Topic 8 - Orgin of Eukarya/Protists Flashcards
What are ecological relationships?
- pairs of species can be grouped on their ecological interactions
what is mutualism (+ +)?
- both species A and B benefit from the other’s presence.
-both species benefit
example: coral and algae
what is competition ( - - )?
- both species A and B suffer from each other’s presence.
- both species feed on similar prey, they are negatively impacted by the presence of the other because they will have less food
- example: cheetah and lions
what is predation (- +)?
- when species A easts species B
example:
wolves hunting moose
owls hunting mouse
what is parasitism (- +)?
- species A steals nutrition or other resources from species B
- one in which one organism, the parasite, lives off of another organism, the host, harming it and possibly causing death.
- example: humans and mosquitoes.
what is commensalism (0 +)?
- Speices A lives on or with Species B, but neither harms nor benefits species B.
- example
bird making a nest in a tree
whales and barnacles.
what is amensalism (- 0)?
- Species A harms species B. Species B does nothing for species A
-only one organism is hurt.
- example:
cattle trample on grass
penicillin kills bacteria
what does + mean?
- beneficial
what does - mean?
- negative
what does 0 mean?
- neutral
what is a symbiotic relationship?
- when members of two species live in close, often obligatory, contact with each other.
what does syn mean?
together
what does bio mean?
life
what relationships does symbiosis involve?
- mutualism, commensalism or parasitism.
what is called the host?
- if one species is much larger than the other.
what is a species called that is smaller than the other?
- symbiont
what is a endosymbiotant?
- if the prokaryote is inside the host organism
what does endo mean?
- within
when did eukaryotes arise?
- The first eukaryotic cell arose more than a billion years after prokaryotes appeared.
- The oldest fossil eukaryote is 1.8 billion years
Eukaryotic vs Prokaryotic
- eukaryotes have DNA in linear chromosomes in membrane-bound nuclei.
- eukaryotes have other membrane-bound organelles such as
mitochondria and plastids (e.g. chloroplasts) - eukaryotes are often much larger than prokyotes.
- eukaryotes have a cytoskeleton that allows them to change change shape, for example being able to engulf particles
what is the orgin?
- originally hypothesized that
eukaryotic cells arose
gradually from a prokaryotic
ancestor
a. ancestral pre-eukaryotic cell very likely to have been a
member of the Archaea
how did the ancestral host cell develop some structures?
- gradually by
infoldings of cell membrane
– endoplasmic reticulum
– nuclear envelope - endosymbiosis also played an important role.
what did the ancestral nucleated host cell take on?
- endosymbiotic aerobic
heterotrophic prokaryote, which was probably a proteobacterium* that
used oxygen and organic matter to
make energy - this eventually led to the formation of mitochondria.
what did members of other lineages engulf?
- photosynthetic prokaryotes.
- they were most likely cyanobacteria that used
light and CO2 to make organic
compounds - then they became photosynthetic protists and plants.
a. the endosymbionts became plastids
(e.g., chloroplasts)
what is serial endosymbiosis?
- first mitochondria
and then plastids were
endosymbiotically acquired by the
ancestors of photosynthetic
eukaryotes
What’s the evidence for endosymbiosis in
evolution of eukaryotes?
- mitochondria and chloroplasts have their
own DNA, which they replicate independently
of nuclear DNA - this DNA is circular, as is prokaryotic DNA
- plastids (e.g., chloroplasts) have 2 or more
cell membrane layers- 2 membranes if engulfed a free cyanobacteria
*2 or more if engulfed other eukaryote.
- 2 membranes if engulfed a free cyanobacteria
what is primary endosymbiosis?
- refers to a free-living
prokaryote being taken on by a eukaryotic cell - The eukaryote is englfed a prokaryote, which led to the creation of mitochondria.
what is secondary endosymbiosis?
- refers to the taking on of a
photosynthetic (plastid-containing) eukaryotic cell by
a heterotrophic eukaryotic cell - the resulted organelles will be very complex and will be surrounded by serval additional cell memebranes.
- occurs when a eukaryotic cell engulfs a cell that has already undergone primary endosymbiosis.
what is the difference between primary and secondary endosymbiosis?
- Primary endosymbiosis occurs when a eukaryotic cell engulfs and absorbs a prokaryotic cell, such as a smaller cell that undergoes photosynthesis (eg. cyanobacteria).
- Secondary endosymbiosis occurs when a eukaryotic cell engulfs and absorbs another eukaryotic cell. it produces green and brown algae.
what is horizontal gene transfer
through endosymbiosis?
- occurs through genome fusion between different species when two symbiotic organisms become endosymbiotic.
- This occurs when one species is taken inside the cytoplasm of another species, which ultimately results in a genome consisting of genes from both the endosymbiont and the host.
what is metabolic diversification?
- it sets the stage for a second wave of diversity.
-the different metabolic strategies that organisms have evolved to obtain energy.
what is the second wave catalyzed by?
- structural diversity of eukaryotic cells.
what is structural diversity?
- the range of different physical landscapes within a habitat; the more diversity, the more opportunities for different organisms to thrive.
what was the third wave of diversification?
- the origin of multicellular bodies in several eukaryotic cells evolved new ways of reproduction.
what are multicellular bodies?
- composed of more than one cell, with groups of cells differentiating to take on specialized functions.
what is Mitosis?
- in mitosis,
one diploid
cell divides
once to form
two diploid
(2n) cells - so there is an original cell with 2n=4
- then chromosomes replicate.
then one diploid cell divides into two diploid cells. (2x (2n=4)
What is meiosis?
- in meiosis,
one diploid
cell divides
twice to form
four haploid
(1n) cells
(reduction
division) - so there is an original cell with 2n=4
- then chromosomes replicate.
then one diploid cell divides into two diploid cells. (2x (2n=4) - then the two diploid cells divide again to form 4 gamete cells which are halpoid (1n)
what is syngamy?
occurs when two haploid (1n) gametes fuse
what does syn mean
together
what does gam mean?
gamete
what does syngamy form?
- forms diploid (2n) zygote (fertilized egg)
– zygo = twinned/joined
In multicellular eukaryotes, which cellular division doe sit use to form a multicellular embryo?
- uses mitotic cell divison
What does the further growth of the embryo lead to?
- it leads to morphological different level stages.
**only some taxa have larvae
what does larvae lead to?
- it leads to a reproductively mature adult
when does sexual reproduction occur?
- occurs when two parents
produce offspring with novel combinations of genes
from both parents
what are examples that ARE NOT sex?
- binary fission and duplication via mitosis
what does sex require?
- meiosis* (meiosis* and subsequent fusion of
haploid nuclei from different parents) and subsequent fusion of
haploid nuclei from different parents
what is the most common for a non-monophyletic group?
- protists
- they are mostly unicellular eukaryotes that are not
plants, fungi or animals - animals, fungi and plants area each closely related to a different
protist group - the old
Kingdom Protista
was paraphyletic (as there are many different clades of protists)
Can protsist species bephotoautotrophic,
heterotrophic and
mixotrophic?
yes
what is a mixotrophic?
- are both photoautotrophic and
heterotrophic
what do single-celled protists have to exist as?
- have to exist as
complete organisms unto
themselves
– internal cellular structure much
more complex than for cells from
multicellular organisms
what are selected groups?
groups of protists?
Do some protists lack mitochindria?
yes
what are diplomonads?
- originally thought to be
ancient eukaryotic lineages that evolved before the acquisition of
endosymbiotic bacteria that evolved into mitochondria
Are there still mitochindairal genes present in diplomonads?
- yes
- in some species in these groups, very
tiny nonfunctional mitochondrial remnants
(mitosomes) are present in the cell - suggests that these protists ancestrally had
regular mitochondria but lost them during
subsequent evolution– these taxa are all found in anaerobic (oxygenfree) habitats, including guts of animals
– mitochondria are aerobic, and hence they
would not function in these habitats
Define the structure of a diplomonad?
- they have multiple flagella and two seperate nuclei.
-diplo= double, two folded.
- has obvious mitosomes (double-membrane bound organelles found in some unicellular eukaryotes,)
what is the genus of diplomonad?
- Giardia which infects the human intestine and causes dramatic diarrhea
Can non-human mammals be infected by Giardia?
yes,
- it causes beaver fever
is a parasitic infection of the digestive system. Symptoms include severe abdominal discomfort and diarrhea, but some people have no symptoms
what are apicomplexans?
- they are parasites of animals
what is the structure of Apicomplexans?
- complex of organelles for
penetrating host tissues at apex of cell - organelles have 4 membranes and
cyanobacterial DNA; this is strong
evidence of secondary
endosymbiosis
How many host species do apicomplexans require?
- require 2 or more
host species to complete their life cycles
what is plasmodium?
- parasites that
causes malaria, need both
mosquitoes and vertebrates as hosts
(humans are hosts for four
Plasmodium spp.) - Plasmodium spends part of its life
in blood-feeding flies and part in
vertebrates
what are ciliates?
-they have many cilia which names them ciliates
what does a cilia do?
- used for locomotion and for capturing food
- many used cilia as their legs to be active and move
what do many free-living species feed on bacteria
and smaller protists by?
phagocytosis (cellular eating)
phag = eat and cyto=cell
how to ciliates reproduce?
- reproduce asexually by
binary fission, but sometimes engage in a
form of sexual reproduction called
conjugation
what is conjugation?
- transfer of plasmids from one ciliate to another
what is a paramecium?
- swims in fresh water by beating its thousands of cilia, and feeds on smaller microorganisms such as bacteria and algae
what is an amoebas?
- it is a common name for referring to linages of protists that move by extending blunt lobes called pseudopodia.
what is a pseudopodia?
- temporary projections of the cytoplasm of the cell.
- they help in feeding the amoeba.
what process do amoebas use to eat food?
- they use phagocytosis to eat food and engulf particles.
what does pseudo mean?
- false
what dos pod mean?
foot
what does cyto mean?
cell
what is an Amorbozoans?
- it is a clade of amoebas, and maybe is related to fungi and Animalia
what are the three different groups of Amoebozoans?
- solitary amoebas
- plasmodial slime molds
- cellular slime molds.
what is a solitary amoeba?
- are amorphous single-celled protists with lobe-shaped pseudopodia
- mainly predators of bacteria and smaller
protists
what is a plasmodial slime molds?
- start out with a single
nucleus but then undergo repeated mitosis without cell
division - they become a single giant supercell with free-flowing cytoplasm and nuclei that hunts bacteria on the forest floor.
what is cellular slime molds?
- they start as a single-cell body
- when food is limited the adjacent cells get together but maintain separate cell membranes.
- the slug will migrate to. high spot and many cells form a stalk.
- many cells climb up the stalk and develop a
hard coat that allows them to withstand drying - they disperse in the wind and somewhere wet on land.
what are cellular slime molds studied by?
- by those interested in how cooperation
and self-sacrifice can evolve
what is algae?
- photoautotrophic eukaryotes that are not
members of the Kingdom Plantae - they are NOT monophyletic
- many are single celled and others are multicellular and large.
what is brown algae?
- it is multicellular and large
what is green algae?
- has bright green pigments visible in chloroplasts.
- chloro= green
- more than 7000 species live in freshwater.
- other stay in damp soil, snow or within other eukaryotes.
- they range in size from single-celled to multicellular. which can be qualified as a. seaweed
what are the two groups that green algae is divided in?
- chlorophytes
- Charophytes (multicellular and morphologically complex)
a. thought to sister taxa to plants
what are sedimentary rocks?
- formed from ‘skeletons’ of
marine protists
how much is carbon fixation and oxygen production apart of photosyntheisis in algae?
-30% of annual photosynthesis is done by algae
what do prostsits cause?
- diseases of plants, wildlife, livestock and
humans (malaria) - accidental consumption of protists in food can
cause sickness (shellfish poisoning)
-some macroalgae deliberately eaten by humans, like seaweed in sushi.
