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Viruses
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DNA or RNA or both?
Surrounded by protein
Not cellular
Not “alive”
What characteristics of “living”
organisms do viruses lack?
NO
cell organization
response to stimuli
homeostasis
growth
development
Maybe?
regulation
reproduction
Yes
Heredity
Viral Classification
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Replication dependent on living
organisms
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Often highly specific to a host
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Highly specific cells within a host
Shapes
Replication in Bacteriophage
Lytic Cycle
Lysogenic Cycle
1.
2.
Attachment
Penetration
3.
4.
5.
Synthesis
Assembly
Release
• Historically lethal
• High mutation rate
(less problematic)
• Infects many types
of animals
(highly problematic)
Virus Strains
• Classified according to
type of proteins
• Recombination between
different strains causes
problems
• Hong Kong Flu
− H3N8 – ducks
− H2N2 – humans
Ebola
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5 different viruses
Discovered in mid 1970’s
Single stranded RNA
Causes hemorrhagic fever
2014 outbreak - 8000 deaths
High mortality rate
Transmission – broken
skin/mucous membranes
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Each day 6000 people die in
Africa from Aids
11,000 newly infected
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“All of a sudden, the beaver flips
over and comes back to life”
http://www.washingtonpost.com/local/cr
ime/woman-83-attacked-by-rabidbeaver-at-lake-barcroft-in-fairfaxcounty/2012/09/05/e778ec02-f79411e1-8253-3f495ae70650_story.html
Prokaryotes
Bacteria
There are more individual
prokaryotes in your large
intestine than there are cells
in your body
Life in the clouds
Santl-Temki et al. 2013. PLOS one
Prokaryotes
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Small
Unicellular
No nucleus
Asexual reproduction
Modes of gene transfer
Lack organelles
Little morphologial diversity
Simple flagella
Metabolic diversity
Ecological diversity
Oldest life-form
Gram-negative bacteria
Outer membrane
Pili
(structures
used for
attachment)
Peptidoglycan
layer
Cell wall
Nuclear
area
(nucleoid)
Storage granule
Plasmid
(DNA)
Flagellum
Ribosomes
Bacterial chromosome
(DNA)
Capsule
Plasma
membrane
Prokaryote
Diversity
https://www.
youtube.co
m/watch?v=
v1NnMmw8
v80
Gene Transfer Between Prokaryotes
Figure 6.2
6-1
Table of metabolic
Diversity in Prokaryotes
Prokaryotic Diversity
• Recognition that there are two
fundamentally different kinds of prokaryotes
– Bacteria
– Archaea
• 1977: Carl Woese – RNA analysis
These "bacteria" appear to be no more
related to typical bacteria than they are to
eukaryotic cytoplasms.
1987 – 12 phyla
2003 – 29 phyla
2012 – 52 phyla?
Bacteria vs. Archaea
• Cell walls contain
peptidoglycans
• Plasma membrane
composed of lipid bilayer
• Antibiotics inhibit
growth
• No true peptidoglycan in
cell walls
• Bi-layer with different
lipids and bonds –
monolayer
• Growth not inhibited by
antibiotics
Several other differences associated with
DNA replication and gene expression
• Simple RNA
polymerase enzyme
• Unique translation
initiation
• Multiple RNA
polymerases (Like Eukaryotes)
• Translation is similar to
Eukaryotes
Archaea Diversity
Many technological applications using prokaryotes
Using bacteria to
produce
pharmaceuticals