Eukaryotic Cells Chapter 27 Flashcards
eukaryotes can change shape because of
flexibility in cytoskeleton
dynamic cytoskeleton allows for
endocytosis
in eukaryotic cells, energy metabolism is localized in
mitochondria/chloroplasts
eukaryotes are limited in how they get carbon and energy because
mito-aerobic respiration and photosynthesis
why is it a big deal that eukaryotes can engulf larger foodstuffs?
it increases their complexity between organisms
where does eukaryotic diversity come from?
being able to replicate multiple strands of DNA that not only code for proteins but also gene expression
why did unicellular eukaryotes do so well?
b/c they could remodel cell shape, regulate genes well, all which led to evolving complex life cycle & diff cell types
__ promotes genetic diversity in eukaryotes & gives rise to distinctive life cycle
sex
asexual organisms use __ to reproduce, but some organisms ____ until conditions improve
mitosis; fuse into diploid (zygote)
diatoms
exist as diploid
reproduce asexually
get smaller & then meiosis triggered to produce haploid gametes
most diverse stramenopiles
silica skeletons
account for 1/2 of photosynthesis in the sea
chloroplasts originated as
cyanobacteria
-was a form of endosymbiosis
chloroplasts have small genomes because
many transported to nucleus-nucleus could supply the chloroplasts’ requirements
mitochondria originated as
endosymbiotic bacteria: proteobacteria
mitochondria have small genome because
it migrated to the nucleus
hydrogenosomes and mitosomes originated as
mitochondria but deal with anaerobic environments
what are the 2 hypotheses for how the eukaryotic cell originated?
- eukaryote resembles archaea b/c host for mito-producing endosymbiosis
- euk cell entirely started as symbiotic association between proteobacterium & archaeon
protists
have nucleus but lack all else animals, plants & fungi have
algae
photosynthetic protists
protozoa
heterotrophic protists
which is the most diverse eukaryotic superkingdom?
ours, opisthokonts
opisthokonts
animals, fungi and some protists
- flagellum movement
- heterotrophic
- animals most sophisticated
which is most related to animals?
choanoflagellates
microsporadia
single-celled opisthokonts that infect host
-closely related to fungi
amoebas move by
pseudopodia
most amoebas stay
in the soil to attack other microorganisms
-others attack people
plasmodial slime molds
haploid cells fuse to form zygotes that keep doing mitosis but NOT cell division (coenocytic)
coenocytic
have many nuclei within one giant cell
starvation causes cellular slime molds to
aggregate into a slug–>sporangia–>disperse
archaeplastids include ____
how old are they?
land plants
1200 my
archaeplastids are the ___ most diverse
second after opisthokonts
which organism contains the most ancestral cyanobacterial endosymbiont features than any other algae?
glaucocystophytes
red algae
walls made of cellulose
their primary pigments are chlorophyll & biliproteins
green algae
big features: chlorophyll a & b in chloroplasts that have 2 membranes and a unique attachment for flagella
what are the two branches of green algae?
chlorophytes
-streptophytes
streptophytes
more important for humans b/c diversified in fresh water and then made it to land
unicells–>cell clusters–>filaments on intermediate branches–>complex multicellular algae
which 3 superkingdoms dominate eukaryotic diversity in the oceans?
stramenopiles, alveolates and rhizarians
stramenopiles
unicellular kelps, algae, protozoa free-living cells/parasites 2 flagellae -most photosynthetic: brown algae & diatoms
alveolata
photosynthetic and heterotrophic species
have small vesicles (cortical alveoli) store calcium ions
-also include protists called ciliates
photosynthetic alveolates belong to
dinoflagellates
red tide
when nutrients are supplied to coastal waters in large amounts (toxic)
apicomplexans
group of alveolates that cause malaria
how did photosynthesis spread through eukaryotes?
repeated endosymbioses involving eukaryotic algae
eukaryotes appropriated ___ from cyanobacteria and spread it via ___
oxygenic photosynthesis; horizontal transfer
how long have eukaryotes been around?
1800 mya
why did more diversity come about in 800-700 mya?
more diversity because b/c protists evolved eating other protists as well as oxygen content of seawater increasing
what happened around 252-266 mya?
most significant changes occurred among photosynthesizers
-new ones came about: dinoflagellates and cocclithophorid algae and diatoms
list all 7 superkingdoms
opisthokonts amoebozoans archaeplastids stramenopiles alveolates rhizarians excavates
