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Bacteria

Bacteria. Microorganisms. Microorganisms (microbe) are very small organisms which are usually only visible through a microscope. Some microbes are unicellular (one cell) while others are multicellular (more than one cell). Microorganisms. Multi - Mould. Uni - Euglena. Bacteria.

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Bacteria

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  1. Bacteria

  2. Microorganisms • Microorganisms(microbe) are very small organisms which are usually only visible through a microscope. • Some microbes are unicellular (one cell) while others are multicellular (more than one cell).

  3. Microorganisms Multi - Mould Uni - Euglena

  4. Bacteria • Bacteria are unicellular microorganisms typically a few micrometres in length. • They were first observed by Anton van Leeuwenhoek in 1676, using a single-lens microscope. He called them “Animalcules”. • Bacteria have a wide range of shapes, ranging from spheres to rods and spirals.

  5. How Big are ... ?

  6. Bacteria Types • Cocci – spherical bacteria. • Streptococcus pyogenes (causes strep throat). • Bacilli – rod shaped. • Salmonella enterica (causes typhoid fever).

  7. Bacteria Shapes • Vibrio – bent rods. • Vibriocholerae (causes cholera). • Spirilla – Spiral shaped. • Treponemapallidum (causes syphillis).

  8. Bacteria Shapes

  9. Bacteria Structure • Copy and Label the following diagram…

  10. 8 1 6 5 2 3 7 4 Cilia

  11. Bacteria Structure • Capsule – A slimy outer shell that gives protection. • Cell Wall – Provides structure and support. • Cell Membrane – Controls movement of materials in and out of the bacteria.

  12. Cell Membrane Cell Wall Capsule

  13. Bacteria Structure • Nuclear Material (DNA) – Controls all cell processes which take place in the cytoplasm. Bacteria Have No Nucleus! • Cytoplasm – The semi-fluid interior of the cell where chemical reactions occur.

  14. Bacteria Structure • Flagella – Tail-like projection used to help the bacteria move around.

  15. Reproduction • Bacteria reproduce asexually by a process known as Binary Fission. • The bacteria grow larger, the DNA replicates, then the cell splits in two. • In ideal conditions, bacteria can reproduce as often as every 20 minutes.

  16. Binary Fission • Each new bacterium is genetically identical.

  17. Binary Fission Video

  18. Binary Fission • A certain kind of bacteria can reproduce every 20 minutes. • Complete the table on the right and plot the bacteria's growth against time on a line graph.

  19. Binary Fission • The rapid increase in numbers in the steep part of the graph is called exponential growth. • Eventually the lack of food and build up of waste products will cause the number of bacteria to level off and even decrease. No. Bacteria Time (min)

  20. Reproduction • If conditions are inhospitable, some bacteria can produce spores which can survive for years. • What conditions are required for growth?

  21. How Bacteria Feed • Most bacteria are consumers, meaning they feed off other organisms as they can not make their own food. • Bacteria fall into two main feeding groups: • Parasites • Saprophytes

  22. How Bacteria Feed • Parasite – an organism which lives and feeds off other living organisms. • Saprophyte – an organism that feeds off dead material. • E.G. compost

  23. How Bacteria Feed • Bacteria feed by releasing digestive enzymes which pass through the cell membrane and break food down outside the bacteria. • The broken down food then enters the bacteria. • This process is called extracellular digestion.

  24. Extracellular Digestion

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