Lecture 4

							                                                 Lecture 5
                                                 Algae II


Chpt 17: 335-340

Sixth edition reading – 396-398 (not as good as 7th edition)

Great moments in evolution – transition to land…

1.   Chlorophyta (Green Algae)-

        17,000 species
        Unicellular and multicellular
        Aquatic and in moist terrestrial habitats
        Chlorophyll a and b
        Storage = starch inside chloroplasts
        Cellulose with hemicellulose, pectins
        Zygotic and sporic meiosis in those we are considering.

2. What was required for algae to leave the water and colonize land? What links might we look for
between specific algal groups and land plants?

3. Cellulose, hemicellulose, pectin

4. Starch stored in plastids

5. Chlorphylls a and b

6. Sporopollenin precursors – resist desiccation in spore walls

7. Cuticle precursors – protect vegetative structures from desiccation

8. Phragmoplast

9. Key connections to land plants… Green Algae

            Cellulose, hemicellulose, pectin
            Starch in plastids
            Chlorophylls a and b
            Sporopollenin precursors
            Cuticle precursors (waxes)
            Phragmoplast
            Zygotic meiosis (zygote is the only diploid cell)


10. Phylogenetic Tree – reminder of relationships

11. Phylogenetic tree focusing on the green algae and land plants
12. Multicellular gametophyte, egg retention, phragmoplast

13. Coleochaete

14. Encasement of the egg on the gametophyte and sporopollenin around the zygote!

15. Charales –

16. Conclusions

        Algae are a mixed assemblage representing amazing diversity.
        Current evidence clearly links green algae to the origin of land plants
        Among green algae Charales are the closest relatives to the land plants.
        Charales have many of attributes that were modified in modern land plants
        Remember the key topics… life cycles, water relations, etc.
17. coming to theatre near you… land plants
                                                                          Coleochaetales
                     Volvox, Ulvaceae, etc
      Chlorophytes



                                                 Mesostigma




                                                                                               Charales




                                                                                                                       Land Plants




                                                                                                          Tuesday’s Lecture…


                                                                                           Encasement of the egg on the gametophyte


                                                                 Multicellular gametophyte, phragmoplast, retention of the egg




                                                                                                          Simplifed 15-54
                                      Chlorphyll b, starch storage in chloroplast,