Dinophyta

Question 1

_____% of dinoflagellates are planktonic

Answer 1

90

Question 2

Dinoflagellates are included in the group ________

Why?

Answer 2

Alveolates

Presence of alveoli (membrane bound vehicle)

Question 3

Cell covering a of dinoflagellates

Answer 3

Continuous outermost membrane + single membranes bound thecal vesicles (alveoli)

Thecal vesicles contain little or no cellulose or thick cellulose plates (thecal plates)

Question 4

Amphiesma

Answer 4

Array of membranes and vesicles

Question 5

Dinoflagellate cell types distinguished by position of flagella:

Answer 5

Desmokont: flagella emerge apex
-both flagella inserted anteriorly

Dinokont: flagella emerge from mid point (ventrally inserted)
-both flagella are inserted centrally and lie in surficial grooves (whiplash and tinsel flagella)

Question 6

Typical dinokont cell types

Answer 6

Upper half: Epicone
Lower half: Hypocone

Transverse groove-encircles the cell: girdle

Sulcus: extends posteriorly in the hypocone from the cingulum

Question 7

Part of cell directed forward during swimming is considered to be ______

Answer 7

Anterior

Question 8

Region from which flagella emerge is considered _____

Answer 8

Ventral side

Question 9

Dinophyta vary in the number and arrangement of ______

Answer 9

Thecal plates

Question 10

Controversy of thecal plate arrangement

Answer 10

Was many thecal plates original to ancestor or was few???

Question 11

Dinoflagellates originated from ______ ancestors

Why is this supported

Answer 11

Heterotrophic (800mya)

Many dinoflagellates are heterotrophic today

Question 12

In the fossil record, _____% of dinoflagellates produce an organic layer of _______ beneath thecal plates

Answer 12

40

Dinosporin

Question 13

____% of dinoflagellates are __________
But most are _______

Answer 13

Photosynthetic (50%)

Mixitrophic

Question 14

Most photosynthetic dinoflagellates originated from _____ symbiosis with a ______ and therefore contain ______

Answer 14

Secondary
Red algae

Chlorophyll a and c as well as peridinin (carotenoid) and pyrenoids

Question 15

Plastid membranes of dinoflagellates

Answer 15

Two membranes of chloroplast envelope

One membrane of chloroplast e.r from primary host ebdosymbiont

Question 16

Tertiary endosymbiosis in dinoflagellates

Answer 16

1. Begins with a loss of a Plastid (originally deceived from a secondary endosymbiosis of red algae)
2. Followed by endosymbiosis of a diatom
3. Instead of peridinin pigment it has fucoxanthin pigments from diatom

Question 17

In Dinophyta, photosynthates are stored as _____

Answer 17

Cytoplasmic starch grains, lipids droplets, unsaturated fatty acids and sterols

Question 18

Some dinoflagellate sterols are linked to fossil _______

Answer 18

Oil deposits

Blooms contributed to oil deposits in areas with incomplete degradation of organic lipids

Question 19

In a dinoflagellate, where can you find lipid bodies and starch grains

Answer 19

Lipid-anterior end of cell

Starch-posterior end of cell

Question 20

Chromatic adaption

Answer 20

Dinophyta are able to capture and harvest more light by using water soluble peridinin-chlorophyll-protein light harvesting complex (PerCP) found in the lumen of plastids and membrane bound light harvesting complexes

Peridin absorbs in the blue-green range (450-550) which is beyond chlorophyll-A’s capability

More peridinin to chlorophyll is chromatic adaptation

Question 21

Dinophyta motility

Answer 21

-longitudinal flagellum (whiplash) projects out->speed and steeering

-transverse flagellum (tinsel) coiled and closest appressed and used for rotating

Great swimmers (200-500mm/sec)

Question 22

How are the flagellum arranged in dinophyta

Answer 22

9+2 array of microtubules

Question 23

What percent of dinoflagellates have an eyespot?
What does the eyespot do?

Answer 23

<5%

They are simple: lipid droplets packaged within membranes
Or
They are complex: rows of lipid globules

Contain carotenoids for phototaxis
-reposition longitudinal flagellum and swim towards light

Question 24

Do dinophyta have a flavin based light detector at the base of the flagella?

Answer 24

No

Question 25

Dinophyta Trichocysts

Answer 25

-defensive trichocysts: rod shaped crystalline, protein filaments -triggered by changes in temperature, turbulence, and other disturbance -discharged upon rapid hydration -discharge causes a jet-propulsive response to predators Or can be used to catch prey (nematocysts)

Question 26

Dinophyta reproduction

Answer 26

Asexual division of haploid, motile cells Sexual reproduction due to changes in nutrients, irradiance, photoperiod, temp -gametes resemble vegetative cells, syngamy is slow and difficult to distinguish from cell division, and often occurs at night. Making it hard to observe!!!! -early stages of zygote development have >2 flagella -formation of cysts often follow sexual reproduction and are viable for 100 years

Question 27

Photosynthetic _______ are second to diatoms as primary producers in costal waters

Answer 27

Dinoflagellates

Question 28

Zooxanthellae

Answer 28

Unarmoured marine dinoflagellates are marine symbionts of most reef bulking coral polyps

Question 29

“Bleaching”

Answer 29

When coral polyps expel their zooxanthellae and therefore their colour

Question 30

Zooxanthellae and coral exchange of nutrients

Answer 30

Coral gets plenty of carbon from zooxanthellae Zooxanthellae get carbon dioxide from coral

Question 31

Dinoflagellates were once called what? Why?

Answer 31

Pyrrhophyta (fire plants) Some species are bioluminescent

Question 32

Adaptation to bioluminescence

Answer 32

Reduce attack by predators by shocking predators

Question 33

How does bioluminescence work

Answer 33

Scintillons: spherical intracellular structures derived from invaginations of vacuole membranes that contain luceiferin (chlorophyll-derived molecule) Luciferase oxidizes luciferin, causing a flash of blue light Circadian rhythm in synthesis and destruction of scintillons: night phase (540 scintillons per cell) vs day phase (46/cell)

Question 34

Red tides

Answer 34

Surface upwellings of nutrients trigger blooms of photosynthetic dinoflagellates -some species in blooms produce neurotoxins-> paralytic shellfish poisoning

Question 35

Saxitoxins

Answer 35

Block Na+ movement through voltage-dependent channels in nerve and muscle cell membranes=prevent action potentials -dinoflagellates that produce toxins contain chloroplasts: ability to produce toxins drives from endosymbiotic Cyanobacteria

Question 36

Pfiesteria sp

Answer 36

Predatory dinoflagellate common in estuaries -kill fish by feeding on their skin (large lesions) -dinoflagellate zoospores feed on the fish by phagocytizing fish tissue through peduncle. - the peduncle is swollen with haustoria/like penetrating extensions when feeding on the fish