Comparing Archaea and Bacteria

RecallArchaea 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 archaea1) Methanogens2) Halophiles3) 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%)

I

Thermoacidophiles

• 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 - ShapeSpherical forms are calledcocci (plural) or coccus (singular)

Enterococcus – found in intestines of warm blooded animals

Morphology - ShapeRod forms are called bacilli (plural)or bacillus (singular)

E.Coli – found in intestines (cows), strain 0157 can lead to food poisoning in humans

Morphology - ShapeSpirrila - Spiral shaped

Aggregations: Cells Grouped Together

Streptococcus bacteria are foundin chains of spheres

Some individual prokaryotic cells(bacteria or archaea) grouptogether

Streptobacillus bacteria are rodshaped and found in chains

Comparing Nutrition Archaea process of methanogenesis to obtainnutrients. Methanogenesis is an anaerobic processthat occurs in environments that lack oxygen

Some Archaea use sunlight as a source of metabolicenergy 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 FissionProkaryotes reproduce through the asexual process ofbinary fission producing two genetically identical cells

Conjugation

Conjugation there is transfer of genetic material (DNA)Involving two cells (prokaryotes)

Plasmids aresmall loops ofDNA that can betransferred.

A pilustransfersDNAmaterial

Endospores: Protecting Genetic Material

Endospores dormant bacterial cells able to survive for long periods during

extreme conditions E.g. freezing or high temperatures, radiation & toxic chemicals)

Identifying Bacteria & Archaea

A Gram stain is used to divide bacteria into 2 groups

Gram-positive bacteria have athick protein layer on their cellwall and stain purple.

Gram-negative bacteria have athin protein layer on their cellwall and stain pink.

Bacteria & Human Health

B)Streptococcuspygones is aGram-positivebacterium thatcauses strepthroat infections

A) Clostridiumbotulinum is ananaerobic bacteriumthat can causeillness in humans

C) Streptococcusmutans is a Grampositivebacteriumthat causes toothdecay