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Introduction to Bacteria

Introduction to Bacteria. Why are there two kingdoms of bacteria?. First “observed” by van Leeuwenhoek in the 1600s. All bacteria used to be classified together until recently. The genetic materia l (DNA) of a rchaebacteria is much different than eubacteria so the kingdom was divided.

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Introduction to Bacteria

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  1. Introduction to Bacteria

  2. Why are there two kingdoms of bacteria? • First “observed” by van Leeuwenhoek in the 1600s. • All bacteria used to be classified together until recently. • The genetic material (DNA) of archaebacteria is much different than eubacteria so the kingdom was divided.

  3. Archaebacteria • Most live in extreme environments. • Probably the oldest form of life on Earth. • At least 3.5 billion years old!

  4. Eubacteria • Eubacteria are found just about everywhere that archaebacteriaare not. • Most bacteria areharmless to you and you need them to survive.

  5. The Bacterial Cell • Unicellular • Prokaryotic • No nucleus • No organelles • Smaller than eukaryotic cells • Simple structure Remember your cell diagrams from Unit 1 

  6. Inside the Bacterial Cell • Most bacteria are surrounded by a cell wall • Inside the cell wall is a cell membrane that controls what enters and leaves • “Filled” with cytoplasm • Contains ribosomes to make protein • Contains circular DNA to direct functions • Some have flagellum (plural flagella) which help the cell move

  7. Bacterial Cell Diagram

  8. Bacterial Shapes • All bacteria have one of three shapes: • Cocci – spherical • Baccilli - rodlike • Spirilla - spiral shapes • The shape of the bacteria helps to identify the type of bacteria.

  9. Bacterial Shapes Bacilli Spirilla Cocci

  10. Examples of Bacteria Shapes and Names Streptococcus pyrogenes Lactobacillus acidophillus Rhodospirillumfulvum

  11. What do bacteria eat? • Some are autotrophic • Photosynthesis – make food by using the sun’s energy • Chemosynthesis – use energy from chemical substances to make food • Others are heterotrophic • Eat nutrients from the environment or other bacteria

  12. Do bacteria breathe? • Aerobicbacteria - need oxygen to survive • They use it to break down their food • Anaerobic bacteria – do not need oxygen; it is actually deadly to them!

  13. Endospores • Endospore – a small, rounded, thick-walled, resting cell that forms inside a bacterial cell • Form when conditions become unfavorable for the growth of bacteria • Resists freezing, heating, and drying • Can survive for many years and open up when conditions are favorable again

  14. Endospores

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