| What are bacteria? | prokaryotic and unicellular microorganisms. They are the simplest and most abundant structres on earth's surface. |
| Why do bacteria expand fastly? | Their expansion is due to their highly metabolic diversity and rapid division |
| Are bacteria essential for world life? | the vast majority is essential as a source of significant economic products (vitamins, antibiotics) and play a role in decomposition and recycling of soil organic matter.
However some are pathogenic for both animals and plants. |
| Describe the morphology of monera | come in great sizes and shapes, most are from 0.2-2 microm in diameter or 2-8 microm in length. most are single celled, but others are found in colonies or as filaments of joint cells, they have three main shapes :spehrical coccus, rod shaped bacillus, spiral. |
| Describe cocci bacteria. | usually round but can be oval, elongated or flattened on one side. |
| How do cocci divide to reproduce? | cells remain attached to each other, pairs are called diplococci, chainlike cells are called streptococci. |
| Describe bacilli. | appear as single rods. |
| How do bacilli reproduce? | pairs (diplobacilli) chains (streptobacilli) |
| Describe spiral bacteria. | have one or more twists, never straight. |
| What are the types of spiral bacteria? | vibrios (curved rods) spirilla(helical shaped like a spring not flexible) spirocheetes (spring but flexible) |
| What do bacterial cytoplasm contain? | No nuclei, mitochondria, ER, golgi complex, lysosomes. cell membrane encloses dense cytoplasm called (cytosol) containing ribosomes and enzymes needed for metabolism. Some bacteria have gas vacuoles that allow them to sink deeper in aqua. DNA is single circular chromosome, double stranded assosciated with different proteins, histones) located in nucleoid. |
| What are plasmids? | small extrachromosomal DNA molecules capable of self-replication. They often bear genes conferring resistance to antibiotics (capsules) |
| Describe bacterial cell membrane? | selectively permeable, (selective passage of molecules-nutrients wastes...) in photosynthetic bacteria, membrane invagination form thylakoids (photosynthesis site) cell membrane is surrounded by cell wall ensuring protection, stiffness and resistance to osmotic pressure. cell wall is the main difference that characterizes Eu and Archeabacteria. |
| What are flagella? | They are tails that allow motility, found once or more in a bacteria, their rotation produces cell movement and cells with no flagella motile through secrete sticky substances, and may be involved in virulence (ghargharina) |
| What are fimbriae? | filamentous structure, serves to attach organism to a food source or other surfaces. |
| What are pilli? | filamentous structures involved in conjugation between prokaryotes, serving first to connect to cells and then draw them together for DNA transfer by retracting (like bees) some are involved in pathogenicity and also serve as receptors for specific bacteriophages. |
| How are bacteria able to orient? | Through chemical stimuli (chemotaxis-movement) or light stimuli (phototaxis) |
| What are the necessary elements for a bacteria to metabolize? | energy and carbon. |
| Classify bacteria according to energy source? | phototrophs (light, convert light to chemical energy via photosynthesis)
chemotrophs (inorganic or organic chemicals) |
| Classify bacteria according to carbon source | Autotrophs (using CO2 as carbon source)
Heterotrophs (organic compounds f.i. glucose) |
| What are the main types of heterotrophs? | saprophytes (majority sapros=rotten) parasitic or symbiotic |
| Talk about saprophytes. | carbon source are dead or partially dead organic matter in presence or absence of O2 decomposers of organic matter into inorganic state (C,N,S,P) |
| Talk about symbiotic heterotrophs. | (symbiotic=mutual benifit) as Rhizobium lives inside roots of legumes and fix N2 which is not directly used by a plant. |
| Talk about parasitic heterotrophs. | use organic matter in plants and animals, the become pathogenic if they are at origin of disease. |
| How can we classify bacteria based on O2 usage? | strict aerobic require O2 for respiration
strict anaerobic O2 poisons them
Facultative aerobic able to live regardless |
| How can we classify bacteria by Heat usage? | psychrophilic (low temp)
mesophilic (moderate temp)
moderate thermophilic (high temp)
hyperthermophilic (very high temp) |
| What are the necessary elements for growth of bacteria? | heat and O2 |
| What are Eubacteria? | EU=true, diverse but conform general characteristics, classified based on staining properties, type of metabolism, shape, cell wall structure, locomotion type (motility) |
| What do bacterial cell walls have in common? | they contain peptidoglycans (carbohydrates connected to polypeptides) |
| How are Eubacteria classified according to cell wall? | according to wall structure identified by gram staining:
gram positive (single thick layer of peptidoglycans)
gram negative (two layers one thin inner layer and one outer similar to plasma membrane. |
| What are endospores? | spores formed within the cell wall of a parent ""Gram+""" bacteria, their production increases survival ability for bacteria, and can remain viable (able to multiply) for centuries under uncomfortable conditions resisting desiccation (dehydration) and not killed by high temperatures (80C) suspended in boiling water for over 20 min without dying. |
| what is cyanobacteria composed from? | bluish green, sometimes purplish photosynthetic bacteria, have chlorophyll "a" (present in all photosynthetic bacteria, carotenoids, and other accessory pigments, phycobilins. |
| What gives cyanobacteria its color? | phycobilins involved in capturing of light energy and mask chlorophyll. |
| What are the types of phycobilin? | phycocyanin (blue pigment) phycoerythrin (red pigment) |
| How is cyanobacteia's plasma membrane? | they form many invaginations, often cocentric and parallel, called thylakoids, phycobilin is located on the outer thylakoid/ |
| What is the main sugar reserve for cyanobacteria? | glucose. |
| How do cyanobacteria move? | through sliding (no flagella). |
| What type of bacteria is cyanobacteria? | gram-, can be unicellular or colonies or multicellular filaments called trichomes. |
| what is the role of filamentous cyanobacteria ? | fixing atmospheric N2 through specialized cells, heterocysts, some form resistant cells called akinetes with thick wall and resistant to drought. |
| Where are cyanobacteria mainly found? | bottom of deep water and moist soils, some develop on water surfaces called planktonic species. |
| Talk about mycoplasma. | particular group of bacteria lacking cell walls, have many forms stick to branched filaments, all parasites cause lung diseases for animals and phtopathologic diseases in plants. |
| What are archaebacteria? | group of primitive bacteria present since 3.5 billion years, very different than other prokaryotes (absence of peptidoglycans in cell walls/ have unusual lipids- ether not ester- in plasma membrane/ distinctive RNA molecules/ RNA polymerase is like eukaryotic one) |
| Where does archaebacteria inhibit? | extreme environments, unsustainable to eubacteria hot springs (temp>100C deep sea vents that spew sulfide) , some live in soil others live in marine environments that exceed oceanic picoplankton (not pathogens to humans) |
| How are archaebacteria classified base on metabolic characteristics? | Metahnobacteria, Halobacteria, Extreme thermophile and thermoplasma. |
| Talk about mehanogens. | Produce methane from H2 and CO2, chemoautotrophs and strict anaerobic, use ammonium as a nitrogen source, but can fix nitrogen, common in tidal marshes and ocean depths. used as decomposers for wastewater treatments, they produced the largest gas reserves also found in the cattle and other ruminant's intestine, play a role in cellulose digestion. |
| Talk about Halophiles. | Live in areas where salt concentration is high, used for production for kitchen salt, most extreme ones live in (12-23% NaCl) cell walls, ribosomes and enzymes are stabilized by Na+ they are slightly aerobic, can be chemheterotroph, for some light intervenes in synthesis of ATP without intervention of chlorophyll pigment. ATP production is due to protein, bacteriorhodopsin present in plasma membrane, giving pink color to colonies forming masses in sea water. |
| Talk about extreme thermophiles. | live in hot and acidic medium, growth is optimal at more than 80C and pH 2-4 strict anaerobic found in places rich in sulfur, such as hotsprings in Iceland, also thrive in hydrothermal fissures on ocean floor |
| Talk about thermoplasma. | one species belonging to genus thermoplasma lack cell wall have a small size and can be spherical or filamentary, live in places with temperature 32-80 C facultative anaerobic. |
