Ch. 27 Eukaryotes Flashcards
what are eukaryotes?
unicellular (fungi, protista)
multicellular (plants, animals)
what are prokaryotes?
can be unicellular or multicellular
-bacteria or archaea
what are heterotrophs?
eat food from other organisms/plants
cannot make own food
what are autotrophs?
can make own food from simple organic substances
define phagocytosis
engulf, package, transport and digest
food particles
-ex. amoebas do this
define pinocytosis
the ingestion of liquid into a cell by the budding of small vesicles from the cell membrane.
why is there so much more
diversity in size, shape, types of eukaryotes than prokaryotes?
- Membrane dynamics
- Compartmentalized metabolism
- Genome organization
- Genetic diversity by means of sex
- Life cycles
what is the life cycle of animal cells?
subset of haploid cells – meiosis – gametes – fertilization
1 multicellular phase: diploid
what is the life cycle of plant cells?
2 multicellular phases
1 haploid and 1 diploid
when does the cell cycle differ?
-Cell cycle differs when the organism reproduces sexually or asexually
- Sexually reproducing eukaryotes alternate states.
- Differences are most obvious in the proportion of time spent as haploid versus diploid
define endosymbiosis
symbiosis in which one of the symbiotic organisms lives inside the other
what evidence of endosymbiosis do we see in plant cells?
chloroplasts in plant cells most closely resemble certain photosynthetic bacteria (cyanobacteria)
- machinery of cyanobacteria closely resembles how thylakoid membranes organize machinery of chloroplasts
- processes of photosynthesis in both are almost identical
- chloroplasts have their own separate membranes
- chloroplast DNA is closely related to cyanobacteria rather than the DNA of their host
define symbiont
organisms that lives in closely evolved association with another species
define symbiosis
interaction between two different organisms living in close physical association, typically to the advantage of both.
what are 3 cases in which organisms use chloroplast endosymbiosis?
red algae
green algae
photosynthetic amoeba
what is a characteristic of chloroplast endosymbiotic DNA?
No longer need a big genome since they are not independent (free-living)
• Some genes migrated to the host nucleus
do we see endosymbiosis associated with mitochondria? if so, what are mitochondria most closely related to?
yes
proteobacteria
(except for a few extreme types in oxygen poor environments)
characteristic of eukaryotic cells that lack mitochondria
even eukaryotic cells that do not have mitochondria have traces of mitochondrial DNA in their genome
-many eukaryotic cells that do not have mitochondria have “hydrogenosomes” which generate ATP by anaerobic processes (allows them to function in oxygen poor environments)
hypotheses of the origins of eukaryotic cells/their DNA components
- Nuclear genes of eukaryotes are loaded with other organism genes.
- Probably multiple horizontal gene transfer events.
what are protists?
organisms having a nucleus but lacking other features specific to plants/animals/fungi
(usually microscopic eukaryotes and seaweeds)
what is algae?
photosynthetic protists
may be microscopic single celled organisms OR big visible clumps of seaweed
what is protozoa?
heterotrophic protists
(almost always single celled organisms)
-have remarkable diversity!!
what are the 7 major superkingdoms of eukaryotes?
- opisthokants
- amoebozoans
- archaeplastids
- stramenopiles
- alveolates
- rhizarians
- excavates
in which superkingdom do most eukaryotic species fall under?
opisthokanta
75% of species
(1.8 million species discovered so far)
which groups are in the opisthokant superkingdom?
- animals (complex multicellularity)
- choanoflagellates
- fungi (complex multicellularity)
what are choanoflagellates?
•type of opisthokant - 150 species • All unicellular protists • All have microvilli ring with a single flagellum • Closest genome to animals!
what are microsporidia?
- very closely related to fungi
- group of unicellular opisthokants
- parasites that live inside of animal cells
- only spores can live outside of host environments
- have no mitochondria/golgi apparatus/flagella
- cause illness and health problems in humans
what are some characteristics of the superkingdom amoebozoa?
-group of eukaryotes with amoeba like cells that move and gather food by means of pseudopodia
what are plasmodial slime molds?
type of amoebozoa
- coenecytic (multinucleotide cells, replicate nucleus but no cytokinesis)
- plasmodia generate sporangia (stalked structures that produce spores for dispersal in order to reproduce)
- often seen as lace like structures to the naked eye
“Weird creatures that form zygotes that repeatedly go
through mitosis but no cell division (coenocytic cells =
a single cell with many nuclei)…
this forms the plasmodia which builds the
sporangia, a reproductive body”
what are cellular slime molds?
type of amoebozoa
-live most of life as solitary amoeboid cells feeding on bacteria in soil. when starved, release cylic AMP signals to aggregate cells into a large chemical clump
“Soil amoeboid-style living. When starved of food
(bacteria), form aggregations called a slug. Slug can
form sporangia”
what are some characteristics of the superkingdom archaeplastida? what are the 3 groups of archaeplastids?
- photosynthetic organisms, superkingdom form which land plants arose
- descended from protists and acquired photosynthesis from endosymbiotic cyanobacterium
- glaucocystophytes
- red algae
- green algae
glaucocystophytes
-fresh water
-single-celled
-the highest number of features linking to the ancestral
cyanobacteria endosymbiont
-Peptidoglycan and biliprotein pigments that are
photosynthetic
red algae
- 5000 spp
- mostly marine
- walls of cellulose, chlorophyll a, and biliproteins
- Used in toothpaste, ice cream and agar.
green algae
-8,000 spp
-some are fresh water
-land plants originate here
-Green Algae Diversity: differences in form, chlorophyll
a and b, 2-membrane chloroplasts, phytoplankton,
worldwide
characteristics of the superkingdom stramenopila?
-Giant kelp, algae, and protozoans (photosynthetic)
-free-living and parasitic
-Odd flagellum with stiff hairs, some with second flagellum
that is not hairy
what are some types of stramenopila?
- Diatoms - most diverse stramenopiles (used in beer/responsible for 25% of worlds PSN)
- brown algae
characteristics of the superkingdom alveolata? what are the 3 types?
-Dinoflagellates (“whirling whip”): Most are SW spp. But a
few spp are common in FW, lots with chloroplasts, some
endosymbionts with coral especially (zooxanthellae).
Ex. Red Tides
-Ciliates: cilia, lots of parasitic spp, not generally
parasitic to humans (ex. paramecium)
-Apicomplexans (parasites, only gametes locomote):
Ex. Plasmodium falciparum (MALARIA)
655,000 human deaths in 2011 alone
what is the fossil record of protists?
1.8 billion years
• Oldest Eukaryote is in Australian rocks
• 1200 million year old multicellular red algae in Canada
• 750 million year old rock in Arizona has diverse
amoebazoans
