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Chapter 2

Chapter 2. 2.2 – Unicellular Organisms. Unicellular Organisms. We are multicellular organisms However, many living things are composed of just one cell These unicellular organisms are also known as micro-organisms or microbes They must also carry out life’s functions

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Chapter 2

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  1. Chapter 2 2.2 – Unicellular Organisms

  2. Unicellular Organisms • We are multicellularorganisms • However, many living things are composed of just one cell • These unicellular organisms are also known as micro-organisms or microbes • They must also carry out life’s functions • A single cell is responsible for feeding, digesting, excreting, and reproducing

  3. The Importance of Micro-Organisms • Many micro-organisms cause disease but most are harmless • Dairy products such as buttermilk, cottage cheese, and yogurt are produced by the action of micro-organisms

  4. Bacteria • Bacteria are among the most primitive and also the most plentiful organisms on Earth • Some can make their own food • Others are parasites • Parasites can live only by invading the body of an animal or a plant • Others can live with little or no oxygen

  5. Bacteria • Bacteria are prokaryotic cells • They have no nucleus, no mitochondria, and no ribosomes

  6. Bacteria Pili – hair-like structures to help bacterium attach or for movement Chromosomes – not contained in a nucleus Flagellum – whip-like tail for movement Cell Membrane Cell Wall – rigid support Capsule – Sticky coating of infective bacteria, difficult to destroy

  7. Protists • Protists are found in watereverywhere • They are neither plants or animals • Protists are eukaryotic cells • They have a nucleus and contain mitochondria, ribosomes, and lysosomes

  8. Plantlike Protists • Plantlike protists are not true plants but they do contain chlorophyll and produce their own food by photosynthesis • We are going to look at 2 types of plantlike protists: • Diatoms • Euglena

  9. Plantlike Protists Diatoms • Diatoms are found in both fresh and salt water • They contain chlorophyll and can make their own food • They are encased in two thin shells which are joined together • Each diatom has a unique shape

  10. Plantlike Protists Euglena • Euglena are similar to both plant and animal cells • If there is a lot of sunlight the euglena acts like a plant and makes it’s own food • If there is not a lot of sunlight then the euglena acts like an animal and it will feed on smaller cells

  11. Plantlike Protists Flagellum Mitochondria Golgi Apparatus Chloroplasts Contractile Vacuole – expels excess water Pellicle – flexible cell covering

  12. Animal-like Protists • Animal –like protistscannot make their own food • They must feed on things that are living or were once alive • They have all the organelles of an animal cell

  13. Animal-like Protists Amoebae • The amoeba is a blob-like organism that changes shape as it moves • It moves by stretching out a branch of cytoplasm called a pseudopod(false foot) • The pseudopodanchors to an object, and the rest of the amoeba is dragged toward it

  14. Animal-like Protists

  15. Animal-like Protists Paramecium • The paramecium uses cilia to help it move • The cilia beat in unison to create water currents that move the paramecium • Cilia around it’s oral groove create a current that draws food into the groove

  16. Animal-like Protists

  17. Fungi • Some fungi are multicellularand some are unicellular • Bread mold and mushrooms are well known fungi • Harmful fungi include those that cause ringworm and athlete’s foot

  18. Fungi • Yeast is one of the few unicellular fungi • Yeast relies on other organisms as their source of energy

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