Bio 170 Notes Ch. 28: Protists
Pagel Protists are members of the eukaryotic domain. They are among the most diverse and smallest within the domain.
They first were discovered by Antoni van Leewenhoek when ne analyzed organisms in a drop of pona water.
Protists can be as small as prokaryotes (.5-2 mm)
Protists once belonged to the Protista kingdom until scientists determined that some protists were more closely related to animais, fungi, a
plants than to other protists. Most eukaryotes are single celled organisms. they have organelles such as mitochondria, Golgi apparatuse la nucleus.
We also discuss several other topics like What is produced through chemical reactions?
some protists can gain energy as lautotrophs, but others are heterotrophs & some are mixotrophs. If you want to learn more check out What is the process of organizing and interpreting sensory input?
Protists can reproduce asexually, sexually, or go through meiosis q fertilization.
There are five super groups the Excavata, the chromalveolata, the Archaeplastida the pritaria, & the Unikonta.
Euglenozoans Diplomonads lack plasids & have modified mitochondria the modified mitochondria aise called mitosomes they lack electron transport & get energy from anaerobic biochemical If you want to learn more check out What is a riser?
Pathways. They have two equal sized nucleis multiple flagella! Many diplomonads are parasites such as Giardia lambly
Page 2 Parabasalids have reduced mitochondria called hydrogenosomes which release hydrogen as a by-product. The most known example of this is Trichomonas vaginalis Eugleno zoans, include parasites, prestitory heterotropns, & photo synthetic autotrophs. kineto plastias are englenozoans, that have one large Don't forget about the age old question of What makes these people particular relative to others?
mitochondrian with a large mass of DNA called a kinetoplast. This protist can feed on prokaryotes &
animals/plants fungi that can parasitized by protists. Best example is Trypanosoma, which causes sleeping sickness. Trypanosomes work by altering the protein Don't forget about the age old question of Define the octet rule.
that coats the cell when ever the immune system tries to attack it. Euglenids only have one to two flagella that come out of
a pocket. Many euglenids are mixotrophs & eat by phagocytosis. An exampleis Euglena which is commonly found in pond water.
Brown loomycetes Algae
Iciliates lapicomplexans, Dino flagel Algae stramenopiles
Alveolates. some data suggests that chromalveolates are a monophyler group a believed be descendent of red algae and originate from the second endosymbiosis. Most controversial of the five supergroups Don't forget about the age old question of What makes current flow in circuit?
Alveolates have a well supported monophyly dueto its molecular semantics. Species in this group have alveoli (membrane-bounded sacs) that lie under the surface of the plasma membrane. It is hypothesized
that they may help stabilize the cell surface or regulate
Page 3 cell's water to non concentration Dino flagellates are cells that are reinforced by cellulose plates. Two flagellates located in grooves cause dino flagellates spin as they move. They are common
freshwater and marine plankton and live near the Surface of water. The photosynthetic dinoflagellates.
can be mixotrophs a half of dinoflagellates are heterotrophs. Dinoflagellates can cause the "redtide which can contain toxin producing species such as karenia brevis.
Apicomplex ans are mainly parasites and can cause serious illness. The parasites spread as tiny infectious cells called isporozoites These cells contain a special complex of organell es for penetrating cells & tissues in the host. They are heterotrophis, but have a modified
plastid possibly of red algae origin. Well known example: Plasmodium -> malarichi
Life cycle of Plasmodium
0 An Anopheles sporozoites enter 2 After 48-72 hrs the mais quito bits a liver cells & become merozoites break abar person injecting merozoites& infect blood cells causing Plasmodium.
rea blood cells
Othoman The gametes 5 Another Anopheles 6 Some merozoites
'Tuman are formed from a mosquito bites a t formgametocytes
gameto cutes. Derson & then - acona arier fertilizatiak nosquito becomes infected. - becomes into
@ In the mosquito rent 3 An oocyst forms, digestive tract - meiosis thoocyst releases → back to step t
sporozoites which & zygote forms
move to the salivarygland.
Page 4 Giliates use cilia to moves feed. They can cover the entire cell surface or be clustered. They have two nuclei : micronuclei & macronuclei (conjugation occurs. when haploid micronuclei are exchanged between two
organisms Ciliates reproduce through binary fission.
Example: Paramecium caudatum Stramenopiles are the other sub group include important photosynthetic organisms & several heterotrophs. Diatoms are unicellular algae that have a glass-like wall made up of silicon dioxide. The walls overlap one another, much like a shoe box and its lid would Diatoms can experience and withstand pressure as high as 1.4x106 kg/m? It is estimated that there are 100,000 living species, making it a highly diverse group. They
play a major part in the phytoplankton we see in lakes and oceans. Because diatoms are photo sunthetic some scientists wish to promote blooms in an effort
to curb growing carbon dioxide levels. Example: Triceratiom morlandin
Yellow and brown carotenoid are what give golden algae its color. It is typically biflagellate, and all of them are are photosynthetic but some can be mixotrophic can occasionally perform phagocytosis. Example: Dinobryon Brown Algae are the most complex and largest algae. They are multicellular, live in marine areasy (typically temperate coasts), and are colored by brown/olive carotenoids. What we consider seaweed! Thallus refers algae that is
plant like. BUT thalli do not have roots; but rather a hold fast (rootlike), stipe (stemlike), blades ( leaf like) Example: | Kelp & Laminaria Alternation of Generations: the alternation of multicellular
hapioid & diploid forms. Occurs in plants too Life cycle of brown algae: Laminaria:
2 Sporophytes are found in water just below the line of low tide
2 cells on surface of blade develop into sporangia
Pages 3 sporangia do meiosis & create zoospores
1 The eggs become
fertilized. .. .
Males release sperm < 1 half develop into male I are attracted to the & another half develop chemicals secreted by egas into female gametophytes
9 zygotes grow to become sporophytes Sremain with female gametophyte.
Comycetes are water molds, white rusts, & downy mildews. Originally classified fungi, Oomycetes (most) have muitingcleate filaments Chypae) which are similar to fungi, cell walls have cellulose while fungi have a polysaccharide chitin. The similar appearance is due to convergent evolution. Example: Rhx to platberen Watestans + cause of the Irish Famine.
Rhizaria is one of the newer super groups, determined by molecular systematics. Evidence suggests that rhizarians are a monophyletic group. Many species grouped in Rhizaria. are called amoebas. Amoebas are defined as species that more and eat through pseudopodid, extensions that bludge from anywhere on the cell surface. Example: radiolarian, Radiolarians have symmetrical internal skeletons made up of silica. The pseudopodia are reinforced by bundles of microtubules which are covered in cytoplasm.
The deat radiolarians have created a thick layer of ooze on the sea floor.
Page 6 The foraminiferans or forams are named for their porous cells. The tests are made up of a single piece of organic material covered with hardened calcium carbonate. They get nourishment from the Photosynthesis of a symbiotic algae. They are found in marine & freshwater environments, they are single celled organisms and the largest can grow up to a diameter of several centimeters. Most of the forams discovered are fossilized.
The first of the molecular phylogenies to be identified the cercozoans contain most of the amoeboids flagellated protists. They can be found in marine, freshwater, a sori environments. They gain energy as neterotrophs, with a
few of them being mixotrophs, and even fewer autotrophs. Example: Paulinella Chromatophora.
Charophytes Red Algae Land plant Chlorophytes
Green Algae 475 million years ago (at the very least) land plants emerged from the Green Algae lineage, and with the
Green Algae & Red Algae make up the Archaeplastida supergroup. | Red Algae is pigmented by the accessory pigment phycoerythrin
Those living shallower waters have less phyloerythrin. The species that don't have any pigmentation are heterotrophs
and live as parasites on pigmented algae. Most red algae are multicellular & have alternation of generations without flagellated stages. Example: Porphyra aka nori
Green Algae is divided into two subsets the charophytes &
Page 7 the chlorophytes. The group is closely linked to land plants and some scientists believe that reen algae and land plants should be grouped together. Charophytes are the more closely linked group to land plants.
Chlorophytes mainly live in fresh water environments but can be found in marine and terrestrial onesas well. Some live symbiotically with other eukaryotes. Some of
the chlorophytes can even surive in snow.
The evolution of large sized complexity came by:
1. Formation of colonies 2. Formation of true mu Hicellular bodies 3. Repeated division of nuclei with no cytoplasmic
division, Example of chlorophytes viva, aka Sea Lettuce.
[ChoanoflagelmesFungi Inocleariias Amoebozoans. unikorta is the most recently developed super group that is extremely diverse. There are two clades in the supergroups Amoebozocor & opisthokonts Support for the relation between the two clades can be found in the comparison of myosin protein & studies on several genes. Scientists do not know where the root for the unikonta starts. The amoebozoans includes several species of amoebas induding slime molds, gumnamoebas, & entamoebas Slime molds. (mycerozoans) have a similar system of sporingto that found in fungi, but it is believe to have occurred through covergent evolution. One of the subgroups of Slime mold is Diasmodial slime mold which creates a plasmodium
Page 8 which can grow up to several centimeters. This is not a multicellular organism. The mold is a heterotroph,
gaining nutrients through phagocytosis. Cellular slime molds reproduce asexually and are single celled organism that can band together in harsh sircumstances. They can create Cheaters which never become part of the main stalk.
Gymnamoebas are amoebaloans that are heterotrophs and eat bacteria and other protists.
Entamoeba are parasites which infect all vertebrates and some invertebrates. Homans host at least o of these
organisms with only one of them being known to be pathogenic. Opisthokonts include animals, fungi, & several other protists. Nocleariids and fungi are the reason scientists abandoned the Protista kingdom.
symbiotic protists greatly affect the world, ranging from coral reefs, termits and anuper mastigote TO Plasmodium and nomans. Many of the protists are Photosynthetic and contribute to the depletion of carbon dioxide, and many are eaten Wym other organisms.