Domain: Eukarya Kindom: PlantaeSummary from last lecture:-Prokaryotes gave rise to Eukaryotes ~ 2.5 billion years ago-Infolding of the prokaryotic cell membranes led to the formation of the nucleus, endoplasmic reticulum, golgi, lysosome.-Host prokaryotic cell was an Archaebacteria which gave rise to basic gene function (replication, transcription, translation)-Bacteria gave rise to mitochondria & chloroplasts (&flagella?). Bacterial genes run the basic maintenance and metabolic activities.Who are the plants?- Eukaryotic - Multicellular- Photosynthetic- Green algae (Liverworts, closest ancestor of land plants) ->Bryophytes (non vascular)Green algae -> Tracheophytes (vascular) -> Angiosperms (seeds in flowers and fruit)Chara – (Liverworts) class of filamentous green algae exemplified by the genus chara, in which the mitotic spindle is not surrounded by a nuclear envelope. Probably the closest relatives, among the algae, to higher plants. The giant internodal cells (up to 5cm long) exhibit dramatic cyclosis and have been much used for studies on ion transport and cytoplasmic streaming. Homosporous Life Cycle (Bryophytes & Ferns)Origin of Land Plants?1. DNA2. Chlorophylls A&B3. True starch inside chloroplasts4. Diverse life cycles & reproductiona. Asexual & sexual phasesb. Haploid & diploid stages5. Unicellular & multicelluar speciesImportant Characteristics of PlantsPresence or absence of vascular tissue (specialized cells that conduct fluids and nutrients from place to place in the organism)- Bryophytes (mosses, liverworts, hornworts) – lack vascular tissue (small)- Haploid (gametophyte) generation is dominant in bryophytes- Tracheophytes (ferns and seed plants) – have vascular tissue (can be large)-contain gymnosperms and angiosperms - Diploid (sporophyte) Dominant- Tracheophytes without seeds contain: Wisk ferns, Horsetails, Club mosses, & Ferns- Xylem – cells specialized to carry water and minerals (inner ring)- Phloem – cells specialized to carry water and sugar (outer ring)- Gametangia – gamete producing organs- Antheridium (Male) – swimming sperm- Archegonium (Female) – Eggs Plant Life Cycles3 Challenges to living on land1. Body dries out (desiccation)2. Gravity collapses large organisms3. Gametes dry out and may not disperse properlyHow do they overcome these challenges?1. Living in moist environments and being able to become dormant whenconditions are dry.2. They are dependent upon moist conditions for reproduction because theyhave swimming sperm but they are aided by rain, mist, and fog, and byanimal transport of sperm.3. Their dispersal over wide areas depends upon spores carried by the windof animals.How do sperm get to egg?1. 50% of moss species have different male and female plants that maybeseveral feet apart.2. Fertilization of moss shoots by mites and springtails.Fern Life Cycle (Life Cycle C) -
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