Topic 12: Rhodophyta (Red Algae) Flashcards
What is the role of encrusting coralline red algae in coral reef
ecosystems?
They help to cement the reef structure and maintain net reef accretion
A crustlike coralline red algae has been found deeper than
any other photosynthetic eukaryote (at 268 m deep in the
Bahamas). Explain how this alga can grow at depths where
there is only ~0.0005% of surface light intensity
They contain large amounts of phycoerythrin which allows them to absorb the blue light that penetrates deeper than other wavelengths
- Indicate two commercial uses of red algae.
Pharmaceutical: compounds that inhibti herbivory or microbial activity
Human food: Pyropia (nori), caragenens or agars
- Describe the extracellular matrix (ECM) in red algae.
It is flexible are far less rigid than other cell walls of plants and algae
Cellulose microfibrils (minor component)
Amorphous gel-like mixture (largest component)
Sulphated polymers of galactose (agar and carrageenan) and mucilage
Some may also deposit CaCO3
Do red algal cell have intercellular connections that allow
exchange of solutes and gases between cells, such as
plasmodesmata?
No they do not have these kind of connections
They form brief secondary pit plug connections to exchange genetic information, but these become plugged
- What are pit plugs? How many kinds are there?
These are proteinaceous connections between cells after cell division, that help to structure the algae
They do not provide intercellular connection
Primary Pit Pug: structural link, sister cells
Secondary Pit Plug: exchange info non-sister cells (temporary)
Describe 5 unique features of the cell biology of red algae
(excluding the triphasic life cycle).
They lack centrioles
Lack flagella from vegatative cells, spores and gametes
Pit Plugs
Cell-cell fusion of cells other than gametes (communication between different cell types)
Cell elongation and repair
Development of multinucleate cells and polyploid nuceli
Using a clearly labeled diagram, describe the triphasic life
history of a Florideophycean red alga.
- What is the evolutionary advantage of the triphasic life cycle?
In triphasic, the zygote develops into a carposporophyte which has the capacity to produce many tetrasporophytes and thus produce many gametes
In short it allows for the amplification of a single fertilization event
Which one of the following multicellular stages are free-living:
gametophyte, carposporophyte or tetrasporophyte?
The gametophyte is free living and the sporophyte is free living
But the carposporophyte is not free living, because it exists on the female gametophyte
Draw the biphasic life cycle of Bangiophyceans.
