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PROKARYOTES

PROKARYOTES. THEY ARE EVERYWHERE. The Major Similarities Between the Two Types of Cells (Prokaryote and eukaryote) Are:. They both have DNA as their genetic material. They are both membrane bound. They both have ribosomes . They have similar basic metabolism .

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PROKARYOTES

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  1. PROKARYOTES

  2. THEY ARE EVERYWHERE

  3. The Major Similarities Between the Two Types of Cells (Prokaryote and eukaryote) Are: • They both have DNA as their genetic material. • They are both membrane bound. • They both have ribosomes . • They have similar basic metabolism . • They are both amazingly diverse in forms.

  4. How Prokaryotes Differ from Eukaryotes • Smaller and lack membrane bound organelles • Have cell walls but composition is different from that of plants and fungi • Have simplier genomes • Differ in genetic replication • Protein synthesis • recombination

  5. Prokayotes Have a Tremendous Impact on the Earth • Small percentage cause diseases • Decomposers • Key to life-sustaining chemical cycles • Form symbiotic relationships • Mitochondria and Chlorophast may have evolved from such symbiosis

  6. Three Domains

  7. Two Kingdoms of Prokaryotes • Archaebacteria • Evolved from the earliest cells • Inhabit extreme environments • Eubacteria • Modern prokaryotes • More numerous

  8. Structure • Cocci (spheres) • Bacilli (rods) • Spirilla and spirochetes (helices)

  9. Prokaryotic Cell Wall • Major material is PEPTIDOGLYCAN • Modified sugar polymers cross-linked by short polypeptides • Exact composition varies among species • Some antibiotics work by preventing the formation of cross links thus preventing the formation of a functional cell wall

  10. Gram-Positive Have simple walls with large amounts of peptidoglycan Stain blue Gram-Negative More complex with less amounts of peptidoglycan Outer lipopolysaccharide-containing membrane Stain pink Often pathogenic Gram Stain – a Stain Used to Distinguish Two Groups of Bacteria

  11. Flagella Filaments Gliding Taxis – movement to or away from a stimulus. Stimuli may be: Phototaxis Chemotaxis magnetotaxis 50% of Bacteria Use One of Three Mechanism to Move

  12. Cellular and Genomic Organization • Infolding of the plasma membrane – cellular respiration in aerobic bacteria • Cyanobacteria have thylakoid membranes • Genome as 1/1000 as much DNA as that of a eukaryote • One double stranded, circular DNA • DNA concentrated in the nucleoid region • Contain plasmids • Ribosomes are smaller and have different proteins and RNA content from eukaryotes • This allows some antibiotics to block bacterial protein production will not adversely affecting the eukaryote proteins

  13. Prokaryotes Grow and Adapt Rapidly • Binary fission • Transformation • Conjugation • Transduction • Endospores

  14. Prokaryotes May Be Grouped According to How They Obtain Energy • Photoautotrophs – photosynthetic and use light for energy • Chemoautotrophs – need only CO2 as a source of carbon and obtain energy by oxidizing inorganic substances • Photohetrotrophs – use light to make ATP but must obtain carbon in organic form • Chemoheterotrophs- must consume organic material for both energy and carbon

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