Chapter 28 - Protists Flashcards
1
Q
How far back in time do eukaryotes go?
A
2.7 billion years (educated guess)
- some microfossils are believed to be 1.5 billion years old
- nucleus and ER may have evolved from infoldings of membranes
2
Q
Endosymbiotic Theory
A
“Condition of living together within”
- a relationship between 2 species in which one organism lives inside the cell or cells of another organism (the host)
3
Q
Endosymbiosis Theory
- Evidence & Examples
A
- Mitochondria may have evolved from aerobic bacteria by a larger cell - endosymbiosis
- Chloroplasts/plastids may have evolved from photosynthetic bacteria that were engulfed - endosymbiosis/secondary endosymbiosis
- several organelles contain their own DNA
4
Q
“Kingdom Protista is paraphyletic and not a kingdom at all…”
A
- run along side each other
* they have been lumped together for lack of knowledge of evolutionary relationships that could sort them out
5
Q
By what means do protists move?
A
- Flagella/Cilia
- Pseudopodia (axopodia/filopodia)
- other means of propulsion
6
Q
Phototrophs
A
- rely on light for energy
* can and do make their own nutrients
7
Q
Heterotrophs
A
• Get their nutrients from another source
• Cannot make their nutrients
- osmotrophs ingest food in soluble form
- phagotrophs bring visible food particles into food vacuoles
8
Q
Mixotrophs
A
Both heterotrophic and phototrophic
9
Q
Protists means of reproduction
A
Asexual: Budding, mitosis, & schizogeny
Sexual: meiosis allows for genetic recombination
10
Q
Budding
A
A new organism develops from an outgrowth or bud due to cell division at one particular site
11
Q
Schizogony
A
Nucleus undergoes division preceding cell division - produces daughter cells called merozoites
12
Q
Genetic Recombination
A
Exchange of genetic material between different organisms which leads to production of offspring with a combination of traits that differs from those found in either parent
13
Q
What are the four supergroups of eukaryotes?
A
- Excavata
- Sar
- Archaeplastida
- Unikonta
14
Q
Excavata
A
- Diplomonads
- Basalids
- Euglenozoans
15
Q
SAR
A
- Diatoms
- Golden Algae
- Brown Algae
Chromalveolata • Dinoflagellates • Apicomplexans • Ciliates • Radiolarians • Forams • Cercozoans Oomycetes
- Stramenopila
- Alveolata
- Rhizaria
16
Q
Archaeplastida
A
- Red algae
- Chlorophytes
- Charophytes
- Plants
- Green Algae
17
Q
Unikonta
A
- Slime molds
- Tubulinids
- Entamoebas
- Gymnamoebas
- Nucleariids
- Fungi
- Choanoflagellates
- Animals
- Amoebozoans
- Opisthokonts
18
Q
Basic characteristics of diplomonads
A
- 2 nuclei
- unicellular
- move w/multiple flagella
- modified mitochondria called mitosomes
- Giadaria intestinalis causes diarrhea; parasite found in contaminated water & can pass from human to human
19
Q
Basic characteristics of parabasalids
A
- have undulating membranes
- move w/ flagella
- reduced mitochondria called hydrogenosomes
- Trichonympha species: lives in the gut of termites and digest cellulose
20
Q
Basic characteristics of euglenoids
A
- Free living eukaryotes
- Pocket at one end w/one or 2 flagella
- have mitochondria
- flexible pellicle can change shape
- 1/3 of euglenoids have chloroplasts & are fully autotrophic; may become heterotrophic in the dark
- others lack chloroplasts & are heterotrophic
- reproductive by mitosis
- no known sexual reproduction
- Euglena is photosynthetic
21
Q
Trichomonas vaginalis
A
STD in humans
- parabasalids
22
Q
Basic characteristics of kinetoplastids
A
- 2nd major group in Euglenozoa
- refers to unique, single mitochondria in each cell
- Evade immune response w/bait and switch defense; surface proteins are changed frequently
- Trypanosomes are disease-causing kinetoplastids
23
Q
African Sleeping sickness
A
- disease caused by kinetoplastids
* transmitted by tsetse fly
24
Q
Leishmaniasis
A
- Caused by kinetoplastids
* transmitted from sand flies
25
Chagas disease
* caused by kinetoplastids
| * transmitted by trypanosoma; small mammals carry the parasite
26
Basic characteristics of dinoflagellates
* photosynthetic unicells
* have two flagella located in grooves in the cellulose plate
* both marine & freshwater (majority in salt water)
* some are luminous
* “red tides” result from “blooms” of dinoflagellates - reproduction is crazy & can kill other animals/people if ingested
* “red tides” are detrimental to fishing industry
* they produce powerful toxin that inhibits diaphragm causing respiratory failure in vertebrates
* abundance of toxic dinoflagellates may result in death of marine mammals, fish, and birds which eat fish
* reproduce primarily by asexual reproduction (no sexual)
27
Basic characteristics of apicomplexans
* Spore-forming parasites of mammals
* have apical complex of organelles, vacuoles, fibrils, microtubules at one end of the cell
EX. Plasmodium causes malaria
- vector for plasmodium is the anopheles mosquito
28
Plasmodium Life Cycle - Step One
Mosquito bites person/animal & injects sporozoites into mammals system
29
Plasmodium Life Cycle - Step Two
The sporozoites travel to the liver via bloodstream
30
Plasmodium Life Cycle - Step Three
Sporozoites become merozoites and gametocytes
31
Plasmodium Life Cycle - Step Four
Liver cells burst (lyse) releasing more merozoites and gametocytes
32
Plasmodium Life Cycle - Step Five
Mosquito bites infected person picking up female & male gametocytes
33
Plasmodium Life Cycle - Step Six
Fertilization occurs in digestive tract of mosquito forming a zygote
34
Plasmodium Life Cycle - Step Seven
Zygotes undergo meiosis
35
Plasmodium Life Cycle - Step Eight
An oocyst releases a haploid sporozoites that migrate to the mosquitoes salivary glands
36
Basic characteristics of ciliates
* have large #’s 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
* has a pellicle
* Unicellular heterotrophs
* micro nucleus may only be needed for sexual reproduction
* Macro nucleus divided by mitosis & is involved w/physiological function
* vacuoles for ingesting food & maintaining water balance
* conjugation involves exchange of micro nuclei
37
Conjugation
Process by which one bacterium transfers genetic material to another through direct contact
38
Conjugation in Paramecia
* long way divided (looks like a mustache) - mitosis
* paramecium are parallel to each other & trade DNA
* 3 of 4 haploid cells disintegrate & 1 is kept - the one that stays goes through mitosis a second time
* once traded paramecia goes off
* 1 diploid micro nucleus
* this diploid goes through mitosis; making eight diploid cells - 4 macro nuclei & 4 micro
* divided until there are 4 paramecia each w 1 macro nuclei and 1 micro
39
4 types of stramenopila
* Brown algae
* Golden Algae
* Diatoms
* Oomycetes
40
Brown Algae
• most conspicuous seaweeds in northern regions (kelps)
• Thallus (the whole body) is a blade, stipe, and holdfast
• Algin: gel-forming substance used to thicken puddings, salad dressings, etc
• undergoes alterations of generations
- Sporophyte (spore planet diploid) goes through meiosis to produce spores
- Gametophyte (gamete plant) are smaller, filamentous individuals
41
Golden algae
* biflagellate
* freshwater or marine (plankton)
* All are photosynthetic; some mixotrophic
* Most unicellular; some colonial
* many species can form protective cysts if environmental conditions deteriorate
42
Diatoms
* unicellular; photosynthetic organisms
* phytoplankton
* double shells (looks like a box w/lid)
* made w/opaline silica
* live diatoms can withstand pressures as great as 1.4 mil kg/m^2 (equal to the pressure under each leg of a table supporting an elephant)
* Vibrating fibrils line grooves (raphes)
* Diatomaceous earth - filtering medium
43
Oomycetes
* water molds
* all are parasites or saprobes
* used to be categorized as fungi
* have motile spores (zoospores) w/2 unequal flagella
* sexual reproduction via male and female gametes
* zoospores reproduce asexually
* most live in water but terrestrial forms are plant pathogens
44
Phytophthora Infestans
* causes late blight of potatoes
| * Irish potato famine
45
Saprolegnia
* fish pathogen
| * can infect amphibians and kill amphibian eggs
46
Basic characteristics of radiolarians
* Glassy exoskeleton of silica
* bilateral or radial symmetry
* pseudopodia extend outward through small openings in the exoskeleton
* forms most of the ooze on sea floor
47
Basic characteristics of foraminiferans
* heterotrophic & marine protists
* many can derive nourishment from photosynthesis of symbiotic algae living within their tests
* fossils created limestone deposits (White cliffs of Dover)
* have tests (shells) of organic substances w/grains of calcium carbonate, sand, bits of echinoderm shells or, sponge spicules
* have podia (cytoplasmic projections) for gathering food and materials for their test and for swimming
48
Basic characteristics of cercozoans
* contains most of the amoeboid & flagellated protists that feed w/threadlike pseudopodia
* found in marine & freshwater; also in soil
* most are parasites or predators
49
Basic characteristics of red algae
* no centrioles, no flagella
* aka rhodophytes
* reproduce by alternation of generations
* produce pigments that give them a red color
* Porphyra is Japanese nori used to wrap sushi
50
Basic characteristics of green algae
• divided into two groups; charophytes & chlorophytes
• charophytes most related to land
• most chlorophytes have complex life cycles w/ both asexual and sexual reproduction
- biflagellated gametes w/cup-shaped chloroplasts
51
Unicellular chlorophytes
* 7000+ species mostly found in freshwater (some marine & terrestrial forms)
* chlamydomonas are simple, unicellular, resemble gametes or zoospores of more complex chlorophytes
* habitats include water (phytoplankton), damp, soil, inside eukaryotes (symbiosis), and snow
52
Colonial & multicellular chlorophytes
• Volvox is colonial as are filamentous forms of algae that form pond scum
• ulva forms true multicellular bodies by cell division and differentiation
- (sea lettuce) has developed alternation of generations
• Caulerpa shows repeated division of nuclei w/no cytoplasmic division so it is one big super cell
53
Amoeboids
* Plasmodial slime molds
* Cellular slime molds
* Tubulinids
* Entamoebas
54
Plasmodial Slime Molds
* multinucleate, moving mass of cytoplasm - feeding phase
* usually yellow or orange color
* feed on bacteria, yeast, & other organic material
* undergoes synchronous mitosis
* form sporangium under adverse conditions
55
Cellular Slime Molds
* individuals act like amoebas
* eat bacteria
* if food is scarce they aggregate to form a moving slug
56
Tubulinids
* used to be gymnamoebas
* large and varied group
* free living
* found in soil, freshwater, saltwater
* heterotrophs that feed on bacteria, other protists, & detritus
57
Entamoebas
• parasites of vertebrates & some invertebrates
• E. Histolytica causes amebic dysentery & is spread via contaminated food, water, or eating utensils
- May sometimes get to the brain and cause abscesses
58
Choanoflagellida
* most common ancestor of the sponges
* have single flagellum surrounded by collar of shorter filaments
* feed by straining bacteria from water w/their collar
