Chapter 28: Protists (Part 1)
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Eukaryotes are thought to go back ___ billion years. BUT what?
2.7 Billion years. BUT no fossils to support this.
_____ as old as 1.5 billion years do show evidence of larger cells with internal membranes and thicker walls.
Microfossils as old as 1.5 billion years do show evidence of larger cells with ____ and ____.
- Internal membranes
- Thicker walls
The _____ and _____ may have evolved from infoldings of membranes.
Nucleus & Endoplasmic Reticulum
Mitochondria probably evolved from (anaerobic/aerobic) bacteria that were engulfed by a larger cell.
Living together, within
Chloroplasts/plastids probably evolved from ______ bacteria that were engulfed. This is referred to as _____ endosymbiosis.
photosynthetic bacteria; secondary
True or False: Endosymbiosis is supported by evidence.
- Several organells contain their own DNA which closely resembles that of prokaryotes.
- Mitosis evolved in eukaryotes
- The process is thought to have come about over time as the mechanisms of mitosis vary among organisms
What evidence supports endosymbiosis?
- 1. Several organeles contain their own DNA- closely resembles that of prokaryotes
- 2. Mitosis evolved in eukaryotes. The process is thought to have evolved over time as the mechanisms of mitosis vary among organisms.
True or false: "Kingdom" Protista is paraphyletic, meaning it is the largest kingdom.
FALSE. Kingdom Protista is paraphyletic and NOT a kingdom at all.
What does Paraphyletic mean?
descended from a common evolutionary ancestor or ancestral group, but not including all the descendant groups.
Some ______ different and distantly related single-celled organisms are simply lumped together for lack of knowledge of evolutionary relationships that could sort them out.
200,000 single-celled organisms
The authors of your textbook have grouped the protists into_______ all shown diverging simultaneously from a common ancestor.
In what ways do protist cell surfaces vary?
- Plasma membrane only (amoebas)
- Plasma membrane plus ECM (extracellular matrix)
Give an example of a protist with a plasma membrane PLUS an ECM
Diatoms and foraminifera secrete glassy shells of silica
List the various means of protist locomotion:
- flagella or cilia
- pseudopodia (axopodia, filopodia)
- other means of propulsion
Other terms that mean pseudopodia are:
axopodia and filopodia
Protists have a range of nutritional strategies. Namely:
use light to feed
Obtain nutrition from other sources
Both phototrophic and hetertrophic
Heterotrophs include two subgroups:
- Osmotrophs-ingest food in soluble form (already dissolved)
- Phagotrophs-bring visible (solid) food particles into food vacuoles.
- Type of heterotroph
- ingests already dissolved, soluble food
- type of heterotroph
- bring solid food particles inside via food vacuoles
True or false: Protists only produce asexually
FALSE. Protists reproduce both sexually and asexually
List 3 ways a protist reproduces asexually:
Define sexual protist reproduction:
Meiosis: allows for genetic recombination
True or false: Colonial protists may be the bridge to multi-cellularity.
True! This is important.
Name two types of flagellated protists lacking mitochondria.
Classified under Supergroup Excavata.
What are the 5 Protists Supergroups?
- I. Excavata
- II. Chromalveolata
- III. Rhizaria
- IV. Archaeplastida
- V. Unikonta
- Based on morphology of cytoskeletonSome members have an "excavated" feeding groove on one side
Note: Support for this supergroup is rather weak)
Which supergroup is controversial?
What are the defining characteristics of Diplomonads?
- TWO nucli
- move with multiple flagella
- Modified mitochondria called mitosomes
What is a mitosome and where is it found?
Modified mitochondria found in diplomonads
Giardia Intestinalis fits into what supergroup, and what does it do?
- Causes diarrhea.
- Found in contaminated water and can pass from human to human.
What are the defining characteristics of Parabasalids?
- Undulating membranesMove with flagella
- reduced mitochondria called Hydrogenosomes
What is a Hydrogenosome?
Reduced mitochondria found in parabasalids--supergroup excavata
- Type of parabasalid
- lives in the gut of termite and digests cellulose.
- STD found in humans
The root Trich means:
- Referring to flagella in Trichonympha species--parabasalids--supergroup excavata
What are the four groups of Excavata?
- Supergroup Excavata
- Members of Euglenozoa
- Free-living eukaryotes
- Pocket at one end with one or two flagella
- Have mitochondria
- Flexible pellicle can change shape
- one-third of euglenoids have chloroplasts and are fully atrophic: may become heterotrophic in the dark
- others lack chloroplasts and are heterotrophic
- Reproduction by mitosis
- no sexual reproduction known
_____ and _____ are the two major groups of Euglenozoa
Euglenoids and Kinetoplastids
Euglenoids reproduce by:
Mitosis; No sexual reproduction known
Euglenoids are free living _____.
True or False: Euglenoids have mitochondria.
Kinoplastid refers to:
unique single mitochondrion in each cell
What technique do kinetoplastids use to evade immune response?
- Surface proteins are changed frequently
Trypanosomes are disease causing _____?
Name 3 common diseases caused by Trypanosomes:
- African sleeping sickness
- Chagas disease
African sleeping sickness:
- Transmitted by tsetse fly
- Caused by Trypanosome (disease-causing kinetoplastids)
- Transmitted by Sand Flies.
- Caused by Trypanosome (disease causing kinetoplastid)
- Caused by Typanosoma cruzi
- Small wild mammals and beetles carry the parasite
- May have originated by secondary endosymbiosis
- Very large, diverse clade
- Two Subgroups: Alveolata and Stramenopila
True or False: Supergroup Chromaleolata contains protists that may have originated by secondary endosymbiosis.
The two subgroups of Supergroup Chromalveolata are:
Protists with submembrane vesicles (like alveoli)
Subgroup Alveolata includes three groups:
- 1. Dinoflagellates
- 2. Apicomplexans
- 3. Ciliates
Alveolata Group A: Dinoflagellates
- Photosynthetic unicells
- Have two flagella located in grooves in cellulose plates
- both marine and freshwater
- some are luminous
- "red tides" result from blooms of dinoflagellates
- produce powerful toxin that inhibits the diaphragm causing respiratory failure in vertebrates
- reproduce mainly asexually
Are dinoflagellates found in marine or freshwater enviorments?
True or false: Some dinoflagellates are luminous
"Red Tides" result from "blooms" of ?
"Red tides" are harmful to which industry?
Why would an abundance of toxic dinoflagellates result in the death or marine mammals, fish, and birds?
Dinoflagellates produce powerful toxins that inhibit the diaphragm, causing respiratory failure in vertebrates.
Dinoflagellates reproduce primarily by (asexual/sexual) reproduction.
Alveolata Group B: Apicomplexans:
- COMPLEX APEX
- spore-forming parasites of mammals
- have apical complex of organells, vacuoles, fibrils, microtubules at one end of cell.
_____ are the spore-forming parasites of mammals.
Give an example of an apicomplexan
Plasmodium- causes malaria
What does Plasmodium cause?
What is the vector for Plasmodium?
The Anopheles mosquito
Explain the life cycle of Plasmodium
Sporozites, morizoites, etc
Why don't people with sickle cells get Malaria?
People with sickle cells don't have cells that last long enough for Malaria to fully develop.
Alveolata Group C: Ciliates
- Have large number of cilia arranged in longitudinal rows or spirals
- some cilia may be fused into sheets, spikes, or rods that function as mouths, paddles, teeth, or feet--Paramecium
- Have a pellicle
- UNICELLULAR HETEROTROPHS
- micronucleus- may only be needed for sexual reproduction
- macronucleus- divides by mitosis and is involved with physiological function
- vacuoles for ingesting food and maintaining water balance
- conjugation involves exchange of micronuclei
Ciliates are (unicellular/multicellular) (autotrophs/heterotrophs).
Ciliates have both a ____ and ____ nucleus.
- Micro-sexual reproduction
- Macro-mitosis, involved with physiological function
Protists with Fine hairs
Subgroup of Chromalveolates
Stramenopila are a subgroup of ____ that includes the following species:
- Golden Algae
- Brown Algae
- Oomycetes (water molds)
Stramenopila Species A: Gold Algae
- freshwater OR marine (plankton)
- ALL are photosynthetic; some mixotrophs
- Most are unicellular, some colonial
- Many species can form protective cysts if environment conditions deteriorate. (kinda like spores)
How many flagella do Golden Algae have?
Are golden algae found in marine or freshwater environments?
True or False: All Golden Algae are mixotrophs.
False. All Golden Algae are photosynthetic. Some are mixotrophs.
Many species from this chromalveolata stramenophile group can form protective cysts if environment conditions deteriorate.
Stramenopila Species B: Brown Algae
- Most conspicious seaweed in northern regions (kelps)
- thallus = blade, stipe, holdfast
- algin= gel-forming substance used to thicken puddings, salad dressings
- undergoes alternation of generations: sporophyte or gamatophyte
Which of the following species from the Chromalveolates-Stramenophila group accounts for most of the seaweeds in northern regions?
A. Golden Algae
D. Brown Algae
D. brown algae
(this multiple choice question has been scrambled)
Blade, stipe, holdfast
What is Algin and where does it come from?
- Algin is a gel-forming substance used to thicken puddings, salad dressings, etc.
- Algin is made from Brown Algae
Is Kelp a plant?
- No! Kelp might look like a plant, but it lacks the complex tissues such as xylem that are characteristics of plants.
- Kelp is a type of Brown Algae
goes through meiosis to produce spores
smaller than sporophytes, filamentous individuals
Stramenopiles Species C: Diatoms
- double shells (look like a box with a lid)
- made of opaline silica
- vibrating fibrils line grooves (raphes)
- diatomaceous earth -- filtering medium
Are diatoms unicellular or multicellular?
Which stramenopile species is made of opaline silica?
Vibrating fibrils line grooves found on Diatoms
Stramenopiles Species D: Oomycetes (water molds)
- all are parasites or saprobes
- used to be categorized as fungi
- have motile spores (zoospores) with unequal flagella
- zoospores produce asexually
- sexual reproduction via male and female gametes
- most oomycetes live in water, but terrestrial forms are plant pathogens
Which stramenophile species has motile spores with unequal flagella?
A. Gold Algae
B. Brown Algae
(this multiple choice question has been scrambled)
- Type of terrestrial oomycete
- causes late blight of potatoes (Irish potato famine)
- type of oomycete
- fish pathogen
- can infect amphibians and kill amphibian eggs
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