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Biology II

Biology II. Bacteria. The invention of the microscope opened our eyes to the hidden, living world around us. Microscopic life covers nearly every square centimeter of earth. Prokaryotes. The smallest and most common microorganisms

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Biology II

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  1. Biology II Bacteria

  2. The invention of the microscope opened our eyes to the hidden, living world around us. • Microscopic life covers nearly every square centimeter of earth

  3. Prokaryotes • The smallest and most common microorganisms • Unicellular organisms that lack a nucleus and a membrane bound organelles • Mainly Bacteria

  4. Prokaryotes can be divided into two very different groups • Eubacteria • Archaebacteria

  5. Eubacteria • Include a wide range of organisms with different lifestyles • Eubacteria live almost everywhere • Largest Prokaryote Domain • Cell membrane around cytoplasm • Some have an extra cell wall on the outside to resist damage

  6. Archaebacteria • Lack the same carbohydrates of eubacteria and also have different membrane lipids • Also, the DNA sequences of key archaebacterial genes are more like those of eukaryotes than those of eubacteria • Many archaebacteria live in extremely harsh environments

  7. Identifying Prokaryotes • Prokaryotes are identified by characteristics such as: • shape • the chemical nature of their cell walls • the way they move • the way they obtain energy

  8. Shapes • Bacilli – Rod shaped • Cocci – Spherical Shaped • Spirilla – spiral and corkscrew shaped

  9. Cell Walls • Eubacteria – Have peptidoglycan • Archaebacteria – Don’t have peptidoglycan

  10. Movement • Flagella • Lash, snake or spiral forward • They do not move at all

  11. Metabolic Diversity • No characteristic of prokaryotes illustrates their diversity better than the way they obtain energy

  12. Heterotrophs • Must take inorganic molecules for both energy and a supply of carbon • Chemoheterotrophs: must take in organic molecules for energy • Photo heterotrophs: Use sunlight for energy but need organic compounds for a carbon source

  13. Autotrophs • Chemoautotrophs: perform chemosynthesis to make carbon from carbon dioxide. Does not require sunlight • Photoautotrophs: Use light to convert carbon dioxide and water into carbon compounds and oxygen gas

  14. Getting Energy • Bacteria need a constant supply of energy • Obligate aerobes- Require costant supply of oxygen • Obligate anaerobes- Need no oxygen, for some oxygen will kill it • Facultative anaerobes- Survive with or without oxygen

  15. Releasing Energy • Like all organisms, bacteria need a constant supply of energy • This energy is released by the process of cellular respiration or fermentation or both

  16. Growth and Reproduction • Bacteria can grow really fast • Types of Reproduction • Binary fission • Conjugation • Spore formation

  17. Binary Fission • When a bacterium has grown so that it has nearly doubled in size, it replicated its DNA and divided in half producing 2 identical daughter cells

  18. Conjugation • Many bacteria are also able to exchange genetic information by a process called conjugation • This transfer of genetic information increases genetic diversity

  19. Spore Formation • When growth conditions become unfavorable, many bacteria form structures called spores

  20. Endospore • A type of spore formed when a bacterium produces a thick internal wall that encloses a thick internal wall that encloses its DNA and a portion of its cytoplasm

  21. Importance of Bacteria • Decomposers • Break down dead matter • Nitrogen Fixers • Converts nitrogen into a form plants use

  22. Decomposers • As decomposers, bacteria help the ecosystem recycle nutrients, therefore maintaining equilibrium in the environment.

  23. Human Uses of Bacteria • Used in food and beverage production • Industries: petroleum, water, mining, drugs • Inside of us (symbiosis) • E. Coli • Drug Research

  24. Helpful Bacteria • Bacteria help the body digest food and produce certain vitamins • Some bacteria fight off diseases • Helps break down all the dead plant and animal remains making nutrients for the soil

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