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Identifying Prokaryotes

Learn about the different shapes and arrangements of prokaryotic cells, their movement mechanisms, how they obtain energy, the types of respiration they undergo, and their methods of reproduction.

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Identifying Prokaryotes

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  1. Identifying Prokaryotes

  2. 1. Cell Shape and Arrangement • 3 basic shapes • Rods (bacilli) • Spheres (cocci) • Spiral (spirilla)

  3. 1. Cell Shape and Arrangement • Arrangement • Colonies or pairs (diplo) • Chains (strepto) • Clusters (staphlo)

  4. 2. Cell Wall • in order to study bacterial cell walls, they must be stained • Stain contains 2 dyes: (i) crystal violet – purple - gram- positive bacteria (one thick layer of carbohydrates and proteins in cell wall) (ii) safranine – red - gram-negative bacteria (two layers in cell wall; second layer of carbohydrates and lipids)

  5. 3. Bacterial Movement • Some have one or more flagella; other lash, snake, spiral forward, or glide along secretions of slime • Some do not move at all Bacterial movement 1

  6. 4. How Bacteria Obtains NRG • Autotrophs - produce their own food; two types i) phototrophic – trap NRG of sunlight (like plants) ii) chemotrophic – live in harsh environments and obtains NRG from inorganic compounds (eg. H2S, S, Fe)

  7. 4. How Bacteria Obtain NRG b) Heterotrophs • cannot make their own food (i) chemotrophic – obtain NRG by taking in organic molecules then breaking them down and absorbing them into our cells; we are chemotrophic heterotrophs

  8. (ii) Phototrophic • Are photosynthetic (use sun’s NRG), but also require organic compounds for nutrients

  9. 5. Bacterial Respiration • Organisms (such as bacteria) need constant energy through respiration and fermentation • Bacteria can survive almost anywhere because of their ability to live in almost any environment

  10. 5. Bacterial Respiration • obligate aerobes- need constant oxygen supply • obligate anaerobes- do not require oxygen (must live in an oxygen free environment, absent from water) • facultative anaerobes- can survive with or without oxygen; do not require it but can survive in it.

  11. 5. Bacterial Respiration • Respiration= the process in which oxygen is used, and food is broken down for the release of energy. • Fermentation= process that enables cells to carry out energy production without oxygen

  12. 6. Bacterial Growth and Reproduction • In favourable conditions bacteria can grow and divide rapidly, reproducing in several ways. a) Binary Fission- Bacteria grows to double its size, replicates its DNA and divides in two, reproducing 2 identical cells. (asexual)

  13. b) conjugation • bacteria transfer parts of their genetic information from one cell to another through a protein bridge (sexual) • New cell has a new combination of genes which increases a population’s diversity.

  14. Spore Formation • in unfavourable conditions many bacteria form spores (endospores) • spores enclose DNA and cytoplasm and allow bacteria to remain dormant (“hibernating”) in conditions that would otherwise kill the bacteria. • when conditions become favourable again, spores open and bacteria emerge.

  15. Importance of Bacteria • Bacteria are very important to humans: • Food: e.g. beverages, cheese, yogurt, sour cream, pickles, wine • Industry: e.g. help clean up oil spills by digesting petroleum, mining minerals. • Genetic Engineering

  16. Symbiosis • bacteria develop a close relationship with other organisms which the bacteria and the other organism both benefit. (e.g. e coli bacteria is found in human digestive tract) • intestine provides warm safe home with lots of food for bacteria and we get help with digesting food and make some vitamins we can’t produce.

  17. 7. Bacteria in the Environment • Nutrient flow: -bacteria recycle and decompose (break down) dead material • Bacteria are saprophytes (organisms that use the complex molecules of a once living organism as their source of energy and nutrients) • i.e. when a tree dies it goes through many changes: weakens, crumbles and disappears.

  18. 2) Sewage Decomposition • Bacteria is used in the treatment of sewage • Bacteria break complex compounds from waste into simpler ones • Provides water, N2 and CO2, as well as other products that are used as fertilizers.

  19. 3) Nitrogen Fixation • all living organisms require nitrogen (don’t get a useful form from atmosphere) • when cyanobacteria and other bacteria take N2 from air and convert it to a form plants can use. • Bacteria are the only organism capable of this • Many plants have symbotic relationships with nitrogen fixing bacteria

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