1 / 35

Protista

Protista. e.g. Amoeba. Learning Objectives. Explain the nuclear structure of Amoeba Explain the sub cellular structure of Amoeba. Amoeba. Recall Protista characteristics. Contains single-celled and simple multi-cellular organisms

jade-brown
Download Presentation

Protista

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Protista e.g. Amoeba

  2. Learning Objectives • Explain the nuclear structure of Amoeba • Explain the sub cellular structure of Amoeba

  3. Amoeba

  4. Recall Protista characteristics • Contains single-celled and simple multi-cellular organisms • They are eukaryotic – they have a membrane-enclosed nucleus and membrane enclosed organelles • Some feed by taking in organic substances, others can photosynthesise.

  5. Examples include: • Amoeba – moves by means of pseudopods and is well known as a representative unicellular organism. • Algae – a large and diverse group of plant like organisms ranging from unicellular to multicellular forms • Paramecium – consist of a single cell yet are visible to the naked eye

  6. Amoeba • Consists of a single cell • It is a consumer. It feeds on small plants, animals and bacteria • It lives in freshwater ponds (most likely to be found on the mud at the bottom)

  7. Structure of Amoeba Cell membrane Ectoplasm Cytoplasm Endoplasm Nucleus Waste products Pseudopod Fat Droplets Food Vacuole Contractile Vacuole

  8. Amoeba

  9. Structure of Amoeba • Cell membrane – semi-permeable • Cytoplasm divided up into • Endoplasm • Ectoplasm

  10. Endoplasm and ectoplasm Ectoplasm Endoplasm • The endoplasm is fluid-like. It has a grainy appearance due to the presence of food vacuoles and waste materials • Ectoplasm can become soft in places to allow the development of pseudopodia

  11. Development of Pseudopod • Pseudopods are referred to as ‘false feet’ as they are produced at any point on the body and have no fixed position • Pseudopodia extend in the direction Amoeba wishes to move

  12. Development of Pseudopod • Pseudopods develop when the ectoplasm softens and moves forward and the endoplasm moves in to replace it • Amoeba uses pseudopodia to engulf its prey

  13. Endoplasm and ectoplasm Before After

  14. Food vacuoles • Amoeba feeds by surrounding its prey with pseudopodia and secreting digestive enzymes into the vacuole created • Food can then be stored within the vacuole. Food vacuole

  15. Food vacuoles

  16. The Contractile Vacuole Amoeba’s cytoplasm is more concentrated than the surrounding fresh water High sugar/salt concentration Low sugar/salt concentration

  17. The Contractile Vacuole As a result water constantly rushes in by osmosis High sugar/salt concentration Low sugar/salt concentration

  18. The Contractile Vacuole In order to deal with this uptake of water Amoeba forms a contractile vacuole Excess water enters the contractile vacuole

  19. The Contractile Vacuole The contractile vacuole swells with water and moves to the edge of the cell…

  20. The Contractile Vacuole The contractile vacuole swells with water and moves to the edge of the cell…

  21. The Contractile Vacuole The contractile vacuole swells with water and moves to the edge of the cell…

  22. The Contractile Vacuole Where it bursts and expels the water…

  23. The Contractile Vacuole Where it bursts and expels the water…

  24. The Contractile Vacuole Where it bursts and expels the water…

  25. The Contractile Vacuole Where it bursts and expels the water…

  26. The Contractile Vacuole The cycle is then repeated

  27. Contractile vacuole • The contractile vacuole is said to be responsible for osmo-regulation • Without it the Amoeba would expand and burst

  28. Contractile vacuole bursting

  29. Learning Check • Name the structures present within the Amoeba cell • Outline the role of the contractile vacuole in osmoregulation

  30. Reproduction Asexual reproduction in amoeba takes place by Binary Fission. The amoeba cell divides by mitosis to form two amoeba cells.

  31. Sensitivity Amoeba respond to light, touch and chemicals.

  32. Gas Exchange in Amoeba Oxygen passes from water into the amoeba cell by diffusion. Carbon dioxide passes out of the cell into the water by diffusion.

  33. Diseases caused by Amoeba One species of amoeba is a parasite that causes a disease called amoeboid dysentery The infection is spread by contaminated (dirty) water The main symptom is mild to severe diarrhoea.

  34. Syllabus Can you answer the following questions?

  35. Depth of treatment • Amoeba – describe the cell organisation to include nucleus and sub-cellular structures

More Related