Biology 103 - Main points/Questions Remember how plants and animals reproduce? What else makes plants special What is different about the fungi? Are growth and development the same thing?

Remember Animal life cycles: Meiosis produces Gametes fertilize to make a This undergoes to produce a . Few animals have asexual reproduction exclusively

Remember Animal life cycles: Meiosis produces gametes (haploid) Gametes fertilize to make a diploid zygote Zygote undergoes mitosis to produce a multicellular diploid organism. Few animals have asexual reproduction exclusively

Fig. 10.3.b

Remember plant life cycles: Meiosis produces Haploid divide (mitosis) to make haploid a(n) _____ plant This produces – specialized haploid sex cells (like animals) These fuse (called ) to make a (grows into an embryo)

Remember plant life cycles: Meiosis produces spores Haploid spores divide (mitosis) to make haploid a “gametophyte” plant Gametophytes produce gametes – specialized haploid sex cells (like animals) These gametes fuse (fertilization) to make a zygote (grows into an embryo)

What is a Plant? Some characteristics: Plants are multicellular eukaryotes. Plants are autotrophic Plants alternate multicellular haploid and multicellular diploid generations What does that mean?

Plants: Alternate haploid and diploid stages Each is multicellular Different groups have different stages that are most common.

More Plant characteristics Plants have embryos that are dependent on a mature plant for nutrition Plant cells have cellulose cell walls that provide structural support.

More Plant characteristics Special adaptations for life on land Most have special transport tissues/structures (roots, vascular tissue…) Can team up with fungi to absorb nutrients (mycorrhizae) Waxy cuticle (slows water loss) & Stomata (allows gas exchange)

More Plant characteristics Fig. 22.2.b More Plant characteristics

Subcategories of Plants: The plant kingdom has many subdivisions we will talk mostly about four: Mosses – some of the most primitive land plants, lack vascular tissue, dominant gametophyte Ferns – seedless vascular plants

More subcategories Conifers/gymnosperms – plants with seeds but without flowers and fruit Flowering plants (angiosperms) – plants with flowers and fruit for reproduction

Last Kingdom to focus on is Fungus Lots of different types we will focus on one – the group that includes the gilled mushrooms you are most familiar with Like other groups most fungi use sexual reproduction at least some of the time.

What is an Fungus? Four criteria describe the Fungi. Fungal cells have a cell wall of chitin (of course still have membrane!) Fungi are heterotrophic eukaryotes Fungi secrete exo-enzymes that digest macromolecules outside their bodies. They then absorb the smaller subunits - causing them to be called absorptive heterotrophs.

(3) Fungal cells are usually form long thread-like filaments called hyphae The body of a majority of fungi is a complex mat of these hyphae called a mycellium Mushrooms are only a small part of the body of a fungus

Mass of hyphae – called a mycelium the mycelium is the main “body” of the organism the mycelium usually contains several meters of hyphae Figure: 20-1 part a Title: The filamentous body of a fungus part a Caption: (a) A fungal mycelium spreads over decaying vegetation. The mycelium is composed of (b) a tangle of microscopic hyphae, only one cell thick, portrayed in cross section (c) to show their internal organization. Question Which features of a fungus's body structure are adaptations related to its method of acquiring nutrients?

Individual hypha each hypha is basically a long string of cells Mitosis generates new cells Figure: 20-1 part b Title: The filamentous body of a fungus part b Caption: (a) A fungal mycelium spreads over decaying vegetation. The mycelium is composed of (b) a tangle of microscopic hyphae, only one cell thick, portrayed in cross section (c) to show their internal organization. Question Which features of a fungus's body structure are adaptations related to its method of acquiring nutrients?

cells communicate through gaps in wall called septa (singular, septum) cytoplasm can flow freely among the cells of the hypha 2 haploid nuclei often in a single cell (= dikaryotic) cell wall cytoplasm Figure: 20-1 part c Title: The filamentous body of a fungus part c Caption: (a) A fungal mycelium spreads over decaying vegetation. The mycelium is composed of (b) a tangle of microscopic hyphae, only one cell thick, portrayed in cross section (c) to show their internal organization. Question Which features of a fungus's body structure are adaptations related to its method of acquiring nutrients? pore septum two haploid nuclei

Septum and pore between cells

(4) Fungal life cycles are dominated by a haploid phase that grows from a haploid spore by mitosis. Most fungi reproduce both sexually and asexually Fungal life cycles are distinctly different from plants an animals

Fungal Life Cycle Terminology: Haploid v. Diploid Dikaryotic Spore Mating type

Sexual reproduction in Fungi Haploid Spore Mitosis Meiosis Cells Fuse Mitosis Dikaryotic Cell

Fungal life cycles main ideas: Meiosis produces spores Haploid spores divide (mitosis) to make haploid mycelium Any cell can fuse with a cell of another mating type (no specialized gametes!) Cytoplasm joins but not nucleus at first (dikaryotic cell!)

Fig. 21.8.a

Some fungi have very long-lived dikaryotic mycelia These are reproductive structures of mycelium that may be huge Some spread over 3.4 square miles and may be 2500 years old.

Fig. 21.12

Fairy Rings A ring of mushrooms may appear overnight. These are the reproductive structures of an underground mycelium (grown from a spore) As the mycelium grows out, it decomposes the organic matter in the soil and mushrooms form just behind this advancing edge.

Growth vs. Development These fairy rings help illustrate the difference between growth and development What do you think is the difference? The mycellium is growing through the soil but it is only when conditions are right that the fungus triggers the development of mushrooms.

Growth vs. Development Growth occurs as Cells divide Cells increase in size Development occurs as cells alter gene expression (cell differentiation) Plants and Animals use different strategies

Plant and Animal development patterns Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

Plant Growth & Development In flowering plants we still see haploid (gametophyte) and diploid (sporophyte) stages. Main plant is sporophyte Gametophyte is retained by sporophyte Looking at the development of embryo First look at flowers

Fig. 22.17.a

Stamen is both filament Fig. 22.17.a Stamen is both filament

sepal petal stigma anthers style Figure: 25-4 part b Title: A complete flower part b Caption: (b) The amaryllis is a complete monocot flower, with three sepals (virtually identical to the petals), three petals, six stamens, and three carpels (fused into a single structure). The anthers are well below the stigma, making self-pollination difficult. style

Plant Growth & Development In flowers the sporophyte generation gives rise to the gametophyte in two different places Male gametophyte produced in Anthers Female gametophyte is produced in Ovule Lets see how…

Male gametophytes are produced in the anther… Meiosis occurs and produces microspores These undergo mitosis to produce pollen (the male gametophyte)

Female gametophytes are produced in the ovule (inside an ovary)… Meiosis occurs and produces a megaspore

The megaspore undergoes meiosis to produce an embryo sac (the female gametophyte)

mature pollen sperm cells (n) tube cell nucleus stigma sperm style Figure: 25-10 Title: Pollination and fertilization of a flower Caption: Question How does double fertilization prevent plants from wasting energy? ovary integuments egg (n) polar nuclei within central cell

Development into an embryo

What about animal embryos – do we all have shelled eggs?

Reproduction & Development In most, a small flagellated sperm fertilizes a larger, nonmotile egg to make a zygote The zygote undergoes cleavage (mitosis), forming a hollow ball of cells called the blastula.

Some cells of the blastula then “crawl” inside (gastrulation) This forms a gastrula with 2 tissue layers and an opening (the blastopore!)

Gastrulation produces three tissue layers Occurs after implantation in humans (and other placental mammals) The placenta provides continuous nutrition during development instead of stored yolk

Tissues specialize to become... Three tissues are: Ectoderm (outside) Mesoderm (middle) Endoderm (inside) Tissues specialize to become...

Tissues specialize to become... Three tissues are: Ectoderm (outside) Mesoderm (middle) Endoderm (inside) Tissues specialize to become...

Protostomes and Deuterostomes there are two major kinds of animals representing two distinct evolutionary lines protostomes the mouth develops from or near the blastopore deuterostomes the anus forms from or near the blastopore; the mouth forms on another part of the blastula

Figure 25.34 Embryonic development in protostomes and deuterostomes.

Protostomes and Deuterostomes deuterostomes also differ from protostomes in three other fundamental ways the pattern of cleavage protostomes have spiral cleavage while deuterostomes have radial cleavage fating of cells it occurs later in deuterostome cleavage than in protostome cleavage origin of the coelom

Biology 103 - Main points/Questions Remember how humans reproduce? What makes an organism an animal & how do we subdivide the animal kingdom? What are some other animal reproductive strategies? What is different about the fungi?