Bio 1B Fall 05 Lecture Outline Overview of Life Cycles Comparisons Professor Thomas Carlson Bio 1B Fall 05 Lecture Outline Overview of Life Cycles Comparisons Professor Thomas Carlson Life Cycles Overview Plant Group Comparisons Life cycle events that occur during lifespan of organism from conception to the reproduction of offspring Bio 1B Fall 05 Professor Thomas Carlson 1 Bio 1B Fall 05 Lecture Outline Overview of Life Cycles Comparisons Professor Thomas Carlson 2 Bio 1B Fall 05 Lecture Outline Overview of Life Cycles Comparisons Professor Thomas Carlson Diploid 2n Haploid 1n Contain two copies of each chromosome Haploid cells 1n contain one copy of each chromosome Haploid phase is a gametophyte Gametophytes produce gametes reproductive cells that must fuse into other gametes before growing into new diploid individuals 3 Diploid phase is a sporophyte Cells in the reproductive structure of the diploid sporophyte undergo meiosis produce haploid spores Spore is a reproductive cell that grows into a new individual directly through mitotic division 4 Bio 1B Fall 05 Lecture Outline Overview of Life Cycles Comparisons Professor Thomas Carlson Bio 1B Fall 05 Lecture Outline Overview of Life Cycles Comparisons Professor Thomas Carlson Alternation of Generations Figs 13 6b 29 5 Life cycles that involve Dikaryotic n n multicellular haploid stage gametophyte that produces gametes Cells in fungi with two separate haploid nuclei per cell and alternates with multicellular diploid stage sporophyte that produces spores 5 Bio 1B Fall 05 Lecture Outline Overview of Life Cycles Comparisons Professor Thomas Carlson 6 Bio 1B Fall 05 Lecture Outline Overview of Life Cycles Comparisons Professor Thomas Carlson Alternation of Generations Figs 13 6b 29 5 30 2 Haploid spores are produced by meiosis from diploid sporophyte Spores germinate and divide mitotically to produce a multicellular haploid gametophyte which produces gametes by mitosis Gametes are mature sexual reproductive cells produced by mitosis from haploid gametophyte Isomorphic alternation of generations the two haploid diploid generations look similar morphologically example is Ulva green algae Syngamy is when two gametes fuse Haploid organism diploid organism or both may also reproduce asexually 7 8 Bio 1B Fall 05 Lecture Outline Overview of Life Cycles Comparisons Professor Thomas Carlson Bio 1B Fall 05 Lecture Outline Overview of Life Cycles Comparisons Professor Thomas Carlson Heteromorphic alternation of generations the two generations differ morphologically with dominant haploid gametophyte phase Bryophytes liverworts hornworts mosses sporophyte is dependent on dominant gametophyte Fig 30 2 Heteromorphic alternation of generations with dominant diploid sporophyte phase Haploid gametophyte not dependent on sporophyte Brown algae kelp Laminaria Fig 28 21 Pteridophytes seedless tracheophytes Fig 29 14 Very reduced tiny short lived haploid gametophyte dependent on sporophyte Gymnosperms seed tracheophytes Fig 30 4 30 6 Angiosperms seed flower tracheophytes Figs 30 10 30 12 9 Bio 1B Fall 05 Lecture Outline Overview of Life Cycles Comparisons Professor Thomas Carlson 10 Bio 1B Fall 05 Lecture Outline Overview of Life Cycles Comparisons Professor Thomas Carlson Life cycles with Unicellular Phases Life cycles with Dikaryotic Phase Do Not Represent Alternation of Generations Do Not Represent Alternation of Generations Dominant Haploid gametophyte unicellular phase with unicellular zygotic diploid phase unicellular green algae e g Chlamydomonas Dominant dikaryotic sporophyte multicellular phase with small haploid gametophyte multicellular phase haploid phase NOT dependent on sporophyte for nutrition 11 some fungi Basidiomycota Ascomycota Fig 39 20 12 Bio 1B Fall 05 Lecture Outline Overview of Life Cycles Comparisons Professor Thomas Carlson Bio 1B Fall 05 Lecture Outline Overview of Life Cycles Comparisons Professor Thomas Carlson Comparison Algae Bryophytes Pteridophytes Gymnosperm Angiosperms Life cycle reproduction Life cycles reproduction haploid vs diploid dominant Haploid dominant bryophytes some green algae Fertilization strategy water vs wind vs animal vs Vascular tissue none vs tracheids vs vessels Diploid dominant pteridophytes gymnosperms angiosperms some brown algae e g kelp Macrocystis Laminaria Leaf type none vs microphylls vs megaphylls 13 Bio 1B Fall 05 Lecture Outline Overview of Life Cycles Comparisons Professor Thomas Carlson 14 Bio 1B Fall 05 Lecture Outline Overview of Life Cycles Comparisons Professor Thomas Carlson Fertilization strategies Leaf type water algae brypophytes pteridophytes No true leaves algae bryophytes vs wind microphyll small leaf with one vein gymnosperms angiosperms some pteridophytes e g lycopods vs megaphyll multiple veins in leaves often large leaves fern pteridophytes gymnosperms angiosperms animal angiosperms 15 16 Bio 1B Fall 05 Lecture Outline Overview of Life Cycles Comparisons Professor Thomas Carlson Bio 1B Fall 05 Lecture Outline Overview of Life Cycles Comparisons Professor Thomas Carlson Vascular Cell Types Vascular tissue none algae bryophytes except for some mosses with hydroids vs tracheids with lignin pteridophytes gymnosperms Vessels most advanced type of water conducting tissue in plants only found in gnetophytes and angiosperms vessel end wall gaps enable efficient water transport vs vessels with lignin some gnetophytes angiosperms 17 Bio 1B Fall 05 Lecture Outline Overview of Life Cycles Comparisons Professor Thomas Carlson tcarlson berkeley edu 11 11 03 Alternation of Generations Haploid Dominant Sporophyte dependent on gametophyte Water required for fertilization Independent sporophyte gametophyte Diploid Dominant Tracheids or vessels Heterosporous Gametophyte dependent on sporophyte Wind or animal fertilization Pollen Seeds Flowers Fruits Double Fertilization Triploid Endosperm Bryophytes X X X X Pteridophytes Gymnosperms Angiosperms X X X X X X X tracheids Aquatic ferns Tracheids elongated water conducting cells with primary cell wall cellulose may also contain secondary cell walls with deposits of lignin which could develop into wood to make tree growth possible X X X tracheids vessels X vessels tracheids X X X X X mainly wind X animals wind X X X X X X 19 18
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