CHAPTERS 16 & 17: PROKARYOTES, FUNGI, AND

PLANTSHonors Biology 2012

PROKARYOTES• Lived alone on Earth for over 1 billion years

• Most numerous and widespread organisms (total biomass of prokaryotes is ten times that of eukaryotes)

• Live in cold, hot, salty, acidic, and alkaline habitats

• Some are pathogenic (most are benign or beneficial)

• Two domains: Bacteria and Archaea

• Archaea and Eukarya evolved from a common ancestor

PROKARYOTES• Cell walls maintain shape, provide

protection, and prevent lysis in a hypotonic environment

• Cell wall differences can be distinguished by gram stain

• Gram-positive have simple walls with a thick layer of peptidoglycan

• Gram-negative have complex cell walls with less peptidoglycan and an outer membrane of lipids bonded to carbohydrates

Fig. 16.4

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2

3

PROKARYOTES• Use pili to stick to

substrate

• Flagella allow movement response to chemical and physical signals

• Endospores - thick protective coat that can dehydrate and is tolerant of extreme heat and cold

• Endotoxins vs. exotoxins

• Bioremediation

Liquid wastes

Rotating spray arm

Outflow

Rock bed coated with aerobic bacteria and fungi

Fig. 16.10

PROTISTS• Obtain nutrition in a variety of ways (autotrophs, heterotrophs, and

absorption)

• Symbiosis - close association between organisms of two or more species

Nucleus

Primary endosymbiosis

Cyanobacterium

Heterotrophic eukaryote

Evolved into chloroplast

Autotrophic eukaryotes

Nucleus

Nucleus Chloroplast

Green alga

Chloroplast Red alga

Heterotrophic eukaryotes

Secondary endosymbiosis

Secondary endosymbiosis

Remnant of green alga

Euglenozoans

Remnant of red alga

Dinoflagellates

Apicomplexans

Stramenopiles Fig. 16.12

PROTISTS• Euglenozoans - have a crystalline

rod of unknown function inside flagella (include heterotrophs, autotrophs, and pathogenic parasites)

• Dinoflagellates - marine and freshwater phytoplankton

• Ciliates - use cilia to move and feed

• Stramenopiles - named for “hairy” flagellum (usually paired with a “smooth” flagellum (ex. water molds, diatoms, and brown algae)

Fig, 16.15

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PROTISTS• Amoebas - move and

feed by pseudopodia

• Slime molds

• Plasmodium - amoebozoan that forms a plasmodium (multinucleate mass of cytoplasm)

• Cellular - when food is scarce form a slug-like aggregate

PROTISTS

• Red algae - soft-bodied

• Green algae - include both chlorophytes and charophytes (closest living relatives of land plants)

Volvox colonies

Chlamydomonas

ALGAE LIFE CYCLES

• Alteration of generations (hapliod gametophyte and diploid sporophyte)

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MULTICELLULARITY

Unicellular protist

Colony

1

Locomotor cells

Early multicellular organism with specialized, interdepen- dent cells

Food- synthesizing cells

2

Later organism that produces gametes

Somatic cells

Gamete

3

Fig. 16.21

PLANTS AND FUNGI

• Mycorrhizae - mutually beneficial associations of plant roots and fungi hyphae

• Fungi enabled plants to colonize land by helping them absorb water and other minerals and plants provided sugars to the fungi

TERRESTRIAL PLANTS• Defined by:

• Alteration of haploid and diploid generations

• Walled spores produced in sporangia

• Male and female gametangia

• Multicellular, dependent sporophyte embryos

• Challenges:

• Maintaining moisture within cells

• Obtaining resources from soil and air

• Supporting body in air

• Reproducing and dispersing without water

Flagellated sperm

Stem

Leaf

Fern Stomata; roots anchor plants, absorb water; lignified cell walls; vascular tissue; fertilization requires moisture

Roots

Moss Stomata only on sporophytes; primitive roots anchor plants, no lignin; no vascular tissue; fertilization requires moisture

Spores

Flagellated sperm

Leaf

Stem

Roots

Flagellated sperm

Vascular tissue

Key

Holdfast (anchors alga)

Alga Water supports alga. Whole alga performs photo- synthesis; absorbs water, CO2, and minerals from water.

Spores

Fig. 17.1

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MOSSES• Nonvascular plant

• Dominant gametophyte

• Produces eggs and sperm in gametangia

• Zygote develops within the gametangium into a mature sporophyte which remains attached to the gametophyte

• Meiosis occurs within the sporangia and haploid spores are released to develop into sporophytes

Male Haploid (n) Diploid (2n)

Key Gametophytes (n)

Female

Sperm (n)

Egg (n)

Fertilization

Female gametangium

1

1

2

Zygote (2n) Sporophyte (2n)

3 Mitosis and development

Sporangium

Stalk

4

Meiosis

Spores (n)

5 Mitosis and development

Fig. 17.2 & 17.4

FERNS

• Seedless vascular plants

• Like most plants have a dominant sporophyte and a small, inconspicuous gametophyte

• Sporangia develop on the underside of leaves of the sporophyte

• Formed most of the coal that exists today

Haploid (n) Diploid (2n)

Key

Gametophyte (n)

Sperm (n)

Egg (n)

Fertilization

Female gametangium (n)

1

2 Zygote (2n)

New sporophyte (2n)

Mitosis and development

Meiosis

3

4

Mature sporophyte

Clusters of sporangia

Mitosis and development

5

Spores (n)

CONIFEROUS TREES

• Pine cone holds all of the tree’s reproductive stages: spores, eggs, sperm, zygotes, and embryos

• Male gametophyte is the pollen grain

• Female gametophyte carry ovules in the scales of the cone

Sporangia produce spores; spores develop into pollen grains.

Spore mother cell (2n)

Meiosis

1

Sporangium (2n)

Scale

Integument Pollination

Ovule

Meiosis

2

3 Pollen grains (male gameto- phytes) (n)

Ovulate cone bears ovules.

Haploid (n) Diploid (2n)

Key

Mature sporophyte

Egg (n)

Fertilization

Female gametophyte (n) Male gametophyte

(pollen grain)

Sperm (n)

A haploid spore cell develops into female gametophyte, which makes eggs.

4

Pollen grows tube to egg and makes and releases sperm.

5

Seed coat

Zygote (2n)

Zygote develops into embryo, and ovule becomes seed.

6

Food supply

Embryo (2n) Seed

7 Seed germinates, and embryo grows into seedling.

Fig. 17.7

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ANGIOSPERMS• Flowers contain male and

female gametophytes

• Stamen - include the anther where pollen is released

• Carpel - female reproductive structure that includes the ovary

• Ovules develop into seeds and the ovary matures into fruit

Meiosis

1

Haploid (n) Diploid (2n)

Key

Egg (n)

Fertilization

Sperm

Seed coat

Zygote (2n)

Food supply

Embryo (2n)

Seeds

Haploid spores in anthers develop into pollen grains: male gametophytes.

2

Meiosis

Pollen grains (n)

Ovule

Haploid spore in each ovule develops into female gameto- phyte, which produces an egg.

3 Pollination and growth of pollen tube

Stigma Pollen grain Pollen tube

4

Fruit (mature ovary)

6

Seed 5

Ovary Ovule

Stigma Anther

Sporophyte (2n)

Seed germinates, and embryo grows into plant.

7

Fig. 17.9

FUNGI• Absorptive heterotrophic

eukaryotes

• Most contain a mass of threadlike hyphae that make up a mycelium

• Have cell walls made of chitin

• Cause most plant diseases

Hypha

Mycelium

Fusion of cytoplasm

Heterokaryotic stage

Spore-producing structures

Asexual reproduction

Spores (n)

Diploid (2n)

Haploid (n)

Heterokaryotic (n + n) (unfused nuclei)

Key

Sexual reproduction

Zygote (2n)

Fusion of nuclei

Spore-producing structures

Spores (n)

Mycelium

Meiosis

Germination Germination

Figs. 17.14 & 17.15

FUNGI

Diploid (2n)

Haploid (n) Heterokaryotic (n + n)

Key

Fusion of two hyphae of different mating types

1 Growth of heterokaryotic mycelium

2

Mushroom

Diploid nuclei 3 Fusion of

nuclei

Basidia

Meiosis

Haploid nuclei

Spores released

4

Spores (n)

Germination of spores and growth of mycelia

5

Fig. 17.17

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