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Prokaryotes: Bacteria & Archaebacteria

Prokaryotes: Bacteria & Archaebacteria. SBI 3U Ms.Zafar. Photosynthesis Vs. Chemosynthesis. Ecosystems depend upon the ability of some organisms to convert inorganic compounds into food that other organisms can then exploit

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Prokaryotes: Bacteria & Archaebacteria

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  1. Prokaryotes: Bacteria & Archaebacteria SBI 3U Ms.Zafar

  2. Photosynthesis Vs. Chemosynthesis • Ecosystems depend upon the ability of some organisms to convert inorganic compounds into food that other organisms can then exploit • Together photosynthesis and chemosynthesis, fuel all life of Earth  methods of primary food production

  3. Chemosynthetic Bacteria • From inorganic  organic • Do not need sunlight for energy • Chemosynthetic bacteria run on chemical energy! • Energy coming from Earth itself • Ex:Beggiatoa

  4. Photosynthetic Bacteria • Conduct photosynthesis • Consist of bacteriochlorophyll • Ex: Cyanobacteria

  5. Bacteria are very abundant! Almost 1,000,000,000,000 in a 10 mL of soil! They are the most abundant life forms on Earth!

  6. Characteristics of Bacteria • Prokaryotic  All bacteria are single-celled • Bacterial cells contain no membrane-bound nucleus or organelles • Bacterial cells have a single chromosome • Bacteria reproduce asexually by binary fission (splitting into 2)

  7. The Structure of Bacteria • Cell wall  support • Cell membrane  controls the passage of materials • Cytoplasm  consists of ribosomes • DNA  genetic information • Some have flagella for aid in locomotion

  8. Identification & Classification • Bacteria can be classified according to appearance since most bacteria display one of three basic shapes: • Spherical (cocci) • Rod-shaped (bacilli) • Spiral (spirilla)

  9. Cocci • If cocci live as separate cells  monococci • If cocci live in pairs  diplococci • If cocci live in chains  streptococci • If cocci live in clusters  staphylcocci • Ex: Meningococcus  diploccocus

  10. Bacilli • Can exist as single cells  bacilli • Pairs  diplobacilli • Chains  streptobacilli • Ex: Bacillus anthracis

  11. Spiral Bacteria • Spirilla only exist as single cells • Ex: Borelliaburgdorferi

  12. Gram Stain: Another way of Classifying Bacteria • A way of differentiating between two groups of bacteria • Universally used! • Gram Positive  retain crystal violet stain • Gram Negative  appear pink! • The difference between gram-positive and gram-negative bacteria lies in the ability of the cell wall of the organism to retain the crystal violet • Gram positive are more common and less pathogenic • http://www.youtube.com/watch?v=aJpZzF3h3kc

  13. Nutrition • Most bacteria are heterotrophs obtain energy from other living organisms • Some are autotrophs  either photoautotrophs or chemoautotrophs (sunlight vs. chemical reactions)

  14. Reproduction: Binary Fission! • Asexual reproduction • Similar to mitosis • Single strand of bacteria DNA replication  identical genetic material being transferred to new cell • After replication, bacterium produces a cross wall and divides (the other cell may separate or remain attached)

  15. Binary Fission, Continued… • E.coli bacterium can produce between 10 and 100 million bacteria in 12 hours! • Higher rate of mutations

  16. Conjugation • Not common in bacteria – but does happen! • In conjugation: 2 conjugal bacteria (donor and recipient), make cell-t0-cell contact by means of a cytoplasmic bridge • Plasmids transferred from donor to recipient • Plasmid: small circular DNA strand

  17. Endospores • Used during extremely unfavorable conditions • Endospore inside bacterial cell • Thickened wall surrounding genetic info and cytoplasm • Origin cell disintegrates  resistant to heat and cannot be destroyed easily! • When conditions become better, wall breaks down and an active bacterium emerges

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