attack on Potatoes
• Used to make
varieties in flowers
Prions
• a form of a normal
protein that is not
folded correctly.
• Cause degenerative
brain disease
Mad Cow Disease
• BSE = bovine spongiform
encephalitis
• It's ...BSE You Tube
• Can cause CJD in humans
CJD
• Creutzfeldt-Jakob disease (CJD) is a
form of brain damage that leads to
a rapid decrease of mental function
and movement.
• You Tube The BSE Prion and Variant
CJD
Vaccines
• “Harmless” variants or
derivatives of pathogenic
microbes that stimulate the
immune system to make
antibodies against the
pathogen.
Edward Jenner First Vaccine
(for smallpox)
• Gave cowpox to his son first
• Lots of people were getting smallpox
BACTERIA
• Prokaryotes
• Most of its DNA is in a single
chromosome
Bacteria Can Transfer DNA in 3 Ways
• 1. Transformation – uptake of foreign DNA
from the surrounding environment
• 2. Transduction – transfer of bacterial genes
by a bacteriophage
• 3. Conjugation – physical union of two
bacterial cells as they “mate”
Transformation
Transduction
Conjugation
Bacterial Plasmids
• F Factor = fertility plasmid
F Plasmid
• Resistance Plasmid
• Carry genes to destroy antibiotics
Identifying Bacteria
• McGraw Hill Prokaryotic Cell Shapes
Can you name these shapes?
Can you name these shapes?
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A Bacilli with and without flagella
B Streptococci
C Staphylococci
D Diplococci
E Spirochete
F Club rod
G Filamentous
H Streptobacilli
Spores
• dormant, tough, and non-reproductive
structure produced by certain bacteria