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Transcript
“The Kingdom Formerly Known as Monera” Single celled Prokaryotic bacteria and blue-green algae (cyanobacteria) Life Before Oxygen One Kingdom or two? Currently, some scientists prefer to divide the Monerans into two separate Kingdoms – Domain Archae Kingdom Archaebacteria – Domain Bacteria Kingdom Eubacteria Ancient vs. True Bacteria Differences: Ancient Bacteria (archaebacteria) – their cell walls and the lipids in plasma membranes have a different structure – Sequences of bases in the tRNAs and rRNAs of ancient bacteria are quite different – React differently to antibiotics – Able to extract nutrients from inorganic sources (called chemoautotrophs) Salt-loving Bacteria (halophiles) Live in salt-lakes The only prokaryotic organisms that inhabit the Great Salt Lake and the Dead Sea Evaporation pond on the margin of Lake Tyrrell, Australia. The salt works salt piles can be seen in the distance. Bacteria Of Boiling Hot Springs In Yellowstone National Park Heat-loving and Acid-loving Bacteria (thermoacidophiles) Occupy very hot and acidic areas Some live deep in the ocean near underwater volcanoes and thermal vents Others live in hot sulfur springs, where temperatures can reach 800C and a pH as low as 2. Castle Geyser at Yellowstone National Park Acidophilic (acid-loving) Bacteria Acidophilic microbes thrive in this biofilm growing inside an abandoned mine at Iron Mountain, Calif. Acidic mud pots at Yellowstone National Park Finally… Some scientist feel the ancient bacteria should be classified in a separate kingdom. Perhaps the ancient bacteria, the true bacteria and the eukaryotes share a common ancestor that was a very early life form on Earth. Importance of Micro-organisms Most are harmless Some cause disease ex) diptheria, plague Decompose dead animals and plants = make raw materials of life available again Convert and recycle essential elements like carbon, oxygen, sulfur, and nitrogen Some intestinal bacteria aid digestion Recalls on California produce has experts questioning farming practices 19:27:02 EDT Oct 10, 2006 Canadian Press: TOBI COHEN TORONTO (CP) - The threat of E. coli and botulism poisoning from leafy green vegetables and carrot juice produced in California has Canadians once again watching what they eat - and food experts raising questions about where it comes from. Two people in Toronto remained paralyzed Tuesday after drinking carrot juice contaminated with botulism, while three people have died and nearly 200 left ill after eating lettuce and spinach from the Golden State that was laced with E. coli. …. Recognize these? Microbiology “The study of microorganisms” Has practical applications in industry and medicine – Development of antibiotics – Manufacture of dairy products (buttermilk, cheese, yogurt, etc.) – Experimental tools in studying biological processes like metabolism, photosynthesis, enzyme action, and gene action Characteristics Structure – Unicellular – Lack a membrane-bound nucleus and organelles (aka prokaryotic) – Possess a single chromosome – Possess a cell wall (protection; osmotic balance) – Cell wall often surrounded by a capsule Diversity of size and shape: Mycoplasma genitalium 0.4 µm Haemophilus influenza 1.0 µm Staphylococcus aureus 0.9 µm Escherichia coli 1.5µm But…. Bacillus megaterium 4 µm That’s not all! RBC 8 µm General Bacterial Shapes A. This twisted shape isn't a rotini, it is the bacteria Treponema pallidum, which causes syphilis. Because of its shape, this bacteria is classified as a spirochete. B. The bacteria Neisseria gonorrhoeae, which causes gonorrhea, is considered a coccus due to its spherical shape. Reproduction Asexual – production of one or more genetically identical offspring from a single parent. Binary fission “splitting in two” Resembles mitosis, but simpler: 1. Single DNA strand copies itself 2. Cross wall produced that divides the bacterium into two identical cells • In some species, the new cells remain attached to form pairs, chains, or clusters. *genetic variations can occur within individual cells through recombinant events such as mutations Transduction The transfer of viral, bacterial, or both bacterial and viral DNA from one cell to another via bacteriophage. Conjugation Two conjugal (mating) pairs (1 donor, 1 recipient) make cell-to-cell contact Cytoplasmic bridge formed Plasmids (sections of genetic material) are transferred Two monerans separate * Not true sexual reproduction How do Monerans survive unfavourable conditions? Bacteria can become dormant (rest phase) Form endospores inside the cell A thickened wall forms around genetic material and cytoplasm Remainder of cell eventually disintegrates Resistant to heat and not easily destroyed When conditions are suitable again, the wall breaks down and activates the bacterium Nutrition in True Bacteria The success of bacteria is in part due to a wide variety of ways to obtain energy While most are heterotrophs, many are autotrophs Have developed different methods of respiration to break down stored food and release energy – Obligate aerobic – Obligate Anaerobic – Facultative anaerobe (alternate between as needed) Heterotrophs Found everywhere Not able to consume and digest food; must absorb nourishment from their surroundings (materials that are already partially digested) – Saprophytic- feed off dead organisms or organic waste (decomposers) – Parasites – live on or in living organisms; cause harm to the host in some way Photosynthetic Autotrophs “self-feeders” – combine inorganic molecules from the environment with energy from the sun to make carbohydrates (glucose –C6H1206) O2 is given off as waste (blue-green algae were important in producing this early in life’s history = creates atmosphere) In the case of Monerans, they can also absorb energy directly from the sun due the fact that they are small and all sides of the cell are exposed to the environment Photosynthetic Autotrophs Often found in puddles, ponds, streams, lakes, and moist places. Important producers in aquatic communities – basis for all of Earth’s food chains/webs (Important role as decomposers – recycle nutrients through the biosphere= heterotrophs) Chemosynthetic Autotrophs Some true bacteria are autotrophic but not photosynthetic (do not use the sun’s energy to produce food) Break down inorganic materials like sulfur and nitrogen Can be important in converting S and N compounds so that plants can use it Nutrition in Ancient Bacteria Also known as archaebacteria Live under conditions that may be very similar to those found when life was first evolving on Earth. All of the known ancient bacteria live without oxygen and are autotrophs Some live where no other organisms can exist today. Methane-producing Bacteria Chemosynthetic (convert CO2 and H2 to methane) Inhabit swamps, marshes, and other env’ts wherever there is a great deal of decaying plant matter. Also inhabits the digestive tracts of mammals, especially grazers Can be found in sewage treatment plants. Bonus Possible practical use: fuel Convert decomposing material into a usable fuel http://www.preciseenergy.com/biosyst em.htm Resource Review What would life on Earth be like if there were no decomposers to break down dead plant material, the bodies of dead animals, and the waste products generated by all living things? – Eventually, all the nutrients needed for life would be bound up in this dead matter and waste. – The raw materials needed to support new life would no longer be available.