Topic 10: Other Stramenopiles

Question 1

• Describe the general structure of an Ochromonas cell

Answer 1

Ovate cell with long flagella that has many microtubule hairs on it

Question 2

• What does the vegetative state of Dinobryon look like?

Answer 2

Tree-like colonial arrangement
Looks like a bunch of flagellated cells in a bunch like flowers

Question 3

Chrysophytes produce a characteristic resting stage or cyst. What is it called and what does it look like?

Answer 3

Stomatocyst: Also known as stratospores or siliceous cysts

This is a silica-walled round cyst with an elevated margin

Form from asexual or sexual reproduction

They have unsilificed region at apex that is plugged with polysaccharides

Stomatocyst formation is correlated to cell density

Question 4

What are the two genera of marine Raphidophyceans that are well known for producing harmful algal blooms (HABs)?

Answer 4

Chattonella is well known for this via the production of large amounts of reactive oxygen

Heterosigma produces large toxic blooms, and can be even be found in BC waters

Question 5

What critical accessory pigment that is present in diatoms and other stramenopiles is absent in Xanthophyceans ?

Answer 5

Fucoxanthin is not present in Xanthophyceans

Chloroplasts appear yellow or green

Question 6

Some species of Xanthophyceans are found as siphonaceous coenocytes. Describe this type of morphology.

Answer 6

The algae is comprised of a single large connected cell with many nuclei throughout
It is arranged in a long tube or siphon with a continuous column of cells