Bikonta Flashcards
eukarya
different cell morphology than bacteria and archaea
- larger
- membrane-bound organelles
- more extensive cytoskeleton
nuclear envelope
linear chromosomes
multiple independent lineages with multicellularity
different reproduction
- asexually via mitosis and cell division
- sexual reproduction via meiosis
nuclear envelope
hypothesized to have arisen by infoldings of the plasma membrane
occurs in some bacteria
also created the ER
modern Eukarya have continuous nuclear envelopes and ER
advantage: operates
transcription & translation
Endosymbiosis theory
theory that mitochondria and chloroplasts originated when a bacteria cell was taken in by another cell
most Eukaryote organisms have mitochondria
Lynn Margulis
created the endosymbiosis theory
endosymbiosis
association between two species with one living inside the cells of the other
hypothesis for the origin of membrane-bound organelles
evidence that original mitochondria were 𝛼-proteobacterium
- size
- replicate by fission
- double membranes
- mitochondria genomes- gene sequences related to Bacteria rather than Eukarya nuclear genome
secondary endosymbiosis
photosynthetic protist engulfed by another protist
-results in a chloroplast organelle with 4 membranes
evidence that original chloroplasts were from a protist that engulfed a cyanobacterium
similarities between chloroplasts and cyanobacteria:
- size
- circular DNA genome with similar genes
- some protists have chloroplasts with peptidoglycan outer layer
multicellularity
one of the most significant changes to life on Earth
arose independently multiple times
hypothesized to have started with cells sticking together after cell division
“colonies” of cells could have higher fitness due to specialization
-different cells express different genes
protist
term used for Eukarya that are not land plants, fungi or animals
another bad term because it does not reflect evolutionary history
not a monophyletic group
-multiple, independent origins
Bikonta
“two poles,” cells with two flagella (if present)
some protists and plants
Unikonta
“one pole,” cells with one flagellum (if present)
some protists, fungi, & animals
Bikonta ecological importance
abundant (like bacteria and archaea)
key role in aquatic food webs
-plankton
potential role for buffering climate change
Plankton
general term for organisms that drift in open oceans
many species of plankton are phototsythetic protists (e.g. primary producers)
potential role of bikonta for buffering climate change
Bikonta store carbon
increased abundance of protist phytoplankton could take CO2 out of atmosphere
Carbon trapped in marine food webs, dead organisms sink to bottom of ocean
Carbon sink: long term reservoir of carbon
Excavata
unicellular
most have flagellum
many found only in the digestive tract of animals, including species that aid digestion of cellulose in insects
bodies typically supported by internal rod consisting of microtubules or strips of proteins under plasma membrane
excavated feeding groove
many lack recognizable mitochondria
- but nuclear DNA contains genes typical in mitochondria
- cells contain vestigial mitochondria organelles
Rhizaria
single-celled
lack cell walls
vary widely in form but most are amoeba-like
move by amoeboid motion with long slender pseudopodia
includes foraminiferans
Foraminiferans
best studied Rhizaria
foramin = “hole”
produce calcium carbonate shells with holes through which the pseudopodia
abundant marine plankton, found at deep benthic zones
Alveolata
type of Rhizaria
unicellular
includes ciliates and dinoflagellates
alveoli
flattened, membrane-bound vesicles packed into continuous layer supporting the cell plasma membrane
-provides support for the cell
Ciliates
type of Alveolata
unicellular
covered in cilia
-used to swim
2 district nuclei
-micronucleus and macronucleus
SAR group
stramenopila
alveolata
rhizaria
dinoflagellates
type of Alveolata
unicellular
more species marine than freshwater
some species capable of bioluminescence
- indirect inducible defense
- draw attention to the predator in hopes that another predator eat their predator and they are saved
a few species are responsible for harmful agal blooms
-the red bloom pictured in slides
stramenopila
at some point in life cycle, all have flagella that are covered with distinctive hollow “hair”
unicellular and multicellular forms
includes diatoms, water molds, and brown algae
diatoms
major component of plankton
-free-floating microorganism of marine and freshwater environments
most important primary producers in freshwater and marine ecosystems
- are extremely abundant
- 20-25% of carbon fixation
- major source of oxygen and food
fide variety of shapes with glassy cell walls
water molds
important decomposers in freshwater ecosystems, but some are terrestrial
-saprophytic: feed on dead and decaying matter
brown algae
multicellular
includes many seaweeds and kelp
red algae
mostly multicellular
primary marine
lack flagellum
some species contribute to reef building
most have chloroplasts that contain pigment phycoerythrin
absorbs blue and green wavelengths; reflects red wavelengths
able to thrive in deep water because blue/green light penetrates water better than other wavelengths
green algae
important producers in freshwater and nearshore ocean
cell walls contain cellulose
chloroplasts contain chlorophyll a + b
-different varieties of light-capturing pigments
includes lichens
shared traits between green algae and land plants
cell walls contain cellulose
chloroplasts contain chlorophyll a + b
-different varieties of light-capturing pigments
lichens
are stable associations between fungi and either green algae (most) or cyanobacteria
ecosystem service
benefits that humans derive, directly or indirectly, from ecosystem functions
plant ecosystem services
oxygen production
-photosynthesis
primary productivity
-key to carbon cycle; base of food webs
erosion control
-root systems of plants hold soil in place
flood control
-plants retain water, provide buffer
climate control
-shade reduces temperature, raised humidity (wind protection)
fuel
-wood burning, fossil fuels, ethanol, biodiesel
fibers
-cloth, rope, lumber, paper, etc
medicines
-over 100 active ingredients in medicines are derived from plants
land plants
angiosperms (flowering plants)
byrophyta (mosses)
gymnosperms
pteridophyta
anthocerophyta (hornworts)
equisetophyta (horsetails)
plants transition to land
more resources for photosynthesis: light and carbon dioxide
challenge: water loss
- cuticle and stomata
challenge: UV light
accumulation of flavonoids
challenge: gravity
- transport of water and upright growth in less dense air
cuticle
watertight sealant that prevents water loss
stoma (plural stomata)
press that can open and close and control gas exchange
controlled by guard cells
flavonoids
UV absorbing compounds that prevent DNA damage
vascular tissue
elongated cells organized into water conducting tissue
elaboration of vascular tissue with two types of cells: tracheids and vessel elements
tracheids
long, thin, tapering cells
increased structural support and ability for water to move through easily
secondary cell walls supported by complex polymer lignin
primary cell wall is made of cellulose
found in all vascular plants
lignin
complex polymer built from six-carbon rings
gives complexity (pteridophyta, gymnosperms, angiosperms)
vessel elements
wider, with gaps for more efficient water movement (angiosperms)
found in gnetophytes and angiosperms
Bryophyta
most common in moist forests
gametophyte-dominated alternation of generation
-typical fossils of early land plants
homospory
water needed to move gametes
sporophytes
multicellular and diploid
produce spores by meiosis
gametophytes
multicellular and haploid
produce gametes by mitosis
Pteridophyta (ferns)
- sporophyte
- homospory
- water needed to move gametes
most common with epiphytic habit
large leaves (fronds) are coiled when young (fiddleheads)
sporophyte-dominated alteration of generations
homospory- one type of spores
spores produced in sori
epiphytic habit
in trees on branches and such
fronds
large leafs of ferns
fiddleheads
coiled fronds when the fern is young
sori
clusters on undersides of leaves that produce spores
ferns
gymnosperms
- sporophyte
- heterospory
- water is NOT needed to move gametes; mainly wind
“naked seed”
-ovules not enclosed
includes coffers, Ginkgo, and Cycads
two types of spores (heterospory)
-pollen and ovules
fertilization produces seed
dominant plants 300 - 145 mya
seed
embryo that is surrounded by a supply of nutrients
angiosperms
- sporophytes
- heterospory
- water is NOT needed to move gametes; mainly pollinators
high diversity = 350,000 extant species
dominant plants for pat 145 million years
angiosperm = encased seed
flower reproductive organ
some species produce nutritious and brightly colored fruit that is derived from ovary
flowers
reproductive organ
stamen: male
carpel: female
anther: produce pollen
directed pollination hypothesis- flowers are adaptations that attract specific pollinators
- increasing likelihood of pollination
- decreasing likelihood of cross-pollination
scents, shapes, colors, and nectar
coevolution between plants and pollinations
higher diversification rates
fruit
derived from the ovary, tissue surrounding seeds
tissue often nutritious and brightly colored
aids seed dispersal
-animals are attracted to fruit eats it and moves in to another area
fruit-animals study
study tested hypothesis fruit colors have evolved to increase detection by seed-dispersing animals
it analyzed fruit colors against background at two sites:
- uganda: seed dispersers are diurnal, color vision primates
- more bright and eye-popping
- madagascar: seed dispersers are nocturnal,, color blind lemurs
- more conspicuous
malaria
caused by protists
one of the world’s most infectious diseases
paraphyletic group
represent some, but not all of the descendants of a single common ancestor
detritus
dead organic matter
bioluminescence
emit light via an enzyme-catalyzed reaction
sporangia
spore-producing structures
gametangia
specialized reproductive organs for gametes
antheridium
sperm-producing gametangia
archegonium
egg-producing gametangia
alternation of generations
individuals either exist in a multicellular haploid phase or a multicellular diploid phase
embryophyta
retention of the embryo in some land plants
analogous to pregnancy in mammals
microsporangia
spore-producing structures that produce microspores
microspores
develop into male gametophytes, which produce the small gametes called sperm by mitosis
megasporangia
spore-producing structures that produce megaspores
megaspores
develop into female gametophytes, which produce the large gametes called eggs
pollen grain
when in heterosporous seed plants, the microspore germinates to form a tiny male gametophyte that is surrounded by a tough coat or sporopollenin
nectar
sugar-rich fluid that is food for pollinators
monocots
one of the two major groups of angiosperms
i.e. grasses (corn, wheat), orchids, palms, lilies..
dicots
one of the two major groups of angiosperms
i.e. beans, roses, buttercups, daisies, oaks, and maples
cotyledon
“seed-leaf”
stores nutrients and supplies them to the developing embryonic plant
eudicots
“true dicots”
a monophyletic line that includes most of the plants once considered dicots
stamen
male
carpel
female
anther
produce pollen
