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• Prokaryote: no nucleus
– Chromosome & plasmids float freely in cytoplasm
• Ribosomes: create proteins
• Flagella: used in movement
pili
• Pili: act as anchors
plasma
membrance
• Capsule: outer coating
chromosome
• Endospore: “cocoon” to
protect DNA in harsh timescell wall
plasmid
This diagram shows the typical structure of a
prokaryote. Archaea and bacteria look very
similar, although they have important
molecular differences.
flagellum
Prokaryotes are widespread on Earth.
• Prokaryotes can be grouped by their need for
oxygen.
– obligate anaerobes
are poisoned by oxygen
– obligate aerobes need
oxygen
– facultative aerobes can live
with or without oxygen
The bacteria that causes TB lives
in your lungs…which type is it?
Bacteria and archaea are structurally similar but
have different molecular characteristics.
• Bacteria commonly come in three forms.
– rod-shaped, called bacilli
– spiral, called spirilla or spirochetes
– spherical, called cocci
Lactobacilli: rod-shaped
Enterococci: spherical
Spirochaeta:spiral
• Archaea have many shapes.
Spirochaeta:
spiral
Enterococci:
spherical
Bacteria (aka Eubacteria)
• Common to most
environments on Earth
• Identified by Gram Stain test
– Gram negative: stains pink
(harder to treat because of
thick capsule)
– Gram positive: stains
purple (easier to treat)
• Treatments differ depending GRAM NEGATIVE
upon results
GRAM POSITIVE
Gram Stains
Gram-negative bacteria have a thin layer of
peptidoglycan and stain red.
Gram-positive bacteria have a thicker peptidoglycan
layer and stain purple.
• Which is harder to treat?
• Name one way to treat bacterial infections.
Bacteria have various strategies for survival.
• Reproduce asexuallythrough binary
fission (less
diversity).
• Prokaryotes
exchange genes
during conjugation
(more diversity).
• Bacteria may
survive by forming
endospores.
conjugation
bridge
TEM; magnification
6000x
Not all bacteria are harmful, most are helpful…
• Bacteria helped create the
ozone.
– Ex: cyanobacteria-autotrophic
bacteria
– Create oxygen for life on earth
• Bacteria return nutrients to
the soil in nature
– Ex: saprophytes
• Bacteria used in medicine
• Bacteria used in food
– To make cheese, bread, wine,
yogurt, soy sauce
HEALTHY
MODERATE PERIODONTITIS
GINGIVITIS
ADVANCED PERIODONTITIS
• Live in extreme environments
• 1) Methanogens:
– Anaerobic
– Produce methane gas as a waste product
– Habitat: Swamps, sewage, digestive tract
2) Thermophiles
• Heat and acid loving
prokaryotes
• Habitat: Deep sea vents,
volcanoes, hot springs
(230°F)
3) Halophiles
– Thrive in areas of high salt concentration
• Salt normally dehydrates organisms
– Use salt to make energy
Name this bacteria shape!
Name this bacteria shape!
Name these cell parts!
Name the process shown in this animation.