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Prokaryotes

Prokaryotes. Laboratory 2 Biology 171. Three domains of life: two are prokaryotic. Three domains of life: two are prokaryotic. Prokaryotes. An organism that lacks a membrane-enclosed nucleus and other membrane-enclosed organelles . Prokaryotes.

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Prokaryotes

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  1. Prokaryotes Laboratory 2 Biology 171

  2. Three domains of life: two are prokaryotic

  3. Three domains of life: two are prokaryotic

  4. Prokaryotes An organism that lacks a membrane-enclosed nucleus and other membrane-enclosed organelles

  5. Prokaryotes An organism that lacks a membrane-enclosed nucleus and other membrane-enclosed organelles

  6. Prokaryotes These organisms have circular DNA, with very simple transcription processes

  7. Domain Archaea – thermophiles (extremophiles)

  8. Today in Lab • Exercise 1: General Features of Bacteria • Activity A: Bacterial Shapes • Activity B: Colonies • Exercise 2: Investigating Microorganisms • Activity A: Gram Stain • Activity B: Antibiotic Sensitivity Test • Observing Cyanobacteria

  9. Bacteria • Unicellular microorganisms • a few micrometers in length • Numbers… • 40 million bacterial cells in a gram of soil • 1 million in a milliliter of freshwater • Approximately 10x as many bacterial cells as human cells in the human body – most on skin & digestive tract • Approximately 5 nontrillion (5 x 1030) on earth! 5,000,000,000,000,000,000,000,000,000,000

  10. Where are bacteria found? • EVERYWHERE! • In the soil and water • On and in our bodies • In the air we breathe • Critical to nutrient cycling as decomposers • Some cause disease • Vast majority are harmless, but half of all human diseases are caused by bacteria

  11. Anatomy of a Bacterium • Some examples of differences between bacteria and eukaryotic cells? • Cell wall • Capsule • Ribosomes • How could these differences help fight disease?

  12. Activity A: Bacterial Shapes Spirilla

  13. Activity B: Bacterial Colonies • the population of bacteria derived from one or a few cells, visible with the unaided eye • Exponential growth • For example, if we start with only one bacteria which can double every hour, by the end of one day we will have over 16 million bacteria. • At the end of 24 hours, there are 16,777,216 bacteria.  

  14. Colony Shape

  15. Colony Color Why Care? Interpreting Plates

  16. Diversity of Bacterial Colonies

  17. Exercise 2: Activity A: Gram Stain • Invented by Hans Christian Gram in 1884 to discriminate between two types of bacteria that had similar symptoms. • Gram-positive bacteria tend to be more sensitive to most antibiotics. • Other antibiotics work better on gram-negative bacteria. • Broad-spectrum antibiotics work on both types.

  18. Activity B: Antibiotic Sensitivity Test Antibiotics – drugs that either kill or inhibit the growth of bacteria. They assist the immune system…blocks cell division (peptidoglycan synthesis)

  19. Antibiotics in Healthcare • Antibiotics such as penicillin and tetracycline have helped save millions of people around the world. • Penicillin was discovered in 1941, before this there was no cure for diseases such as pneumonia, strep throat, and gonorrhea. • Patients with infected wounds often had to have limbs amputated or risk infection spreading to the rest of the body.

  20. Cyanobacteria (not in manual) • Def: photosynthetic, oxygen-producing bacteria, formerly called blue-green algae • Anabaena • Oscillatoria • Nostoc • Observe these bacteria by making a wet mount slide and observing with a compound microscope. • Draw pictures, record their behaviors, colors, etc. Genus

  21. Anabaena Filamentous – grows in long strings of many cells Heterocysts – involved in nitrogen fixation - which is the process where gaseous nitrogen is “fixed” into ammonia, necessary for building many parts required for life, e.g.DNA and proteins

  22. Oscillatoria Filamentous – grows in long strings of many cells

  23. Nostoc Colonial filamentous – grows in long strings of many cells that cannot function (i.e. survive) individually Heterocyst – anoxic environment…nitrogen fixation cannot happen in the presence of oxygen

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