Plant-Like Protists

1. Plant-Like Protists Biology 112

2. Algae • Plant-like protists • Contain chlorophyll and carry out photosynthesis • Many are highly mobile • Scientists often disagree with their placement, particularly those that are very similar to plants • There are 7 major phyla according to their cellular characteristics

3. Chlorophyll • One way of classifying algae is with the pigments it contains • Algae lives in water • There is limited light in this environment • Different types of chlorophyll (a, b, c) absorb different wavelengths of light • As a result, algae can use more than red and violet wavelengths of light

4. Accessory Pigments • Absorb light at different wavelengths than chlorophyll • These pigments also produce energy for the organism • They appear to be colours other than green

5. Phylum Euglenophyta (Euglenophytes) • Contain two flagella but no cell wall • Contain chloroplasts • Contain reddish pigment concentrated in one area – known as a eyespot • Heterotrophic when sunlight is unavailable • Contain a cell membrane called a pellicle • This allows them to crawl when they can’t swim

6. Phylum Chrysophyta (Chrysophytes) • Yellow-green algae and golden-brown • Contain bright yellow pigments as well as gold-coloured chloroplasts • Contain cell walls • Store oils instead of starch • Reproduce asexually and sexually

7. Phylum Bacillariophyta (Diatoms) • Most abundant and plentiful of algae • Produce thin cell walls rich in silicon, the main component of glass

8. Phylum Pyrrophyta (Dinoflagellates) • Half are photosynthetic, other half are heterotrophs • Contain two flagella • Reproduce asexually • Most are luminescent • Give off light when agitated

9. Ecology • Common in salt and fresh water • Some can cause serious problems • They are the basis of the food chain in aquatic environments • They are grouped with other marine organisms called phytoplankton (small aquatic living things at the bottom of oceans)

10. Algal Blooms • Algae grows abundantly where sewage is discharged • They help recycle waste materials into usable molecules • When a lot of sewage accumulates, so do algal populations • These are referred to as blooms • Algae eventually dies and depletes the water of oxygen

11. Phylum Rhodophyta (Red Algae) • Contain chlorophyll a and reddish accessory pigments called phycobilins (absorb blue light) • Can live deep in the ocean • Highly adaptable to different temperatures • Help in the formation of coral reefs

12. Phylum Phaeophyta (Brown Algae) • Contain chlorophyll a and c as well as brown pigment, fuocoxanthin • Dark yellow to brown colour • Largest and most complex of the algae • Mostly marine, cool coastal water • Kelp is the most common example • Rockweed or seaweed too

13. Phylum Chlorophyta (Green Algae) • Share many characteristics with plants • Photosynthetic pigments and cell wall composition • Found in fresh and salt water as well as moist land environments • Most live entire lives as single cells – unicellular although a few types are multicellular

14. Ecology of Algae • Major food source for organisms in oceans • Called the “grasses” of the seas • They produce much of the world’s oxygen • Rich in vitamin C and iron • Many of the products we use have algae in its ingredients