Biodiversity Unit 2 - Frazier

Ploidy

the number of sets of chromosomes in a cell

Haploid (n)

one set of chromosomes

Diploid (2n)

two sets of chromosomes in pairs

Mitosis

nuclear division which produces two cells of identical number of chromosomes

Cytokinesis

when the cytoplasms of a cell splits to make two separate cells

What does mitosis followed by cytokinesis create?

two identical daughter cells

Meiosis

diploid cell makes 4 genetically different haploid daughter cells

What organisms reproduce zygotically?

fungi, algae

What organisms reproduce gametically?

animals

What organisms reproduce sporically?

plants and some algae

How do fungi feed?

extracellular digestion and nutrient absorption

saprobe (decomposer)

breaks down dead organic material into simple organic compounds

Mutualism

interaction between two or more species in which both species benefit from the interaction

Lichens

algae/cyanobacteria living together with fungus (asco/basidiomycota)

Types of lichens

fruticose (shrub-like), foliose (leaf-like), crustose (crust-like)

Mycorrhizae

mutualistic relationship between fungi and plant roots that help a plant get nutrients

Commensalism

an interaction between two or more species where one benefits and the other is not affected

Parasitism

interaction between two or more species where one species is harmed while the other benefits

Fungi body structure

cell wall made of chitin, various ploidy of hyphae, fruiting body, mycelium

Septate hyphae

hyphae with cells divided by cell walls

Coenocytic hyphae

hyphae with no cell walls (multi-nucleated)

Haustorium hyphae

hyphae that inserts itself inside the host cell and injects haustorium (septate)

Fungi spend most of their life in which ploidy

haploid

Heterokaryotic (n+n)

fusion of two haploid hyphae

What is the ploidy in fungi asexual reproduction

Only haploid

When do spores germinate

when conditions are favorable

Plasmogamy

when the plasma membranes of hyphae fuse

Karyogamy

when genetically different nuclei within the same hyphae cell fuse

Generalized life cycle of fungi

Phylogeny of Fungi

Chytridiomycota, Zygomycota, Ascomycota, Basidiomycota

Phylum Chytridiomycota

- "chytrids"

- aquatic with flagellated zoospores

- possible ancestor of terrestrial multicellular fungi

- some are parasites of algae, plants, animals

- chytridimycosis - disease in frogs caused by a chytrid

Phylum Zygomycota

- "zygote fungi"

- mostly terrestrial

- spores dispersed by air

- coenocytic hyphae

- zygosporangia - fruiting body

- zygospores - sexual spores

- sporangiospores - asexual spores

- ex: rhizopus - black bread mold

Phylum Zygomycota Life Cycle

Asexual: Dispersal and germination of spores from sporangium, then it becomes mycelium and then back to the sporangia to produce more spores

Sexual: Dispersal and germination of spores from sporangium, then mating type (+) and mating type (-) connect and become gametangia with haploid nuclei, then plasmogamy to make young zygosporangium (heterokaryotic), then through karyogamy to make diploid nuclei, then through meiosis to start the process over again

Phylum Ascomycota

- "sac fungi"

- most diverse group

- live in marine, freshwater, or terrestrial environments

- free-living, parasites, or symbiotic

- unicellular (yeast) to large fungus

- spores dispersed by air

- ascus- spore producing structure (spore sac)

- ascocarp - fruiting body made of asci

- conidia - asexual spores

- conidiophore - specializes stalks that release conidia

Phylum Ascomycota Life Cycle

Asexual: Condidiophore disperses conidia (spores)and germinates to make mycelium, then cycle starts over

Sexual: Two genetically different mycelia (antheridium and ascogonium) undergo plasmogamy, then the antheridium's nuclei go into the ascogonium (like fertilization) and grows hyphae. A cell grows off from the hyphae called an ascus (n+n), which then undergoes karyogamy , forming a zygote (2n) that immediately undergoes meiosis to form 4 nuclei in the ascus. The 4 nuclei undergo mitosis and form eight ascospores, which are then dispersed and make mycelia

Asexual reproduction in ascomycetes

Asexual spore production, budding (yeast), hypha fragmentation

Budding

the pinching off of an offspring from the parent cell (yeast)

Hypha fragmentation

fragments of hyphae that can separate and grow into new colonies

Asexual spore formation

a haploid cell produces by mitosis from a haploid parent cell

Phylum Basidiomycota

- "club fungi"

- mushrooms, shelf fungi, puffballs, rusts

- major decomposers of wood (lignin)

- mycelia formed by haploid septate hyphae

- only sexual reproduction

- basidium - spore producing structure

- basidiocarp - fruiting body (dikaryotic mycelia)

Phylum Deuteromycota

- "imperfect fungi"

- septate hyphae

- sexual reproduction is absent

- only asexual reproduction through conidia (spores) on conidiophores (spore producing structures)

- ex: athlete's foot, ringworm

Phylum Basidiomycota Life Cycle

- only sexual

- two genetically different mycelia (n) undergo plasmogamy and form a dikaryotic mycelium (n+n), forming individual basidia that create a larger basidiocarp (fruiting body). The basidia undergo karyogamy to form a diploid nuclei (2n), then meiosis to form a basidium with four haploid nuclei. The basidium then releases basidiospores which are then dispersed and grow into mycelia (n)

Where did plants evolve from?

Phylum Chlorophyta (Kingdom protista), Class Charophycea

What do charophytes and land plants have in common?

Intracellular structures, structure of flagellated sperm, structures that synthesize cellulose, presence of chloroplasts, chlorophylls A and B

What life cycle type do plants have?

Sporic type

General Characteristics of Plants

- sporic life cycle

- multicellular

- photosynthetic autotrophs

- chlorophylls A and B

- monophyletic kingdom

- cellulose based cell wall

- reproduce by alternation of generations (gametophyte and sporophyte)

gametophyte

the phase in a plant life cycle where gametes are produced

sporophyte

the phase in a plant life cycle where spores are produced

Haploid spores are released and grow into...

haploid gametophytes

What does the diploid sporophyte produce?

haploid spores via meiosis

what does the haploid gametophyte produce?

haploid gametes via mitosis

Syngamy

fusion of gametes

Isogamy

sexual reproduction by the fusion of similar gametes

Anisogamy

sexual reproduction by the fusion of dissimilar gametes

Oogamy

sexual reproduction in which one of the gametes (the egg) is large and nonmotile and the other gamete (the sperm) is smaller and motile

Plants colonized land around

400 mya

Physical characteristics of plants

- root system

- conduction tissue

- cuticle (wax surface)

- stomata

- support tissue

- gametes protected within gametangia

- apical meristems

- starch storage

- chlorophylls A and B

Bryophytes

nonvascular plants

Characteristics of Bryophytes

- lack vascular tissue

- gametophyte is dominant

- sporophyte is ephemeral and dependent on the gametophyte

- have cuticle on their simple leaf-like structures

- found in moist areas

- flagellated sperm cells

- dependent on water for fertilization

- have rhizoids

- have a cuticle and stomata

cuticle

a waxy covering on leaves and stems that prevents water loss

stomata

pores on a leaf that allow for oxygen and carbon dioxide exchange

ephermeal

short-lived

rhizoids

root-like structures used for anchorage (not true roots)

Phylum Bryophyta

- "mosses"

- most advanced of the bryophytes

- have conducting cells (not tissues)

- have rhizoids

- have protonemata

- have cuticle and stomata

Phylum Bryophyta Life Cycle

spores are released from the sporangium, which then grow through mitosis into a protenemata, then a bud, and form a male and female gametophyte. The male gametophyte, called an antheridium, produces sperm. The female gametophyte, called an archegonium, produces eggs. The sperm fertilizes the egg in a raindrop within the archegonium. The zygote grows into an embryo, then a sporophyte with a sporangium on top. The sporangium undergoes meiosis and releases spores.

Phylum Hepatophyta

- "liverworts"

- simplest of all the bryophytes

- lack cuticle and stomata

- ex: marchantia

Phylum Anthocerophyta

- "hornworts"

- closely related to green algae

- have stomata

- tall, narrow sporophyte attached to gametophyte

Characteristics of seedless vascular plants

- have a vascular system made of xylem and phloem

- sporophyte is dominant stage

- gametophyte is ephemeral

- branching made possible for more sporangia to be produced

- sporangia are arranged in strobili

- posses true roots

- posses true leaves (mircophylls and megaphylls)

Xylem

vascular tissue that transports water and nutrients

Phloem

vascular tissue that moves sugars and hormone throughout the plant

Strobili

groups of sporophylls in cone-like, helical structures

Hypothesis for the evolution of leaves

Microphylls came from green tissue (photosynthetic cells) that experienced invaginations and made one "branch"

Megaphylls came from microphylls that continued to branch out and eventually began developing green tissues that evolved into leaves

Bisexual (in plants)

plants with both male and female reproductive structures

Monoecious

plant that contains male and female reproductive organism in one organism

Dioecious

contains male and female reproductive organs on separate organisms

Phylum Lycophyta

- "club mosses"

- extinct and extant species

- microphylls

- ephemerous gametophyte is unisexual or bisexual

- sporophyte is dominant

- sporphylls arranged in strobili

- Major group in forming coal

- ex: lycopodium, selaginella, isoetes

Phylum Sphenophyta

- "horse tails"

- extinct and extant species

- stems contain silica

- scale-like leaves and nodes

- may have separate vegetative and reproductive shoots

- bisexual ephemerous gametophyte

- sporophyte is dominant

- ex: equestrium

Phylum Psilophyta

- "whisk ferns"

- extinct and extant species

- no roots or leaves

- dichotomous (two) branching stems

- fused sporangia as the "yellow ball"

- sporophyte is dominant

- ephemerous gametophyte is bisexual

- "naked" seeds

- ex: psilotum

Phylum Pterodophyta

- "ferns"

- extinct and extant species

- possess roots, fronds (megaphylls), fiddleheads, and sori

- sporophyte is dominant

- emphermous gametophyte is mostly bisexual

sporangium

contains haploid spores that grow into gametophyte

antheridium

male sex organ which contains sperm

archegonium

female sex organ which contains eggs

Life Cycle of a Fern

Sporangia release spores, which develops into a bisexual photosynthetic gametophyte. Each gametophyte (archegonium - female; antheridium - sperm) releases gametes. The sperm fertilizes the egg within water (rain, soil, etc), forming a zygote. The zygote grows into a sporophyte on top of the gametophyte, and has sacs containing sporangium (sori), which release spores.

Homosporous spore production

sporangium in sporophyll --> single type of spore --> bisexual gametophyte --> eggs/sperm

Heterosporous spore production (female)

Megaporangium in megasporophyll --> megaspore --> female gametophyte --> egg

Heterosporous spore production (male)

Microsporangium in a microsporophyll --> microspores --> male gametophyte --> sperm

Gametophyte is dominant in

bryophytes only

Sporophyte is dependent on gametophyte in

bryophytes (nonvascular)

Sporophyte and gametophyte are independent of each other in

ferns (seedless vascular plants)

Gametophyte is dependent on sporophyte in

seed plants (gymnosperms, angiosperms)

Terrestrial Adaptations of Seed Plants

- reduced gametophytes (ovules and pollen grains) retained and protected in moist sporophytic reproductive tissue

- heterospory - male and female spores are produced in different structures

- Pollination

- The seed (mature fertilized ovule)

- Secondary compounds

seed development

Female gametophyte is fertilized by a male gametophyte and develops into a young sporophyte inside a seed coat made of integument

Gymnosperms

- "naked seeds"

- do not produce flowers

- seeds exposed within cone

Phylum Cycadophyta

- "cycads"

- 320 mya

- palm-like leaves

- highly toxic compounds

- reproduce through cones

- dioecious

- beetles are important pollinating agents

- Only North American cycad: coontie (releases cicasin, a toxic alkaloid)

Phylum Ginkgophyta

- Mostly extinct

- Only surviving species: Ginkgo biloba

- Fan-like leaves

- Dioecious

Phylum Gnetophyta

- has characteristics of both gymnosperms and angiosperms

- fleshy leaves

- strobili similar to some inflorescence

- 3 genera: gnetum (tropical), ephedra (Arizona), welwitschia (Africa)

Phylum Coniferophyta

- "conifers," "evergreens"

- oldest, tallest, largest trees

- needles adapted to drought conditions (dry winters)

- important for lumber, paper, etc.

- Ex: sequoia (redwood), pines, junipers, bald cypress,

Ovulate cone

-megastrobilus with megasporophylls (scales)

Staminate cone

microstrobilus with microsporophylls (pollen cones)

Sporogenesis

formation of spores