2 The Organism as a Unit of Life Looking Back at Bio 115The Organism as a Unit of LifeCellular Structure (cell = unit of life)…one or many!Metabolism = Homeostasis (PSN, Resp, N2fix, ferment, etc.)Growth = irreversible change in sizeReproduction…failure = extinctionAcclimatization-short term responses = behaviorAdaptation-long term responses = evolution
4 How Many Kingdoms? Extant 8 5 3 Extinct 2 Long Time with 1 ArchaebacteriaArchezoansMulticellular AnimalsProtozoansBryophytesSlime MoldsMyxozoansTrue FungiBacteriaEuglenoidsChrysophytesBrown AlgaeRed algaeGreen AlgaeTracheophytesKingdom Plantae is a clade853Extinct21Long Time withProkaryotes onlyOriginal Cell
5 Plants as a Clade Photosynthetic Organisms: Unifying features Cellulose walls glued together with pectinChlorophyll a and b, xanthophylls, carotenoidsStore starchStandard plant chloroplasts, mitochondria, golgi, etc.Most have Diplohaplontic (sporic) life historyMost have Oogamous gametes
7 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.
8 Life Cycle of Chlamydomonas SYNGAMYzygoteSporophyteGametophytesporangiumsporocytesporesgametangiagametesgerminationmitosisdifferentiation1N2NMEIOSISis it gametic?(diplontic)definitely zygotic(haplontic)
10 Some species of Ulva are anisogamous. Ulva life cycleThere are three isomorphic thalli:syngamyisogameteszygoteSome species of Ulva are anisogamous.+–settles on substrate1N2N+–GametophytesSporophytesettle on substrateholdfast+–Since they are motile, they are also called zoospores.meiosissporocyteThe life cycle is:√The meiospores made by the sporophyte are of two mating types.sporic: diplohaplonticgametic: diplonticzygotic: haplontic
16 OedogoniumThis is the zoospore, or maybe it is the sperm. Both have the same look!When both oogonium and antheridium appear on the same filament the alga is homothallic.
17 Oedogonium Life CycleSince antheridia and oogonia are on the same filaments, this species is homothallic.syngamyspermzygote (hypnospore)(in oogonium)empty antheridia1N2Negg(in oogonium)chemotaxisVegetative zoospores can clone the gametophyteThe zygote divides meiotically to release 4 zoospores.Zoospores settle down with a holdfast and grow into a filament.meiosisThis life cycle is haplontic (zygotic).