11/03/2010 BIOL 3007 Lecture

by Gilbert Keith

Short blurb on coral bleaching.

Stramenophiles aka heterokonts (kont = flagellum.) Common theme: two flagella. One is tinseled, the other is whiplashed. Stramenophiles: straw, hairs. Hairs are tripartite.

They include the golden algae, the brown algae, the diatoms, and oomycota (a fungal group.)

/*this prof really loves the etymology of names, eh*/

Golden algae: chrysophyta. They like unpolluted waters. Mostly cold, freshwater dwelling.  Active during the winter. Won’t survive in warm conditions. They can cause toxic blooms. Can also influence the quality of water. They may be unicellular or colonial. Sitting in a cuplike protective structure: Similar to tricholomonas.

All stramenophiles have the same kind of pigments: chlorophylls a and c, as well as fucoxanthin. The fucoxanthin gives them a yellow colour. golden algae produce chrysolaminarin. They may have scales with silica or walls with cellulose.

Tinsel flagellum is longer than the whiplash flagellum. They have 3 types of hair: thin hair at the top, stouter hair in the middle which connects to a thicker hair at the bottom. The scales have silica.

They also produce cysts in the resting state. Cysts can be produced by asexual or sexual reproduction. THey begin to deposit the silica inside the cytoplasm. They make a bottle, and sit in the bottle. They make a plug, and unplug the bottle during germination.

DIATOMS:

Important components of phytoplankton. THey are both marine and freshwater organisms. THey are major contributors to photosynthesis. ~25% of global carbon is fixed  by diatoms. Important food source of many marine organisms. Their walls have silica and pectin (very distinctive.)

Colonial diatoms, can literally be unfolded or aggregate into starlike shapes. Many are single celled. Some are radially symmetric (Centric diatoms: mostly floating and planktonic), and others are bilaterally symmetric (mostly bottom dwelling on vegetation; little groove that runs through the shell to enable gliding motility.) The surfaces have all sorts of ribbing and sieve like components.

FRUSTULE: ONE PIECE BIGGER THAN THE OTHER. Overlapping halves. Asexual reproduction by mitosis. Formation of a membrane that lies between the two nuclei, made of silica. Makes two new BOTTOMS. They’d have to become smaller and smaller if they kept dividing that way…

/* I wonder if that’s gonna be on the test */

Gametic meiosis . Very large zygote called the auxospore is formed. Divides tor produce some very large cells, then goes through a cascade of shrinking down.

Perforation: solid glass wall would make them sink. Perforation helps them be lighter. Also promotes water and nutrient exchange. http://onlinelibrary.wiley.com/doi/10.1002/adfm.200700609/abstract

Diatomaceous earth: used to make filtered liquids, production of antibiotics, insulation, etc. Also yields geological information of  lakes and oceans. Slide on “Rock Snot

Brown algae: last group. They do not have any unicellular or multicellular forms. They are usually filamentous (morphologically complex thalli.) Diverse life histories. Grow best in cold water.

The storage products are a little different (laminarin instead of chrysolaminarin.) Ectocarpus is a simple brown alga. Alternation of generations (isomorphic.) They have different types of sporangia. Unilocular in which meiosis occurs to make haploid zoospores (germinate to make gametophytes) and plurilocular which has many chambers, and makes diploid asexual zoospores (motile.)

Fucus, conceptacles. diploid life cycle.

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