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BACTERIA. The Oldest Living Structures on The Earth. CLASSIFICATION. Living things can be grouped in THREE domains. Prokaryotes account for two of the domains. Eukaryota are all eukaryotic organisms. DOMAIN ARCHAEA.
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BACTERIA The Oldest Living Structures on The Earth
CLASSIFICATION • Living things can be grouped in THREE domains. • Prokaryotes account for two of the domains. • Eukaryota are all eukaryotic organisms
DOMAIN ARCHAEA • Most inhabit extreme environments on the earth. There are THREE main groupings. • Methanogens – are anaerobic and live in swamps, marshes, the gut of animals and sewage treatment ponds • Extreme Halophiles – live in high salt areas such as the Dead Sea and Great Salt Lake • Extreme Thermophiles – live in hot springs with temperatures of 60 to 80 celsius.
DOMAIN BACTERIA • Bacteria account for most prokaryotes. • Includes the spirochetes, gram-positive bacteria and cyanobacteria. • These are the bacteria that we will concentrate upon this year.
Size Relationships Micron Virus (.05 – 1 micron) Bacteria (.5 – 1.5 microns) Red blood cell(5 microns) White blood cell(5 – 8 microns) Sperm (60 microns)
Bacterial Shapes • Bacillus bacteria are rod shaped. • Cocci bacteria are round. • Spirillum are spiral shaped
Identification Gram Stain The Gram stain differentiates bacteria on the basis of structure and composition of the layers of the cell wall. Upon completing the stain, Gram positive bacteria appear purple and Gram negative bacteria appear pink. Gram positive cell walls have a simpler structure than Gram negative cell walls. Also note the shapes of bacteria represented here.
General Structure • Nearly all prokaryotes have cell walls • Bacteria have one major chromosome and rings of DNA called plasmids. • Ribosomes are present to help in protein formation. • Many disease causing bacteria have a thick outer slime capsule for protection. • Many bacteria have small hair-like pili to attach to other cells.
Bacterial Cell Structure • The CELLS ALIVE site will teach you about bacterial cell structure. At the site click on Cell Models on the right and when the page appears click on Bacteria to learn more about the structures.
Bacterial Motility A motile E. coli propels itself from place to place by rotating its flagella. To move forward,the flagella rotate counterclockwise and the organism "swims". But when flagellar rotation abruptly changes to clockwise, the bacterium "tumbles" in place and seems incapable of going anywhere. Then the bacterium begins swimming again in some new, random direction. Swimming is more frequent as the bacterium approaches a chemoattractant (food). Tumbling, hence direction change, is more frequent as the bacterium moves away from the chemoattractant. So it is a complex combination of swimming and tumbling that keeps them in areas of higher food concentrations.
Bacterial Reproduction • Prokaryotes reproduce asexually by binary fission thus making new DNA almost continually . • They can exchange genetic material in three ways: transformation where genes are taken up from the surrounding environment, conjugation where genes are transferred from cell to cell and transduction where genes are transferred between prokaryotes by viruses.
Bacterial Population Growth Click on the Cells Alive! icon and when you reach that page scroll down to DIVIDING BACTERIA. On viewing the dividing bacteria take note of the FOUR stages of the population growth curve.
Photoautotrophs use the sun’s energy and manufacture sugars. Chemoautotrophs need only carbon dioxide to obtain energy from inorganic substances. Photoheterotrophs are unique and use light to generate energy but must obtain but must obtain carbon in organic forms. Chemoheterotrophs use organic molecules such as sugar for energy. Bacterial Nutrition
Obligate aerobes must live where there is oxygen present. Obligate anaerobes must live where there is no oxygen. They get there energy through fermentation. Facultative anaerobes can live where there is oxygen or no oxygen. Aerobic vs Anaerobic
Not all bacteria are bad!! • Many bacteria aid in the decomposition dead organisms and waste. • Bacteria control the nitrogen cycle. • Bacteria is used to make cheese and yogurt. • Bacteria can be used to make antibiotics. • Bacteria are used to make sauerkraut. • Bacteria are used to clean up oil spills. • Bacteria are very useful in genetic engineering.
Food Bourne Bacteria Can Harm You Some of our more notorious food bourne bacteria are botulinum, salmonella, staphylococcus and E. coli. Clicking the icon above will lead you to a site with information on these bacteria.
Freezing Refrigeration Pasteruization Canning Salting Lactic acid (sauerkraut) Vinegar Methods of Food Preservation