Lecture 13 Key Concepts/Terms

what are the types of protists?

alveolates
stramenopiles
rhizarians
excavates
amboebozoans
choanoflagellates

three key eukaryotic traits

multicellularity
sexual reproduction
compartmentalization (has organelles)

are protists monophyletic?

no, paraphyletic

the loss of the cell wall in eukaryotes led to what?

infoldings of the cell membrane that eventually led to the formation of the endoplasmic reticulum

what are the other steps of compartmentalization?

cytoskeleton (microtubules and microfilaments) increased complexity
ribosomes formed
regions of infolded cell membrane led to the early nucleus
lysosomes formed from the early ER
mitochondria formed from endosymbiosis
endosymbiosis with cyanobacteria led to the development of chloroplasts

how did the mitochondria form in eukaryotes

endosymbiosis

how did chloroplasts form in eukaryotic cells

endosymbiosis with cyanobacteria

Why is the loss of the cell wall critical to eukaryotic development?

it allowed the cell membrane to fold in on itself which eventually led to the evolution of all other organelles in eukaryotes

how are the protists paraphyletic?

tree indicates that genetic relationships among protist and the most recent common ancestor of protest are the same as eukaryotes
the term protist is a "catch all"

what are the variations in protist traits?

locomotion, cell surfaces, nutrition and reproduction

protist variable traits - locomotion

they can move via flagella, cilia or pseudopodia (false feet)

protist variable traits - cell surfaces

extracellular material varies widely
diatoms
cilia

protist variable traits - nutrition

some protists are heterotrophic and some are autotrophic
some are photosynthetic due to primary endosymbiosis and others due to secondary endosymbiosis

protist variable traits - reproduction

some are asexual and others sexual

how do protists show us the development of multicellularity

1.) eukaryotic cells begin living in close association
2.) associations become colonies
3.) individuals in colony take on different roles
4.) colony begins to function as an individual

types of alveolates

dinoflagellates, apicomplexans, ciliates

what are alveolates classified by?

the presence of alveoli in their cells

Dinoflagellates

causes red tide
photosynthetic
plate-like armor
two flagella
bioluminescent

Apicomplexa

parasites with apical complexes
causes malaria

ciliates

unicellular
typically large
heterotrophic
use cilia to move

types of stramenopiles

diatoms, brown algae, oomycetes

what are stramenopiles classified by?

fine hairs extending from their flagella

diatoms

photosynthetic
excrete protective silica shells
both sexual and asexual
only male gametes have flagella

brown algaes

photosynthetic via secondary endosymbiosis
multicellular
variable growth forms (filamentous or leaf-like)

oomycetes

use external digestion
cannot move
heterotrophic
molds and mildews

rhizarians

all unicellular and aquatic
thin, rigid pseudopodia

foraminiferans

amoeba like protist that has a shell and looks like a snail
fossilize easily due to the inorganic material in their shells

types of excavates

diplomonads, parabasalids, euglenids

Diplomads and Parabasalids

do not have mitochondria
cause diseases

euglenids

can be heterotrophic or photoautotrophic
arose via secondary symbiosis
reproduces via binary fission only

types of amoebozoans

loboseans, plasmodial slime molds, cellular slime molds

loboseans

move using pseudopodia
do not aggregate into colonies
what you think of when you think "amoeba"

plasmodial and cellular slime molds

can exist asexually as long as there is enough food
moving masses of slime
plasmodial - multinucleate
cellular - colonial cells
scientists think these led to multicellularity

Choanoflagellates

closest living relatives of animals

Opisthokonts

organisms from an ancestor with posterior flagellum (includes fungi, animals, and some protists)

Gymnopodium

dinoflagellate that causes red tide

Plasmodium falciparum

the apicomplexia that causes malaria

Paramecium

ciliate that lives in fresh water and eats other tiny organisms for food

giant kelp

a type of brown algae, the largest

white rust

common name usually used for diseases caused by oomycetes

Giardia intestinalis

a diplomonad parasite that causes diarrhea

Which of the following explains why protists are considered a paraphyletic group?

A) protists are prokaryotic
B) protists cannot be a monophyletic group because their morphology and behavior are so variable
C) protists lack a common ancestor
D) the MRCA of the protists also gave rise to plants, animals and fungi
E) B and D are correct

D) the MRCA of the protists also gave rise to plants, animals and fungi