DOMAIN EUBACTERIA AND DOMAIN ARCHAEA Objectives 1 State
DOMAIN EUBACTERIA AND DOMAIN ARCHAEA Objectives: 1. State some key characteristics (structure, feeding, reproduction, metabolism) of domain Eubacteria and Archaea. 2. Describe the shapes and arrangements of each domain. 3. Explain potential biotechnology related to the two domains. H/W: p. 46 -53 #1 -5, 7 -10
PHYLOGENY OF THE DOMAINS (there are more than 12) Which domains share the most recent common ancestor?
DOMAIN BACTERIA (EUBACTERIA) appeared on Earth more than 3. 5 mya prokaryotic live as single cells or in colonies cell wall contains peptidoglycan DNA is a single, circular chromosome in addition, some have plasmids which are small, circular extra-chromosomal DNA § these contain a small number of “non-essential” genes (antibiotic resistance)
BACTERIAL CELL
DOMAIN BACTERIA (EUBACTERIA) MOST are BENEFICIAL (e. g. food production, nitrogen fixation) Only a few are pathogenic (cause disease)
CELL WALL STRUCTURE the cell walls of bacteria contain a molecule called peptidoglycan a Gram Stain can differentiate between the two groups of bacteria: thick or thin peptidoglycan it’s another way to classify bacteria peptidoglycan (purple layer)
CLASSIFYING BACTERIA (a)cocci (sing. coccus) (b)bacilli (sing. bacillus) (c)spirrilla (sing. spirillum) common arrangements often, the genus and/or species name is based on shape and arrangement Streptococcus pyogenes chains round “an agent that causes pus”
METABOLISM Autotrophic – assemble complex carbon molecules (e. x. sugars) from simple inorganic molecules like CO 2 , H 2 O, and minerals § Phototrophs - energy from the sun cyanobacteria § Chemotrophs – energy from chemicals, such as NH 4 (ammonia) and H 2 S (hydrogen sulfide) bacteria found in swamps, deep ocean vents Heterotrophic – get nutrients and energy by eating other living organisms or their remains Photoheterotroph – can do both Heliobacter pylori (stomach ulcers)
METABOLISM Obligate aerobes – require O 2 to get energy from food (all animals and plants) Facultative aerobes – perform aerobic respiration and anaerobic respiration (fermentation) – with or without O 2 Obligate anaerobes – unable to survive if O 2 present (poison)
REPRODUCTION Binary fission – asexual (not mitosis!) Conjugation – “sexual” - pilus enables the transfer of a copied plasmid
BACTERIAL DISEASES Exotoxins –produce and release toxins § Clostridium botulinum (botulism) Endotoxins – contain toxins that are released if the bacteria die § Escherichia coli (E. coli) strain O 157: H 7 – Walkerton, Ontario 2000 § town of 5000, 5 people died
BACTERIAL DISEASES Cholera - Vibrio cholerae Lyme disease – Borrella burgdorferi Pertussis -Bordetella pertussis Scarlet Fever – Streptococcus pyogenes Tetanus - Clostridum tetani
SAY CHEESE!
DOMAIN ARCHAEA originally thought to be unusual eubacteria unlike all other organisms § cell wall and membrane have a unique chemical composition § most lack peptidoglycan § unique genetics(different from other two domains) “extremists” § cell walls and membranes are very resistant to physical and chemical pressures § some have survived being boiled in strong detergent!
CLASSIFYING ARCHAEA METHANOGENS – produce methane - live in low oxygen environments such as sediments of swamps, sewage lagoons, digestive tracts = farts HALOPHILES – “salt loving” - highly saline environments such as the Dead Sea and salt preserved food THERMOPHILES – extremely hot environments (hot springs, hydrothermal vents), optimal growth temp. 70 -95 °C PSYCHROPHILES – cold-loving - found in Antarctic /Arctic Oceans and deep ocean, optimal growth temp. -10 to -20 °C
ARCHAEA AND BIOTECHNOLOGY archaean enzymes being used in biotechnology PCR (polymerase chain reaction) § technique used to create multiple copies of an isolated DNA sample (identification) § archaean DNA polymerase functions at high temperatures § DNA polymerase from bacteria or us would be destroyed at high temps
ARCHAEA TO THE RESCUE! antibiotics – new class of potentially useful antibiotics recently discovered bioremediation – some metabolize metal ions in polluted areas
THE ORIGIN OF LIFE earth’s early atmosphere contained water, methane and ammonia, but lacked oxygen the environment was high in UV and temperature present-day archaea thrive in these types of conditions 1 st organisms?
S. MILLER AND H. UREY (1952) after one week: § as much as 10 -15% of the carbon was now in the form of organic compounds § 2% percent of the carbon formed made amino acids – the building blocks of proteins
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