28 Flashcards
protists
mostly unicellular groups of eukaryotes
all Eukaryotes that are not animals, plants, or fungi
mixotroph
combine photosynthesis and heterotrophic nutrition
Endosymbiosis
a relationship between two species in which one organism lives inside the cell or cells of another organism (host)
Secondary endosymbiosis
red algae and green algae underwent this. They were ingested in the food vacuoles of heterotrophic eukaryotes and became endosymbionts themselves
holdfast
anchors the algae
stipe
stem like; supports the leaf like blades
pseudopodia
extensions that may bulge from almost anywhere on the cell surface.
how protists move and feed
Features of Eukaryotes
Presence of a nucleus (complete with nuclear envelope)
•Mitochondria, ER, other internal structures (including well-developed cytoskeleton)
• Multicellularity
•Sexual reproduction
• Several complex RNA polymerases
-Translation begins with methionine
4 supergroups of eukaryotes
- The ‘SAR’ Clade
- Excavata
- Archaeplastida
- Unikonta
supergroup
a classification category for a clade that’s “above” the
level of kingdom but below the level of domain.
clade
a group of biological taxa (as species) that includes all descendants of one common ancestor.
Morphological innovation
gave early eukaryotes a new way to manage and process genetic information
Cilates
have a diploid micronucleus that is involved only in reproduction and a polyploid macronucleus where transcription occurs (i.e. Paramecium)
Diplomonads
have 2 nuclei that appear identical
Forams, red algae, slime molds
certain cells contain many nuclei
Dinoflagellates
have chromosomes that lack histones and attach to the nuclear envelope
Supergroup EXCAVATA
• Excavates
• characterized by their
cytoskeletons
• some have an “excavated” feeding groove
Euglenids
have a pocket at one of the cell from which one or to flagella emerge
Stramenopila includes several groups of heterotrophs and some of the most important phototrophs on the planet:
– Diatoms
– Golden Algae
– Brown Algae
Diatoms
are unicellular algae that have a unique glass-like wall made of hydrated silica embedded in an organic matrix
Briefly describe the hypotheses for the origin of the nuclear envelope.
The cellular membrane folded in on itself and separated from the outer cell membrane to envelop the chromosomes-the nucleus. Also creating the endoplasmic reticulum.
Evidence- Infoldings are present in some bacteria
Nuclear envelopes is continuous with ER
Advantage- Separation of transcription and translation- allowing specific genes to be expressed instead of the entire genome
What is the role of endosymbiosis in eukaryote evolution?
A process in eukaruotic evolution in which a heterotrophic eukaryotic cell engulfed a photosynthetic euk. cell, which survived in a symbiotic relationship inside the heterotrophic cell.
Plastids that are surrounded by more than two membranes are evidence of
secondary endosymbiosis.
Biologists think that endosymbiosis gave rise to mitochondria before plastids partly because
all eukaryotes have mitochondria (or their remnants), whereas many eukaryotes do not have plastids.
In life cycles with an alternation of generations, multicellular haploid forms alternate with
multicellular diploid forms.
Based on the phylogenetic tree in Figure 28.2, which of the following statements is correct?
The most basal (first to diverge) eukaryotic supergroup cannot be determined.
Which protists are in the same eukaryotic supergroup as land plants?
green algae and red algae
what supergroup are diplomonads in?
Excavata
Who are members of Excavata?
Euglenozoans, Parabasalids, Diplmonads
what does the SAR clade stand for?
– Stramenopiles
– Alveolates
– Rhizaria
who are members of the Stramenopiles clade?
diatoms, golden and brown algae
who are members of the Alveolates clade?
dinoflagellates, ciliates
who are members of the rhizaria clade?
forams, radiolarians
who are members of the archaeaplastida?
– Green algae, red algae
– Kingdom Plantae
who are members of unikonta?
– Opisthokonta: Choanoflagellates, nucleariids
– Amoebozoans: slime molds, amoebas
– Kingdoms Fungi and Animalia
what are the closest relative of land plants?
green algae
is conjugation a form of reproduction?
no it is a swapping of genetic information
what are the only supergroups that have only protists?
SAR clade and Excavata
what are reasons that prove endosymbiosis occurred?
o Chloroplasts and mitochondria both contain their own DNA
o Have an inner and outer membrane (the outer membrane is from the host cell)
o The host cell cant create a plastid or mitochondria, it can only absorb them
what are characteristics of Excavata?
characterized by their
cytoskeletons
• have an “excavated” feeding groove
Organisms with modified mitochondria:
diplomonads and parabasalids
what are characteristics of diplomonads?
have reduced mitochondria called mitosomes
Have two equal-sized nuclei and multiple flagella (looks like eyes)
the SAR clade is a _____ supergroup
monophyletic
what is a characteristic of clade Stramenopila?
Most have a “hairy” flagellum paired with a “smooth” flagellum
what are unicellular algae that have a unique glass-like wall made of hydrated silica embedded in an organic matrix?
diatoms
where do golden algae get their color from?
carotenoids
what is the brown algae photosynthetic pigment?
fucoxanthin
what are characteristics of Alveolates?
have membrane- enclosed sacs (alveoli) just under the plasma membrane
what are characteristics of Dinoflagellates?
have two flagella and each cell is reinforced by cellulose plates
they are bioluminescent
what causes toxic red tides?
dinoflagellate blooms
what are characteristics of Ciliates?
They have large macronuclei and small micronuclei
– The micronuclei function during conjugation
amoebas feed and move by ____
pseudopodia
amoebas are a _____ group
paraphyletic
what supergroup includes red algae, green algae, AND land plants?
archaeaplestida
what is the pigment that gives red algae its color?
phycoerythrin
what are the largest seaweeds and most abundant?
red algae
what group goes through conjugation?
Ciliates
Euglenids and Kinetoplastids are part of what supergroup?
Excavata
giardia is part of what supergroup? and what specifically?
Excavata
it is a diplomonad
