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Prokaryotic Conjugation Nucleoid - genome (pilus-forming genotype) Plasmid - small circular DNA Nucleoid - genome (not a pilus-forming genotype) Pilus x x Conjugation Parasexual process Involving partial recombination (just a plasmid) Cells separate Only one participant leaves changed Compare Fig. 12.0 Pg. 256

Prokaryotic Pornography? What is going on in this micrograph? Which of these is the pilus-forming individual? Is there evidence that the genes for pilus formation have been moved to the recipient? http://www.hollver.is/mat/hrammi/matsjuk/Image4.gif

Biology: What is Life? life study of Properties of Life Cellular Structure: the unit of life, one or many Metabolism: photosynthesis, respiration, fermentation, digestion, gas exchange, secretion, excretion, circulation--processing materials and energy Growth: cell enlargement, cell number Movement: intracellular, movement, locomotion Reproduction: avoid extinction at death Behavior: short term response to stimuli Evolution: long term adaptation

Syngamy is always a two step process: Plasmogamy - union of gamete cytoplasms (makes a dikaryotic…heterokaryotic cell) Karyogamy - union of the two gamete nuclei (makes a diploid cell) In many species, plasmogamy and karyogamy are separated by moments in time and so are often omitted from books. Among fungi, these two steps may be separated by much longer intervals, including centuries! The details of syngamy and meiosis help distinguish the three major groups of fungi.

Evolution of Gametes for Syngamy: Isogametes - Anisogametes - Oogametes + –

Unicellular Life Cycle Your book uses “fertilization” as a synonym for syngamy. That word is confusing and inaccurate…to refer to the union of gametes. Syngamy is clear and precise! No multicellular body: ever! SYNGAMY 1N 2N gametes zygote spores sporocyte MEIOSIS Syngamy and Meiosis are Compensating Processes But have very different Evolutionary Origins Syngamy evolved from Conjugation

Domain Eukarya Kingdom Plantae Phylum Chlorophyta Green Algae Domain Eukarya Kingdom Plantae Phylum Chlorophyta

Chlamydomonas flagella contractile vacuole eyespot cellulosic wall http://www.unap.cl/~cbrieba/common/chlamydomonas.jpg contractile vacuole mitochondria chloroplast eyespot cellulosic wall nucleus cell membrane cytosol starch pyrenoid http://universe-review.ca/I10-23-chlamydomonas.jpg

Chlamydomonas cells of opposite mating type join in syngamy to form a zygote which develops a thick wall as a hypnospore. Upon return to better conditions, the zygote undergoes meiosis and releases flagellated cells of both mating types. http://www.biology.wustl.edu/faculty/images/goodenoughcaption.jpg http://www.isis.de/members/~ralfwagner/Bilder/Chlamydomonas_spec_Zygote.jpg

Unicellular Life Cycle http://www.isis.de/members/~ralfwagner/Bilder/Chlamydomonas_spec_Zygote.jpg No multicellular body: ever! http://www.biology.wustl.edu/faculty/images/goodenoughcaption.jpg SYNGAMY 1N 2N gametes zygote http://www.isis.de/members/~ralfwagner/Bilder/Chlamydomonas_spec_Zygote.jpg spores sporocyte MEIOSIS http://www.unap.cl/~cbrieba/common/chlamydomonas.jpg

Multicellular Life Cycles Compare Figs. 30.15, 30.16 Pg. 641 No multicellular haploid: diplontic No multicellular diploid: haplontic SYNGAMY 1N 2N gametes zygote mitosis germination gametangia mitosis differentiation differentiation Gametophyte Sporophyte differentiation differentiation mitosis sporangium mitosis germination spores sporocyte MEIOSIS When both haploid and diploid multicellular bodies are formed the life cycle is diplohaplontic

Life Cycle Classifications Has a Multicellular Unicellular Haplontic Diplontic Diplohaplontic Haploid No Yes Diploid Example Chlamy-domonas

Ulva lactuca thallus A thallus is a plant-like multicellular body lacking any vascular tissue (xylem or phloem). http://bio59000.free.fr/Photosbio59000/Biovegetale/Algues/Ulva%20lactuca.gif

Some species of Ulva are anisogamous. Ulva life cycle There are three isomorphic thalli: syngamy isogametes zygote Some species of Ulva are anisogamous. + – settles on substrate 1N 2N + – Gametophytes Sporophyte settle on substrate holdfast + – Since they are motile, they are also called zoospores. meiosis sporocyte The life cycle is: √ The meiospores made by the sporophyte are of two mating types. diplohaplontic diplontic haplontic

Life Cycle Classifications Has a Multicellular Unicellular Haplontic Diplontic Diplohaplontic Haploid No Yes Diploid Example Chlamy-domonas Ulva

Codium http://massbay.mit.edu/exoticspecies/exoticmaps/images/codium_big.jpg

√ Codium Life Cycle The life cycle is: diplohaplontic diplontic syngamy √ zygote 1N 2N Sporophytes 2 sexes anisogametes holdfast sporangium meiosis sporocytes zoospores

Life Cycle Classifications Has a Multicellular Unicellular Haplontic Diplontic Diplohaplontic Haploid No Yes Diploid Example Chlamy-domonas Ulva Codium

Oedogonium thallus http://www.plingfactory.de/Science/GruKlaOeko/Teichleben/Algen/Oedogonium%20sp..jpg

Oogonium http://www.rbgsyd.nsw.gov.au/__data/page/1810/Oedogonium.gif

Oedogonium This is either the meiospore or the sperm in SEM. They are morphologically similar. http://www.biologie.uni-hamburg.de/b-online/fo44/18.jpg http://www.csupomona.edu/~jcclark/classes/bot125/resource/graphics/g/chl_oedogonium.jpg When both oogonium and antheridium appear on the same filament the alga is homothallic.

Oedogonium Life Cycle Since antheridia and oogonia are on the same filaments, this species is homothallic. syngamy sperm zygote (hypnospore) (in oogonium) empty antheridia 1N 2N egg (in oogonium) chemotaxis The zygote divides meiotically to release 4 zoospores. Zoospores settle down with a holdfast and grow into a filament. meiosis This life cycle is haplontic.

Life Cycle Classifications Has a Multicellular Unicellular Haplontic Diplontic Diplohaplontic Haploid No Yes Diploid Example Chlamy-domonas Codium Ulva Oedo-gonium Life Cycle Evolution: Sequence unclear: elaborations vs reductions? Multiple pathways in different groups?