lecture 8 (dinoflagellates)

Question 1

what is the ecological importance of dinoflagellates?

Answer 1

They form very dense blooms, some of the largest phytoplankton

Question 2

what is the characteristic movement type of dinoflagellates?

Answer 2

rotary swimming using 2 flagella

Question 3

what organism is responsible for red tides

Answer 3

dinoflagellates

Question 4

how are dinoflagellates fossilized?

Answer 4

they form a resistant dormant cyst which can accumulate in sediments

Question 5

based on cell covering characteristics, what is the difference between thecate and athecate dinoflagellates?

Answer 5

thecate = armoured, contain internal thecal plates made of cellulose
athecate = unarmoured, thecal vesicles are empty

Question 6

what is a thecal plate made of

Answer 6

cellulose

Question 7

what are the two halves of an unarmoured dinoflagellate called?

Answer 7

epicone (top), hypocone (bottom)

Question 8

what is an amphiesmal?

Answer 8

the vesicle under the cell membrane of dinoflagellates (also called thecal vesicles)

Question 9

what are the morphological differences between a desmokont and dinokont cell?

Answer 9

desmokont = 2 large cell plates (valves) and two dissimilar flagella at cell apex
dinokont = typical dinoflagellates, divided into two halves (apical and posterior), separated by a cingulum

Question 10

how fast does a dinoflagellate swim

Answer 10

200-500 um/s

Question 11

what is the pustule? what is its function?

Answer 11

an branched sac/tubules that opens into the vicinity of flagella.
function = excretion, osmoregulation and maybe uptake

Question 12

what pigments do dinoflagellates have?

Answer 12

chl a, chl c, b-carotene, and a unique xanthophyll (peridinin)

Question 13

storage of dinoflagellates

Answer 13

starch grains

Question 14

describe motility in dinokont dinoflagellates

Answer 14

transverse flagellum in the cingulum that provides 50% of swimming speed and rotation
longitudinal flagellum that lies in the sulcus, provides 50% of forward swimming speed and steering

Question 15

define trichocysts and their function

Answer 15

present in almost all dinoflagellates. A vesicle with ejectile protein rods at the cell periphery.
function: defense, escape from predators

Question 16

define scintillon and function

Answer 16

allow for bioluminescence under pH decrease, located intracellularly, at the cell periphery.
function = protection against predation, startles predator, makes predators more visible

Question 17

define peridinin

Answer 17

a unique accessory xanthophyll in dinoflagellates

Question 18

define sulcus

Answer 18

the groove that holds the longitudinal flagella

Question 19

define zooxanthellae

Answer 19

dinoflagellates who form a symbiotic relationship with coral polyps

Question 20

define planozygote

Answer 20

a flagellated zygote of dinoflagellates

Question 21

define hyponozygote

Answer 21

non-flagellated zygote of dinoflagellates

Question 22

equation for bioluminescence

Answer 22

luciferin + O2 ->(using luciferase enzyme to oxydize)-> oxyluciferin + light

Question 23

describe the life cycle of dinoflagellates

Answer 23

asexual and sexual reproduction
vegetative (haploid) dino can undergo asexual reproduction/form temporary cysts, or undergo sexual reproduction and release haploid gametes. gametes fertilize and become a 2N planozygote with 2 longitudinal flagella. then this can undergo meiosis and become a N adult or not and be a 2N hypnozygote (cyst like, no flagella) . This hyponozygote can undergo meiosis to be an N adult, or not and become a 2N planozygote again before undergoing meiosis and becoming a vegetative N adult.

Question 24

what is the role of cyst formation in survival/dispersal of dinoflagellates?

Answer 24

often due to nutrient, irradiance, photoperiod, or temperature changes. may also follow asexual/sexual reproduction.
can help to survive bad conditions, also can be transported in ship ballast water

Question 25

do dinoflagellates undergo diel vertical migration?

Answer 25

yes

Question 26

why do dinoflagellates outcompete most other phytoplankton in well-stratified waters at the end of the growing season?

Answer 26

wide nutritional capabilities, but has efficient flagella motion (can do positive phototaxis to move towards light/nutrients), can store a large amount of phosphorus

Question 27

what are some struggles dinoflagellates face in terms of getting nutrients

Answer 27

low SA:V ratio (low rate of nutrient uptake)
vulnerable to turbulence (will encyst and fall to the bottom)

Question 28

what is the cyst phase of dinoflagellates called

Answer 28

hypnzygote