Transcript Comparing Archaea and Bacteria

Comparing Archaea and Bacteria
Recall
Archaea and Bacteria more
different than an apple tree
and a blue whale!
Scientists then assigned the rank of
Domain to highlight these
differences
Tree of Life - Domains
Archaea
Three major types of archaea
1) Methanogens
2) Halophiles
3) Thermophiles
Methanogens
• Methane producing bacteria
• Live below surfaces in swamps, bogs, marshes
and sewage treatment plants
• Use CO2, N2, or HS for energy
• Expell CH4 as a waste product
Halophiles
• Salt loving archaea
• Live in salt pools, evaporation ponds etc.
• Live in salt concentrations of 15% or greater
(normal seawater is 3.5%)
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Thermoacidophiles
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Extreme heat environments
Live in hot sulphur springs
Use sulphur for energy
Some live near volcanoes
Grow best at 80oC + temperatures
Similarities and Differences
between Archaea and Bacteria
• In the following slides, we will look at:
– Morphology – Size, shape
– Nutrition – what it eats
– Habitats – where it lives
– Reproduction
– Classification
Morphology - Size
Morphology - Shape
Spherical forms are called
cocci (plural) or coccus (singular)
Enterococcus – found in
intestines of warm blooded
animals
Morphology - Shape
Rod forms are called bacilli (plural)
or bacillus (singular)
E.Coli – found in intestines
(cows), strain 0157 can lead
to food poisoning in humans
Morphology - Shape
Spirrila - Spiral shaped
Aggregations: Cells Grouped Together
Some individual prokaryotic cells
(bacteria or archaea) group
together
Streptococcus bacteria are found
in chains of spheres
Streptobacillus bacteria are rod
shaped and found in chains
Comparing Nutrition
Archaea  process of methanogenesis to obtain
nutrients. Methanogenesis is an anaerobic process
that occurs in environments that lack oxygen
Some Archaea use sunlight as a source of metabolic
energy but no reliable evidence of photosynthesis.
Bacteria  some are photosynthetic
Example: Cyanobacteria use solar energy
to convert carbon dioxide and water into
sugar and oxygen.
Comparing Habitats
Both archaea and bacteria occupy environments with
oxygen (aerobic) and without oxygen (anaerobic)
Archaea  ability to live in extreme environments called
extremophiles.
Bacteria  organisms that occupy environments with
moderate (less extreme) conditions called mesophiles.
There are few extremophilic bacteria.
Habitats of Extremophiles
Reproduction – Binary Fission
Prokaryotes reproduce through the asexual process of
binary fission  producing two genetically identical cells
Conjugation
Conjugation  there is transfer of genetic material (DNA)
Involving two cells (prokaryotes)
A pilus
transfers
DNA
material
Plasmids are
small loops of
DNA that can be
transferred.
Endospores:
Protecting Genetic Material
 dormant bacterial cells
 able to survive for long periods during
extreme conditions
E.g. freezing or high temperatures, radiation & toxic chemicals)
Endospores
Identifying Bacteria & Archaea
A Gram stain is used to divide bacteria into 2 groups
Gram-positive bacteria have a
Gram-negative bacteria have a
thick protein layer on their cell
wall and stain purple.
thin protein layer on their cell
wall and stain pink.
Bacteria & Human Health
A) Clostridium
botulinum is an
anaerobic bacterium
that can cause
illness in humans
B)Streptococcus
pygones is a
Gram-positive
bacterium that
causes strep
throat infections
C) Streptococcus
mutans is a Gram
positive
bacterium
that causes tooth
decay