Rhodophyta Flashcards

1
Q

Majority of seaweeds are what type of algae

A

Red- more diverse than all other seaweed groups combined

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2
Q

Where is red/ brown algae dominate

Where is green algae dominant

A

Tropical and temperate

Polar and sun polar

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3
Q

__________ algae are one of the oldest groups of eukaryotic algae

A

Red

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4
Q

Chloroplasts of red algae appear to have originated from ________ by ______ endosymbiosis

A

Cyanobacteria

Primary

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5
Q

The major feature of a red algal cell are a chloroplast with _________ per band and only _____ chloroplast membranes

A

One thylakoid
2

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6
Q

What phylum have Floridean starch grains in cytoplasm

A

Red algae

Rhodophyta

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7
Q

Floridian starch grains

A

Long term storage product

Similar to amylopectin of higher plants, is highly branched and resembles Cyanobacteria starch

(No amylose like green algae)

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8
Q

Starch grains cluster around ________ of chloroplast in primitive red algae

A

Pyrenoid body

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9
Q

Thylakoid structures in Rhodophyta

A

Unstacked (simile to Cyanobacteria)

Phycobilisomes occur on the surface of the thylakoids

Chlorophyll a found in the chloroplasts and carotenoids: zeaxanthin

Accessory pigments: phycoerythrin: absorption in green and reflect red

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10
Q

Chromatic variation

A

Colour of red algae varies depending on where it grows
-orange/red light (long wavelength)->phycocyanins
-green light (short wavelength)->phycoerythrin

Species may be yellow-green when growing in the intertidal zone or deep purple when growing 10-20m below the surface (Subtidal zone)

Ratio of phycoerythrin to chlorophyll is much greater at low light intensisties

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11
Q

Sulfated polysaccharides

A

Typical for many red algae
-major constituents of agar (less sulfated) and carrageenans (more sulfated)-> extracted for commercial uses

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12
Q

Agar

A

Mainly obtained commercially from species Gelidium, pterocladia
-collected by diving, dragging and raking at low tide
-agar extracted under pressure in autoclave, decolonized and deodorized with activated charcoal, filtered-> food and drug

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13
Q

Calcification of Rhodophyta

A

-Coralline red algae=heavily calcified walls
-helps establish fossil record
-crystalline calcite (forms of CaCO3)
-possible that CaCO3 formation helps hard best nutrients

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14
Q

Red algae were probably the first __________

Why?

A

Multicellular organisms

-conspired of cellulosic microfibril network+amorphous matrix of sulphated polysaccharide polymers and mucigel

-sulfated polysaccharide polymers create a multicellular organism by hankering every cell in a gel mass
-mucigels expand with hydration and help cell dispersal and attachment

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15
Q

Diffuse

A

Cell division is not localized

Early in multicellular red algae

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16
Q

In most red algae, there is a meristematic region and growth via division of an _______

A

Apical region

Cell divisions of apical cells increase number of cells in filaments

17
Q

Septum and pit plugs in red algae

A

In most red algae, septum (cross wall) formation is incomplete leaving a membrane lined pore.

Put plugs used to fill opening in the cell wall

Form during cell division between sister cells (primary put plugs) and in some red algae, between adjacent cells (secondary pit plugs)

Variation in pit structure used to determine phylogenetic relationships

Hypothesized to increase stability of the thallus (no function in translocation) - currents moving them around so need strength

18
Q

Formation of pit plugs steps

A
  1. Cross wall begins to form following cell division
  2. Cell wall development stops before completely closing the opening between two cells
    3.parallel vesicles line up in the gap to form a “plug” (granular protein mass)
    4.Plug stabilized on either side by a flattened “plug cap” (carbohydrate dome)
19
Q

Formation of secondary out plug

A
  1. Unequal cell division produces a smaller conjunctor cell
    2.Fusion of cytoplasmic between smaller and adjacent, non-sister cell
  2. Nuclear transfer between cells (cell rendered binucleate)

Secondary pit plug connections help exchange genetic information between adjacent cells and strength the entire thallus

20
Q

Red algae sexual reproduction

A

Asexually by discharging unicellular, non motile spermatia into the water

21
Q

Sexual reproduction in red algae involved what?

A

-3 generations (triphasic): gametophyte, carposporophyte and tetrasporophyte

22
Q

Porphyra sp. attaches itself to rocks how?

A

Multicellular rhizoidal attachment (holdfast)

23
Q

Porphyra sp. thallus appearance

A

Begin life as uniseriate filaments but this stage is replaced by parenchymatous sheets of cells (1 to 2 cells thick)

24
Q

Porphyra sp. economic use

A

Nori

25
Q

Porphyra asexual and sexual reproduction

A

Asexual: neutral spores

Sexual: blade stage (macro thallus= gametophyte); branched-filamentous stage (conchocelis stage=sporophyte)

26
Q

Cultivation of Porphyra sp.

A

Spores collected and seeded on shells

After collecting of conchospores, these are now ready to be seeded and grown on cultivation nets in the field.