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
Archaea Three major types of archaea • Methanogens • Halophiles • 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 - 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 Streptococcus bacteria are found in chains of spheres Some individual prokaryotic cells (bacteria or archaea) group together 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.
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) Plasmids are small loops of DNA that can be transferred. A pilus transfers DNA material
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 usedto divide bacteria into 2 groups Gram-positive bacteriahave a thick protein layer on their cell wall and stainpurple. Gram-negative bacteria have a thin protein layer on their cell wall and stainpink.
Bacteria & Human Health B)Streptococcus pygonesis a Gram-positive bacterium that causes strep throat infections A) Clostridium botulinumis an anaerobic bacterium that can cause illness in humans C) Streptococcus mutansis a Gram positive bacterium that causes tooth decay