Topic 8: Dinoflagellates Flashcards
*Describe the ecological importance of dinoflagellates.
Form large blooms that can be toxic – shellfish poisoning
Eaten by protozoa, rotifers and fish
Symbiosis with coral
*Based on cell covering characteristics, what is the difference between a thecate (or armoured) and athecate (or unarmoured) dinoflagellate?
Thecate: Vesicles contain a thecal plate (Cellulose), these form the theca and its internal
Athecate: the vesicles are empty
*What are thecal plates made of?
The thecal plates are formed of cellulose
*What are the morphological differences between a desmokont and a dikont cell
Desmokont: made of 2 large plates/valves
2 dissimilar flagella emerge at cell apex
Dikont: Divided into 2 parts
Apical: epitheca
Posterior: hypotheca
Separated by the cingulum
Sulcus extends posteriorly from cingulum
2 dissimilar flagella emerge from pore between sulcus and cingulum
This is the majority of species
- Describe the pusule and its function.
Branched membranes or vesiles dervied from invagination of cell membrane
Opens to the surface in the vicinity of the flagella
Highly developed in non-photosyntheitc forms
Function: Excretion, osmoregulation, maybe an uptake process
- Describe motility in dinokont dinoflagellates.
They are excellent swimmers
Transverse flagellum: 50% of swimming speed and rotation
Ribbon Shaped
Posterior Flagellum: 50% of swimming speed and steering
- Define the following terms: trichocyst,, peridinin, sulcus, cingulum, amphiesmal, zooxanthellae,,.
Peridinin: This is a unique acessory xanthophyll
Sulcus: This is the groove where the posterior flagella lies
Cingulum: This is the groove where the transverse flagellum lies
Tricocyst: Vesicle with ejectile protein rods at periphery for defense
Amphiesmal: These are vesicles under the membrane, also known as alveoli confer cell shape
Zooxanthellae: These are the dinoflagellates that form symbiosis with coral polyps
EVERYTHING PAST THIS IS FOR AFTER MIDTERM
POST MIDTERM * How is bioluminescence produced in dinoflagellates?
Produced in scintillons
Contain luciferin, luciferase and luciferin-binding protein (LBP)
pH decrease: luciferin release from LBP
Luciferinase oxidizes luciferin with O2
Flash of blue light (0.1 sec)
POST MIDTERM* Draw the life cycle of a typical dinoflagellate.
POST MIDTERM* Briefly explain the role of cyst formation in the survival and dispersal of dinoflagellates
Due to abiotic changes in environment that are less favourable for dinoflagellates
Produce cysts that can sit dormant and be moved by water currents and begin to grow when the conditions become good again
POST MIDTERM*Why do dinoflagellates outcompete other phytoplankton in well-stratified waters at the end of the growing season in marine temperate zones?
They have wide range of nutrient capabilities
Very efficient flagella motion to get to optimal light and nutrient levels
Storage of lots of phosphorus
POST MIDTERMDefine planozygote and hypnozygote
Planozygote: These are zygotes that are flagellated
Hypnozygote: These are zygotes that aren’t flagellated
POST MIDTERMDefine scintillon
These are intracellular bodies located at cell periphery that contain the necessary components for bioluminescence
