phylum chlorophyta Flashcards
green algae, lectures 4 and 5
monophyletic group
with land plants, green algae have this in common
ancestral green algae as ancestor to all terrestrial/true plants and chlorophyta
unifying features between green algae and plants
flagellated cells at some point in their life cycle
distinctive star shaped pattern where flagella insert into cell (actual structure varies by group)
mitochondria display flattened cristae
all have plastids, photosynthetic pigments, light harvesting pigments
flagellated cells
green algae and land plants have at some point in their lives
possess 2 or multiples of 2 flagella usually of equal length
structure, position, and type of cell division are used to classify classes for green algae
general characteristics of chlorophyta
vary in size from micro to macro
eukaryotes
occupy a variety of habitats (drifters, benthic, single-celled) - most environments
some species are biogeochemically important carbonate producers
some are important in modern and renewable fuels
bloom forming species under eutrophic or naturally high nutrient conditions
symbionts to invertebrates
economic wealth for food, drugs, supplements
when did first green algae arrive
Precambrian
1.6 billion years ago
younger than cyanobacteria
how many different green algae
diverse phylum with > 10,000 described species
~ 5,000 current species recognized
eukaryotic
eukaryotic photosynthetic cells
cell wall in addition to cell or plasma membrane
membrane bound light harvesting organelles —> chloroplasts
photoautotrophic
what green algae are
photosynthetic and get energy from the sun
process energy with membrane bound organelles —> chloroplasts and mitochondria
how organelles arose
from endosymbiotic events with a eukaryotic cell and a cyanobacterium
primary endosymbiosis evidence
size of plastids and bacteria
mode of reproduction (binary fission, must come from existing organelle)
have own DNA similar to bacteria (single and circular)
chemically distinct membranes (inner from outer, prokaryotic vs eukaryotic)
have own protein synthesizing machinery (ribosomes)
molecular evidence
multiple events to cause there to be a greater number of membranes wrapping organelles
green algal chloroplasts
2 membranes
thylakoid membranes stack within the grana surrounded by matrix (stroma - empty space)
produce and store starch in the stroma —> carbohydrate used for energy, product of photosynthesis
photosynthetic pigments embedded in thylakoid membrane
grana
stacks of thylakoids
stroma
empty space in chloroplast where starch is stored for energy
chlorophyll a
green algal light harvesting compound
reaction center pigment
accessory pigments for green algae
chlorophyll b (siphonoxanthin, siphonein)
carotenoids and UV absorbing molecules —> help with photoreception
can help with light harvesting but does not actually photosynthesize
want to capture light energy and transfer to chlorophyll a
from higher to lower energy
coloration of green algae
primarily absorb red and blue and reflect green to indicate color of thallus
type and amount of accessory pigments dictate absorption of other wavelengths
cells may have one or millions of chloroplasts
chloroplast shapes
can help dictate taxa
stellate “star shaped”
ribbon like
spiral
discoid
different morphologies in chlorophytes
unicells
colonies
filaments
sheets/blades/tubes
network of filaments/lattice
complex multicellular
coenocytic/siphonous (large one cell)
reproduction in algae
asexual —> mitotic zoospores, fission, fragmentation (multicellular), autocolony formation
sexual —> zygotic, gametic, sporic meiosis, alternation of generations, isomorphic and heteromorphic
haploid
one copy of chromosomes
diploid
2 copies of chromosomes
isomorphic
same morphology
heteromorphic
different morphology
isogamous
same sized gametes
anisogamous
different sized gametes
oogamous
production of eggs
gametes
always haploid
male and female
zygote
diploid always
from fertilization
alternation of generations
more than one adult phase
sporic meiosis
zygotic meiosis
meiosis occurs at the zygote after fertilization
individual —> gametes –fertilization—> zygote —-meiosis —-> cells —mitosis —> individuals
only common at very simple life stages
gametic meiosis
meiosis occurs going from individual to gametes
individual —meiosis —> gametes —fertilization—> zygote —mitosis—> individual
ex: Caulerpa
sporic meiosis
meiosis happens from sporophyte to spores
sporophyte—meiosis—>spores(1N) —-mitosis—>gametophytes(1N)—>gametes(1N)—>zygote(2N)–mitosis—>sporophyte(2N)
ex: Ulva
advantage of sporic meiosis
2 freeliving stages in one cycle
more copies can be made/increases stability in aquatic environment
heteromorphic generations
sporophyte and gametophytes look vastly different
reproduction
macroscopic/adult phases produce either gametes or spores
gametes usually male and female,
fertilization of haploid gametes ALWAYS results in diploid zygote
streptophyta
ancestral lineage that gave rise to all land/terrestrial plants
includes core chlorophytes