phylum rhodophyta

Question 1

what red algae are known for

Answer 1

food –> nori (most popular species for food)
gel forming compounds —> carrageenan and agar (cultivated globally)
novel compounds —> evolved in response to microbial or herbivore attack
biodiversity in coastal systems —> more species than the other phyla
reef builders and give protection —> CCA

Question 2

general characteristics

Answer 2

mainly marine —> shallower to deep water environments
sister group to green algae
appear to be monophyletic
lots of diversity, many species
rhodophytes and chlorophytes possess plastids enclosed by 2 membranes —> result of endosymbiosis

Question 3

endosymbiosis evidence

Answer 3

plastid size —> roughly the same in eukaryotes and cyanobacteria
mode of reproduction —> binary fission, same as prokaryotes
chemically distinct membranes —> inner more like cyanobacteria, outer more like eukaryotes
have their own DNA —> single and circular, similar to prokaryotes
ribosomes —> similar to size of bacteria’s, own ability to synthesize proteins
molecular evidence

Question 4

when did red algae arise

Answer 4

precambrian (1.6 bya)
roughly same age as green algae but developed independently

Question 5

taxanomy

Answer 5

phylum rhodophyta
6,000-10,000 species
monophyletic group (from molecular data evidence)
7 classes; historically two (Florideophyceae and Bangiophyceae)

Question 6

bangiophyceae

Answer 6

Bangia and Porphyra
generally simple forms
1 cell thick, simple sheets, etc.

Question 7

Porphyra

Answer 7

nori
similar to ulva in greens
one cell thick, in a simple sheet

Question 8

Florideophyceae

Answer 8

most macroscopic marine red algae/most diverse
more complex thallus construction and reproduction

Question 9

characteristics of rhodophyta

Answer 9

granules of floridean starch occur in the cytoplasm instead of in chloroplasts due to photosynthesis
cell walls/coverings, plastids, cell division, reproduction

Question 10

cell wall structure

Answer 10

fibers of cellulose not as rigid as other phyla –> glucose polymer
gels of sugar polymers (ex: agar and carrageenan) or polysaccharides (flexible)
increases flexibility but may include CaCO3
easily grown through fragmentation
lack of coherent cell wall

Question 11

cell covering

Answer 11

extracellular matrix
less rigid than cell walls due to gels present, more “gooey”
loose network of cellulose microfibrils filled with gelatinous mixture
allows red algal cells to easily fuse with one another, exchange cytoplasmic and nuclear information
fosters wound repair
evolution of parasitic red algae —> do not have chloroplasts themselves but rely on nutrients from host
desiccation is slower due to having less rigid and more gelatinous structure
highly hydrophilic sulfated polygalactans (carrageenan and agar)

Question 12

carrageenan

Answer 12

highly sulfated compound in ECM
polysaccharide
17 types, many species
differ in gel strength
used in gel products to thicken and gel

Question 13

agar

Answer 13

less highly sulfated compound in ECM
gelatinous substance derived from polysaccharide that accumulated in cell walls
tends to be thicker than carrageenan
different in structure
used as an ingredient but also as a medium for microbiological work
gelling agent as unbranched polysaccharide obtained from cell walls of Gelidium and Gracilaria
thickener and stabilizer

Question 14

CaCO3 in cell wall structure

Answer 14

many species have this in their ECM
makes them pink
Corallinales order
different crystalline forms (polymorphs) of this depending on taxa
Calcite and Aragonite
coralline algae also produce high Mg calcite —-> susceptible to low pH
non-coralline algae produce aragonite
differ in solubility and susceptibility to changing chemistry ie. ocean acidification

Question 15

plastids

Answer 15

all have these, most have multiple
phycobilisomes
unstacked thylakoids with no grana
carotenoids and UV absorbing compounds
transfer energy via resonance to chlorophyll a reaction centers
differ in intensity of color due to large amounts of accessory pigment phycoerthrin which obscures chlorophyll a; absorbs blue and green

Question 16

phycobilisomes

Answer 16

on thylakoid membrane (no stacking) —> look like beads on a string
pigment-protein complexes with accessory pigments
phycoerythrin, phycocyanin, and allophycocyanin
phycobilin pigments
cyanobacteria also have these
harvesting light energy to transfer down to chlorophyll a

Question 17

photosynthetic pigments

Answer 17

have the most amount of pigments so they have the most diversity in color they reflect

Question 18

cell division

Answer 18

similar amongst different red algal groups
cytokinesis by furrowing
division of all cells if INCOMPLETE (aside from during reproduction)
formations of PIT CONNECTIONS AND PIT PLUGS (similar to plasmodesmata)

Question 19

pit connections

Answer 19

90% of cells do not completely divide
membrane lined pore
open region plugged with proteins
no cytoplasmic connections (unlike plasmodesmata)
may appear as threadlike linkages (beads on a string)
no true connection between the two cells remain
increase the strength of the thallus —> dense concentration of proteins there
primary and secondary pit connections
connect all cells together

Question 20

secondary pit connections

Answer 20

between non-sibling cells of the same body
adjacent cell, not from the one they produced
cytoplasmic connections can be re-established and eventually plugged with proteins
unequal cell division
way of allowing all cells to connect together even if they werent created by that cell
presumed to add strength to filaments and thallus

Question 21

reproduction

Answer 21

lack flagella at any life stage
loss of functional genes?
impacts on reproduction
decreases likelihood as sperm cannot swim to eggs

Question 22

asexual reproduction

Answer 22

unicellular mitotic spores
fragmentation and vegetative propagation
thallus structure fairly simple
other specialized propagules

Question 23

sexual reproduction

Answer 23

not documented in some early red algae
oogomous-nonflagellated egg and sperm as gametes in all others have —>
SPORIC ALTERNATION OF GENERATIONS - TRIPHASIC

Question 24

triphasic alternation of generations

Answer 24

gametophyte —> carposporophyte —> tetrasporophyte
evolutionary compensation for loss of flagella
producing more propagules to increase chances of reproduction/fertilization
biotic magnification

Question 25

biotic magnification

Answer 25

happens when using triphasic alternation of generations
probability of fertilization is low so when they do happen they undergo this
one fertilization event could end up producing 100s-1000s of spores

Question 26

tetraspore shapes

Answer 26

cruciate (4), tetrahedral, zonate (lines)
produced from tetrasporophyte

Question 27

carposporophyte

Answer 27

2n growth of diploid branch on female gametophyte
can produce 100s of spores

Question 28

tetrasporophyte

Answer 28

separate, free living entity

Question 29

bangiophyceae construction and growth

Answer 29

unicells, filaments or sheets
usually lack pit connections
no meristematic growth
DIFFUSE

Question 30

florideophyceae construction and growth

Answer 30

APICAL GROWTH
meristem
prominent apical cells or many apical cells
divide to produce the cells beneath them

Question 31

class bangiophyceae

Answer 31

primitive group
simple cells, all can potentially divide
intercalary meristem or diffuse growth
simple blades or sheets
rare sexual reproduction (except for Porphyra)
no tetrasporophyte
sporic alternation of generations
nori is one cell thick UNTIL reproduction, rudimentary reproduction triphasic AofG
biotic magnification

Question 32

porphyra reproduction

Answer 32

have a conchocelis phase that is more filamentous before meiosis
rudimentary triphasic AofG

spores —> mitosis —> gametophyte —> mitosis —> sperm and egg make zygote —> mitosis —> carpospores (2N) —> conchocelis phase (2N)

Question 33

drew baker

Answer 33

closed life history of nori —> allowed there to be a breakthrough for successful culture and new industry
single most domesticated seaweed, cultivated in many countries
rudimentary triphasic AofG
heteromorphic life cycle
found filamentous stage

Question 34

order bangiales

Answer 34

multicellular forms
cells appear identical internally
evolution of more complex forms
filamentous/parenchymatous genera
1-2 cells thick depending on genera

Porphyra yezoenis
more ruffled blades
Porphyra linearis (linear blades)

Question 35

Bangia vermicularis

Answer 35

extensive mats growing in high intertidal on rocks or boulders

Question 36

Porphyra perforata

Answer 36

tufts of blades growing attached to rocks in high intertidal
becoming less abundant due to climate change
can survive rich desiccation and completely recover

Question 37

Porphyrella californica

Answer 37

small red or pink blades often attacked to mussels or oysters