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Evolution of multicellular plants

Evolution of multicellular plants. Evolution of a multicellular organism from a unicellular protist. Fig 16.27. Going from unicellular to multicellular. Going from unicellular to multicellular. Advantages. Organization and specialization of plant parts.

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Evolution of multicellular plants

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  1. Evolution of multicellular plants

  2. Evolution of a multicellular organism from a unicellular protist Fig 16.27

  3. Going from unicellular to multicellular Going from unicellular to multicellular Advantages Organization and specialization of plant parts Permanent colonization of land becomes possible Disadvantages Loss of mobility – evolution of specialized plant parts is essential for nutrition and reproduction Reduction in individual plant growth rate Challenges “Communication” between cells The development of tissue systems

  4. Photos of slime moulds Photos of slime moulds by Clive Shirley Organisms with both unicellular and multicellular stages http://www.hiddenforest.co.nz/slime/intro.htm

  5. Slime moulds have structural adaptations Slime moulds have structural adaptations and life cycles that enhance their ecological role as decomposers Two main groups. 1 - Plasmodial slime moulds or true slime moulds, are a large single-celled mass with thousands of nuclei called a plasmodium formed when individual flagellated cells swarm together and fuse into one large bag of cytoplasm with many diploid nuclei. 2 - Cellular slime moulds spend most of their lives as separate single-celled amoeboid protists, but upon the release of a chemical signal, individual cells aggregate into a great swarm, known as a pseudoplasmodia and eventually muticellular slugs. http://www.wvonline.com/myxo/intro.htm

  6. The life cycle of a cellular slime mold, Dictyostelium The life cycle of a cellular slime mold, Dictyostelium

  7. Film of Dictyostelium

  8. Characteristics of Dictyostelium Dictyostelium amoebae grow as separate, independent cells but interact to form multicellular structures when challenged by adverse conditions such as starvation. Up to 100,000 cells signal each other by releasing a chemo-attractant and aggregate to form a mound. Subsequent processes depend on cell-cell communication. Many of the underlying molecular and cellular processes appear to have arisen in primitive precursor cells and to have remained fundamentally unchanged throughout evolution. Basic processes of development such as differential cell sorting, pattern formation, stimulus-induced gene expression, and cell-type regulation are common to Dictyostelium and metazoans. A model organism for bio-medical research.

  9. Alternation of Generations Alternation of Generations

  10. Origin of alternation of generations?

  11. Sizes and morphology of generations Relative sizes and general morphology of gametophyte and sporophyte generations in bryophytes, ferns and seed plants

  12. The life cycle of Ulva The life cycle of Ulva Fig 16.26C

  13. Evolution of a multicellular organism from a unicellular protist Fig 16.27

  14. Sections you need to have read 16.21 16.22 16.23 16.24 16.25 16.26 16.27 16.28 Courses that deal with this topic MICROM 435 Microbial Ecology

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