Algae- Plant- like Protists

Textbook 17.4pp. 390-394

Plant –like Protists- AlgaeAutotrophs-

Photosynthetic- chloroplasts-supply O2

Classified by: Type of cell wall Pigments Structure Storage carbohydrates

Reproduce asexually and sexuallyMost are unicellular; some are colonial and multicellular

Euglena

EuglenoidsSingle celledPhotosyntheticOne or two flagellaLack cell wallLive in freshwaterExample- Euglena- can be both an autotroph and a heterotroph.

B. DinoflagellatesSingle-celled; found in fresh and salt water.Cellulose cell wall.Two flagella.Plankton- surface of ponds, lakes, oceans

Serve as basis of aquatic food chains. Phytoplankton- photosynthetic Zooplankton- non-photosynthetic protozoans

Algae blooms- population explosion due to excess nitrates.

Red tidesToxins deadly to fish and humansPfiesteria- bleeding sores in fish; neurotoxin affects humans

Bioluminescent- some produce light.

C. DiatomsSingle-celled algae found in fresh & salt water.Glass-like cell wall of silica-

Many different refractile shapes

All contain chlorophyll; but other pigmentsMany colors of brown or yellow.

Impt. Food source for marine animals.Float near the surface- oil reserves.

When diatoms die; sink and fossil remains- diatomaceous earth are mined.Uses- grinding/polishing products, filter materials, toothpaste.

D. SeaweedsLarge multicellular algaeNot plants- No true roots,stems, or leaves.All have chlorophyll.3 groups based on pigments/ color.

Brown algae- Kelp- biggest- up to 60 m.Red algae- tropical- deepest waters; 1 type=agar.Green algae- evolutionary ancestor of plants.

Single- celled- Chlamydomonas with 2 flagella Colonial- Volvox ( 100-1000s of cells moving in

unison) Multicellular- filaments- Oedogonium, Spirogyra

Seaweed Uses-

Fungus-like Protists

Textbook 17.3pp.387-389

Fungus-like Protists A. Slime “molds”

Not true molds which are fungi

Decompose dead organic mater

2 types:

Plasmodial Slime Molds-

Cellular Slime Molds

1. Plasmodial Slime MoldsPlasmodium- mass of cytoplasm ,no membranes , no cell walls, many nuclei.Giant supercell ,streaming cytoplasm – amoeba like.Life Cycle-Limited resources- reproductive

structures- fruiting bodies (sporangia) formed.

Sporangia release haploid spores.Better conditions- haploid spores fuse

into diploid zygote.New plasmodium develops.

2. Cellular Slime Molds

Unicellular and Multicellular stages

Individual, colony, and spore stages.

Asexual and Sexual reproduction.

Scarce food- cells stick together

Slug-like colony

Trail of slime

B. Water molds- Oomycota

Freshwater.

Decomposed dead plants,animals.

Parasitic forms- skin or gills of fish.

Unicellular or multicellular

Sexual reproduction- egg cell

Downy moldsReproduce sexually- egg cellSpores- wind blownPlant parasites

Irish potato famine –mid 1800sExample of effects of clonesLack of genetic variation

Water and Downy molds-DNA studiesMore closely related to plant-like protists (algae)

Evolution

Textbook 17.5pp. 395-397

Evolution hypothesis

Protists evolved from ancient prokaryotes

Animals, Plants, and Fungi evolved from animal-like, plant-like, and fungus-like protists

2 main processes-explain complex eukaryotic cell.

Infolding

Endosymbiosis

Infolding:Inward folding of cell membrane of bacterial cellsProduced internal membranes of eukaryotic cells:

nuclear membrane, endoplasmic reticulum, golgi apparatus.

Eukaryotic Cell- separate compartments for chemical reactions.

Endosymbiosis:Explains mitochondria & chloroplasts

Phagocytosis of smaller bacteria into a host cell resulting in a symbiotic relationship.

Mitochondria- engulfment of aerobic bacteria.

Chloroplasts- engulfment of photosynthetic bacteria.

Evidence- Mitochondria & chloroplasts are similar to bacteria

Contain DNA, RNA & ribosomes.

Replicate their DNA and reproduce by binary fission.

Giardia have no mitochondria.